Lets talk water storage here

IF possible, I would say that by FAR the best bet would be to maybe store 10 gallon jugs or some such of bottled water for a short term thing (broken water main or some such) then put in a well with one of these http://www.deeprock.com/#Scene_2 or one of these http://www.hydratek2000.com/ and if cant do that then second choice might be to get 2 or 3 frac tanks and hook them up to the down spouts of te house. I know a lot of folks today wouldnt consider rain water stored for a long time in a tank to be drinkable water but it was for centuries and I use a tank we dump water into every couple weeks for our normal drinking water and we use water from barrels fairly often in the winter that has comonly been there for months with no special treatment and have had no problems.

 

Using a test kit is a great idea since most folks probably get their water from a water purveyor. Being the water is already chlorinated, you wouldn't want to add to much. I never took this into consideration and not sure why.

Thanks

 

Even if you over do it, it is not a big deal. If you have to much chlorine, leave it out and aerate it and it will off gas the chlorine fairly soon. The taste will turn you off way before the chlorine level will burn you. Ever been to a over chlorinated swimming pool?

 

Following you will find information on the difference and limitations of booster/shallow well and deep well jet pumps and other types of pumps and methods for lifting water.

 

What is a jet pump and how does it differ from a centrifugal pump?

<table width="100%"> <tbody><tr> <td> <table align="left" width="150"> <tbody><tr> <td> <table cellpadding="0" cellspacing="0"> <tbody><tr> <td></td> </tr> <tr> <td>Figure 1.</td> </tr> </tbody></table>


</td> </tr> </tbody></table> </td> </tr> </tbody></table>A jet pump actually is two pumps in one: a centrifugal pump and a jet assembly, commonly called an injector. Figure 1 shows a typical shallow well jet pump. Parts 1, 2, and 3, the adapter, nozzle and venturi on the left side of the pump are the injector or jet components. We refer to the entire package – the centrifugal pump and injector – as the jet pump. The centrifugal pump part of a jet pump package is specifically designed to operate in conjunction with an injector, and the injector enhances a centrifugal pumps pressure capability by about 50 percent. Shallow well jets have the injector attached to the pump above ground level and are limited to about 25 feet of lift, just like straight centrifugal pumps. Their only advantage over a straight centrifugal is their pressure boosting capability.

Deep well jets, on the other hand, have their jet injector down in the well below the water level, so they push the water to the surface. See Figure 2. Deep well jet pumps are not limited by atmospheric pressure to 25 feet of lift. A good deep well jet can pump water from as deep as 200 feet. Remember, when we say we are pumping from 200 feet, we are referring to the distance from the surface of the water in the well to the discharge point at or above ground level, not from the injector to the discharge point.
If the jet pump is so designed that the injector can be either attached directly to the pump or located down in the well, it is known as a convertible jet pump. Convertible jet pumps therefore can be operated as either a shallow well jet or a deep well jet. With that background, we now will look at the jet assembly to see how it functions.


<table width="100%"> <tbody><tr> <td> <table align="left" width="150"> <tbody><tr> <td> <table cellpadding="0" cellspacing="0"> <tbody><tr> <td></td> </tr> <tr> <td>Figure 2.</td> </tr> </tbody></table>


</td> </tr> </tbody></table> </td> </tr> </tbody></table>The jet assembly or injector consists of three major parts — the jet body, the nozzle and the venturi. Here is how it works: With the centrifugal pump primed and pumping, a portion of the water leaving the impeller is diverted back to the injector. The amount of water diverted is determined by the pump design in a shallow well jet and is not adjustable. In deep well jets and convertible jets, it is adjustable by means of a control valve, which is the subject of next month’s article. Figure 3 shows a deep well injector. This diverted portion that powers the injector, called drive water, is directed through the nozzle where it accelerates just like water passing through the nozzle at the end of a garden hose. The drive water stream is directed through a gap toward the venturi, creating a partial vacuum at the gap. Here, atmospheric pressure forces product water (well water) to enter the injector and mix with drive water as it enters the venturi. The outward flair of the venturi reduces the velocity of the stream as it passes through, converting it back into pressure and directing it into the eye of the impeller where it is further pressurized. Upon leaving the impeller, a portion exits the pump to become service water, and the rest is returned to the injector as drive water.



<table width="100%"> <tbody><tr> <td> <table align="left" width="150"> <tbody><tr> <td> <table cellpadding="0" cellspacing="0"> <tbody><tr> <td></td> </tr> <tr> <td>Figure 3.</td> </tr> </tbody></table>


</td> </tr> </tbody></table> </td> </tr> </tbody></table>In a shallow well application, a single pipe is connected to the inlet of the injector and extended down into the well. In a deep well application, the injector is down in the well, requiring two water passages from the pump into the well, one for feed water and the other for product water. As you’ll see in the following paragraph, one of the passages can be the well casing. For right now, we will refer to both passages as pipes. The feed water pipe is often called the pressure pipe, and product water pipe is often referred to as the suction pipe, which is a bit of a misnomer since it too is under pressure. I prefer to call the product water pipe the discharge pipe, and it should be one size larger than the feed pipe since it carries more water. Deep well systems are broken down into two sub-types, double-pipe and single-pipe. When the well casing is four inches or larger in diameter, a double-pipe system normally is preferred. Where the well casing is smaller than four inches in diameter, a single-pipe deep well injector can be used. It differs from a standard two-pipe deep well injector in that it is smaller in diameter, is hung from a single suction pipe and includes packers that seal against the casing. A well casing adapter seals the top of the casing and provides a means of introducing feed water into the casing. With both ends sealed, the well casing acts as the second pipe for the drive water. Obviously, for a single pipe injector to work properly, the casing must be in good shape.

To keep jet pumps primed, it is important to install a foot valve at the bottom of the suction pipe to prevent the water in the system from draining back into the well when the pump is off. This applies to all types of jet pumps.

A question that often comes up: Will a jet pump work without the jet? The answer is yes, but… Yes, because it will pump water, but no, because it may destroy itself by pumping too much water. One of the advantages of a jet pump is that it cannot be overloaded on the horsepower curve because we create artificial head with the pressure regulator and nozzle. Without the jet assembly, a jet pump can pump beyond its curve, draw too much power, overheat the motor and possibly burn it up.

Bottom line: Don’t use a jet pump without the injector.

 

Single Line Jet Pumps & Water Wells, Explanation & Repairs
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• Single Line Jet Pumps & Water Wells, Explanation & Repair Advice
• What are the components of a one line jet pump water supply system?
• What types of wells use a one-line jet pump for water delivery?
• Types of wells and water supply systems and what to watch out for with each
• Well pump & water tank diagnosis & repair procedures

[SIZE=-2]Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.[/SIZE] <ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="aswift_3_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins>
<ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="aswift_4_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins> This article describes the components of a one-line jet pump water system, what the components look like, and what they do.This article also describes Single Line Jet Pumps & Water Wells, Explanation & Repair Advice. We provide advice about what to do when things go wrong.
Readers of this document should also see our other diagnostic guides for water pumps, wells, motors, in table form:

• [SIZE=-1]ELECTRIC MOTOR DIAGNOSTIC GUIDE[/SIZE] - table format and text.
• [SIZE=-1]SHORT CYCLING DIAGNOSIS TABLE[/SIZE] - table format. Also see [SIZE=-1]SHORT CYCLING WATER PUMP[/SIZE] - text.
• [SIZE=-1]WATER PRESSURE PROBLEM DIAGNOSIS TABLE[/SIZE] - table format. Also see [SIZE=-1]WATER PRESSURE LOSS DIAGNOSIS & REPAIR[/SIZE] - text.
• [SIZE=-1]WATER PUMP PROBLEM DIAGNOSTIC TABLE[/SIZE] - table format. Also see [SIZE=-1]WATER PUMP PROBLEM DIAGNOSTIC TABLE[/SIZE] - text

Readers of this document should also see [SIZE=-1]WATER PUMP, ONE LINE JET OPERATION[/SIZE], and see Water Tank Types and before assuming that a water problem is due to the well itself, see Water pump and pressure tank repair diagnosis & cost which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost. If your building has water pressure problems, see [SIZE=-1]WELL WATER PRESSURE DIAGNOSIS[/SIZE]. Readers whose wells simply run out of water should also see How to Test Well Water Quantity and see How to Get More Water From a Well. If your well pump won't start see [SIZE=-1]ELECTRIC MOTOR OVERLOAD RESET SWITCH[/SIZE] for some electric motor or pump motor troubleshooting suggestions.

© Copyright 2010 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.
What are the Components of a Shallow Well with a One Line Jet Pump?

<table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%"> By definition, if a one-line jet pump is installed at a building, the well is a "shallow well", possibly a bored well or a hand dug well, or even a shallow drilled well. Here Carson Dunlop's sketch shows the difference between a 'deep well' and a 'shallow well'.
Refer also to our sketch just below where we depict a shallow well (less than 20 feet deep) served by a one-line jet pump located apart from the well.
A shallow well might be capable of delivering plenty of water, depending on just where it is located, but there are water quality concerns with shallow wells.
A shallow water well is more likely to receive surface runoff, making it a bit more at risk of contamination by bacteria or any chemical that might be on local ground surfaces such as road salt, fertilizers, or pesticides.
Most "shallow water wells" are less than 30 feet deep (so the foot valve is at 24-feet depth or less) and use an above-ground single-line jet pump to "suck" or draw water up from the well. These pumps cannot pull water from much deeper. Water from deeper wells is delivered by a 2-line jet pump (also above ground) or a submersible in-well pump. More about measuring the actual depth of a well is at [SIZE=-1]DEPTH of a WELL, HOW TO MEASURE[/SIZE].
</td></tr></tbody></table> An Explanation of the Parts of a Shallow Water Well

<table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%">
</td></tr></tbody></table> The following list and definition of water well parts and terms is organized from the top of our rough drawing towards its bottom and uses names that correspond to those shown in our ugly drawing. The nicer drawing of a one line jet pump is provided courtesy of Carson Dunlop and provides additional details about single line shallow well jet pump water systems. First we describe items listed on the right side of our sketch, second we describe items and terms listed on the left side of the sketch.
Buried well casing which is typical for older shallow wells - the well casing top may be above ground, buried and hidden from view entirely, or (luckily) located inside of a well pit (less common). It is particularly important that the well cap on the casing be water tight since otherwise unsanitary surface water and debris can enter the well casing.

Many well caps are not water tight, which is why modern drilled well casings extend above ground level. A one line jet pump might also be installed to draw water from other shallow water supply sources including a hand dug well (discussed at Hand Dug Wells) a cistern (discussed at [SIZE=-1]CISTERNS[/SIZE]), or a spring which includes a water collection pit (discussed at Springs as a Water Supply).
What is a One Line Jet Pump?

<table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%">

• A "one-line" jet pump is shown outside of the well, either inside of the building such as the blue water pump in our page top photo or like this green one line jet pump or perhaps in a well pit or well house. "One line" refers to the fact that a single pipe connects the pump intake to the well, and the pump has to lift water out of the well and into the building it serves. If your well pump won't start see [SIZE=-1]ELECTRIC MOTOR OVERLOAD RESET SWITCH[/SIZE] for some electric motor or pump motor troubleshooting suggestions.
  
  Since the lift capacity of a one-line jet pump is limited to about 27' (usually 25 feet or less) you can bet that where you find this type of pump installed it is drawing from a shallow water well.
  
  Our sketch shows the water pump connected to a water pressure tank which in turn supplies water to the building. The pressure tank is usually located very close to the jet pump but it could be elsewhere.
• Pitless Adapter is the special fitting that seals the hole in the well casing where the water piping makes its right angled turn and then exits the well casing to pass on to the building.
• Water piping to the house rises vertically inside the well casing from the top of the foot valve (see below) to a point (below the frost line in cold climates) where it makes a right angled turn and passes out through the well casing and onwards to the water pump and pressure tank.
• Well casing is in this sketch the 6-inch diameter steel pipe which is driven into the well from above ground into bedrock, then sealed against groundwater leaks.
• Foot Valve is a one way or anti-siphon valve which is installed on the pick-up end of the water pipe near the bottom of the well. The foot valve prevents water from flowing backwards out of the jet pump and well piping back into the well when the jet pump stops operating. See [SIZE=-1]WELL PIPING FOOT VALVES[/SIZE] for details about this component. You can see Carson Dunlop's sketch of a foot valve here.
  
  If the foot valve is leaky and water runs back into the well we increase the wear on the water pump as it has to run more often, and pretty soon the water pump will lose its prime (water inside the pump mechanism) and it may be unable to retrieve any more water from the well whatsoever.
  
  When a shallow well appears to have "run dry" one of the first things to check is whether or not the foot valve needs to be replaced.
• Foot Valve Clearance from Bottom shows that the well piping and foot valve are inserted into the well some distance from the very bottom of the well (inches to a few feet). We need this clearance to reduce the tendency of the well pump to pick up mud and debris from the bottom of the well.
• Static head shown in this sketch is the height of the column of water inside of the well between the bottom of the foot valve and the top of the water when the well is at rest. We discuss "static head" and well recovery rates in detail at How Much Water is In the Well? More about measuring the actual depth of a well is at [SIZE=-1]DEPTH of a WELL, HOW TO MEASURE[/SIZE].
• See [SIZE=-1]WATER PUMP, ONE LINE JET OPERATION[/SIZE] for a description of the operating sequence and controls on a one line jet pump water system.

</td></tr></tbody></table> What is the Pumping Capacity in Gallons per Minute for a 1-Line Shallow Well Jet Pump?

A one-line jet pump can typically raise water from depths of just a few feet (or "0" depth) to about 25 feet in depth, and at water delivery rates of 4 gpm up to as much as 25 gpm depending on the variables we list below the well pump capacity tables shown. At [SIZE=-1]WATER PUMP CAPACITIES TYPES RATES GPM[/SIZE] we compare the pumping capacities of one line jet pumps, two line jet pumps, submersible well pumps, and other water pumping methods.
A nice example table of shallow well 1-Line Jet Pump Capacities for 1/2 hp, 3/4, and 1 hp shallow well pumps is provided in the Water Ace Jet Pump Installation Manual and excerpted below to illustrate the factors that determine well pump capacity. Both of the charts below are for one-line jet pumps produced by Water Ace. 1-Line jet pumps intended for shallow well use and made by other manufacturers can be expected to have similar capacities.
<table cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td valign="TOP" width="70%"> </td> </tr> </tbody></table> The Water Ace charts (shown in part above) make clear that the capacity of a one-line shallow well jet pump to deliver water at a given flow rate varies by these factors:

1. the depth of the well (the bottom scale in the two charts)
2. the pump horsepower (the color codes indicate pump model and horsepower HP variation)
3. The well pump model (the right hand table is for the company's more powerful well pump series of 2-line jet pumps)
4. The condition of well piping, including pipe diameter, length, number of bends or elbows
5. The presumption that the entire piping system has no leaks

Permission requested, Water Ace Corp. Aug 2010 - Pentair Pump Group.
Watch out: Safety warnings are throughout any pump manufacturer's instructions. Because some pump models are capable of developing internal pressures of more than 100 psi, if your building piping, pressure relief valves, safety controls, wiring, and plumbing are not properly installed, very dangerous conditions including electrical shock, tank explosion, and leaks or floods can occur.

 

How Does a One Line Jet Pump Well Water Pump Work?
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• Sequence of operation of a well and pump system using a one line jet pump
• Installation and troubleshooting for one line jet pumps used for private well water supply

[SIZE=-2]Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.[/SIZE] <ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="google_ads_frame4_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins>
<ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="google_ads_frame5_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins> This article describes the sequence of operating steps in a one-line jet pump water system. The process of diagnosis and the costs of the repair are explained. Consumer advice on saving money on water supply repair costs includes a review of the parts and labor costs of a typical well pump and pressure tank replacement case. Carson Dunlop's sketch (at page top) shows the main parts of a one-line jet pump well installation. Readers of this document should also see our other diagnostic guides for water pumps, wells, motors, in table form:

• [SIZE=-1]ELECTRIC MOTOR DIAGNOSTIC GUIDE[/SIZE] - table format and text.
• [SIZE=-1]SHORT CYCLING DIAGNOSIS TABLE[/SIZE] - table format. Also see [SIZE=-1]SHORT CYCLING WATER PUMP[/SIZE] - text.
• [SIZE=-1]WATER PRESSURE PROBLEM DIAGNOSIS TABLE[/SIZE] - table format. Also see [SIZE=-1]WATER PRESSURE LOSS DIAGNOSIS & REPAIR[/SIZE] - text.
• [SIZE=-1]WATER PUMP PROBLEM DIAGNOSTIC TABLE[/SIZE] - table format. Also see [SIZE=-1]WATER PUMP PROBLEM DIAGNOSTIC TABLE[/SIZE] - text

See [SIZE=-1]WATER PUMP, ONE LINE JET[/SIZE] for a description of the function of each component of a one-line jet pump system. Readers should also see [SIZE=-1]IDENTIFY WELL PUMP TANK COMPONENTS[/SIZE]. Nearly all well pumping systems, one line jet pump, two line jet pump, or submersible well pump, require a foot valve installed at the bottom of the well piping. If your building has water pressure problems, see [SIZE=-1]WELL WATER PRESSURE DIAGNOSIS[/SIZE]. Readers whose wells simply run out of water should also see How to Test Well Water Quantity and see How to Get More Water From a Well.
© Copyright 2010 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.
How a One-Line Jet Pump Well Water System Works - Sequence of Operating Steps

What happens when you turn on the water at a faucet in a building whose water is supplied by a one-line jet pump? (See the sketch at the top of this page for the basic components of a one-line jet pump system.) Our photograph (left) shows a one-line jet pump installed in a home.
Notice that there is a horizontal pipe with a check valve? That's the pipe leading to the water source. (We explain this check valve at [SIZE=-1]WELL PIPING CHECK VALVES[/SIZE].)
The vertical pipe rising from the pump is the jet pump outlet connection that sends pressurized water to the water pressure tank and onwards to the rest of the building.
The following steps describe normal operating of a building well pump and water supply system. Other cases in which the well pump controls are not working properly, there is a problem with the controls, pressure tank, pump, or well itself are discussed at [SIZE=-1]WATER PRESSURE REPAIR GUIDE & COSTS[/SIZE] and at [SIZE=-1]WELL WATER PRESSURE DIAGNOSIS[/SIZE].

1. Turn on building water at a plumbing fixture: open a sink valve, tub valve, or flush a toilet.
2. Water runs out of the supply faucet, into the fixture, down the drain
3. Water pressure and flow are being supplied to the building from a water pressure tank. If we didn't use a pressure tank, because water is not very compressible, the second water was turned on, water pressure in the system would drop below the pump cut-on pressure, the pump would turn on, and probably bring water pressure up to the cut-off pressure quickly, causing short cycling and burning up pump controls or a pump motor. See [SIZE=-1]WATER TANKS HOW THEY WORK[/SIZE].
4. Pressure in the water pressure tank and in the building piping system drops down to the well pump cut-in pressure. Typically this is 20 or 30 psi on a residential water system.
5. The well pump pressure control switch senses the pressure drop, closes an internal electrical relay switch to turn on the well pump. See [SIZE=-1]WATER PUMP PRESSURE CONTROL[/SIZE].
6. The well pump motor runs, drawing water back into the building from the well by "sucking" water up from a shallow depth (a one-line jet pump can't draw water from much below 25 feet)
7. Water is forced into the building water pressure tank and simultaneously into the building piping and on to the plumbing fixtures.
8. If the pump sends water into the building faster than water is flowing out of the open faucet or plumbing fixture, the pump will "get ahead" of the water flow, successfully pressurizing the water tank, causing the pressure switch to turn off the pump (see step 10 below).
   
   OR
9. If the pump cannot send water into the building faster than water is flowing out of the open faucet or plumbing fixture, the well pump will run continuously and water will flow out of the open faucet or plumbing fixture at a rate limited basically by the pump's water delivery flow rate in gallons per minute. You'll also find this condition if a building water supply pipe bursts. We say "basically" because the well piping and building piping and faucets themselves offer some back-pressure against the pump's flow rate. In this case, the well pump will continue to run until the building faucets or plumbing fixtures are turned off. At that point ...
10. The well pump pressure control switch senses that water pressure has increased to the cut-out point, opening its switch and turning off electrical power to the well pump. The well pump has re-pressurized the building water tank and piping up to the cut-out or cut-off water pressure.
11. The foot valve closes (at the bottom of the well piping) and/or a check valve located in the building on or close to the well pump closes, preventing water and pressure from flowing backwards down into the well, losing building water pressure and possibly losing pump prime. See [SIZE=-1]WELL PIPING FOOT VALVES[/SIZE] and see [SIZE=-1]WELL PIPING CHECK VALVES[/SIZE] and if necessary, [SIZE=-1]WELL PUMP PRIMING PROCEDURE[/SIZE].

How to Diagnose Poor Well Water or Pump Water Pressure

For our complete water pressure and pump, well, and piping problems diagnostic article list, see [SIZE=-1]WATER PRESSURE REPAIR GUIDE & COSTS[/SIZE] and [SIZE=-1]WATER PRESSURE LOSS DIAGNOSIS & REPAIR[/SIZE]. Separately we also provide a [SIZE=-1]WATER PRESSURE PROBLEM DIAGNOSIS TABLE[/SIZE]. The following articles pertain if you have a private well, pump, and tank system for your building or if your incoming community water supply pressure and flow are just too low to start with:

1. Water Tank Problems? See Water Pressure Tank Problems. Examples of water tank problems include poor water pressure or the well pump rapidly turning on and off (short cycling).
2. Water pump problems? Examples of water pump problems include poor water pressure or no water pressure at all. See
   • [SIZE=-1]WATER PUMP PRESSURE CONTROL ADJUSTMENT[/SIZE] - poor building water pressure or flow
   • [SIZE=-1]PUMP PRESSURE CONTROL REPAIR[/SIZE] - pump is not delivering water at all or water pressure is poor
   • [SIZE=-1]WATER PUMP RELAY SWITCH[/SIZE] - submersible pump has stopped working
   • [SIZE=-1]WATER PUMP PRIMING PROCEDURE[/SIZE] - well pump keeps losing prime - pump runs but gives no water
   • [SIZE=-1]WATER PUMPS & TANKS & WELLS[/SIZE] - complete list of articles
   • [SIZE=-1]WATER PUMP CONTROLS & SWITCHES[/SIZE] - complete list of well pump controls and switches, identification, diagnosis, repair
   • [SIZE=-1]WATER PRESSURE GAUGE ACCURACY[/SIZE] - maybe water pressure is fine and it's the gauge that's bad?
3. Water piping or well piping problems? If your water pump keeps losing prime, a shallow well jet pump well line could have a bad foot valve (in the well [SIZE=-1]WELL PIPING FOOT VALVES[/SIZE]) or there may be a bad check valve on well piping at or near the water tank or near the above-ground water pump ([SIZE=-1]CHECK VALVES[/SIZE]) and so be losing prime. A leak in the well line piping itself can also lead to loss of prime.
4. Well Problems? Do you run out of water or after running water for some interval water pressure and flow are poor? Well problem diagnosis starts at [SIZE=-1] WELLS CISTERNS & SPRINGS[/SIZE]. Before assuming that there is no water in the well, check to see if the water pump is working properly, including loss of pump prime ([SIZE=-1]WATER PUMP PRIMING PROCEDURE[/SIZE]) and a bad or leaky well piping foot valve ([SIZE=-1]WELL PIPING FOOT VALVES[/SIZE]).
5. Bad water pump or water tank pressure regulator control? See WATER PRESSURE REDUCER / REGULATOR (not usually installed on private well and pump systems, often present on municipal water supply systems that use an in-building local water pump and pressure tank to boost pressure). Water pump pressure regulator switch diagnosis and repair steps include these:
   • How to Adjust Water Pump Pressure: The detailed, step by step procedure for inspecting and adjusting the water pressure control switch is discussed in detail at [SIZE=-1]ADJUST PUMP PRESSURE CONTROL[/SIZE].
   • Diagnosing Water Pump Short Cycling on and off: If your water pump is clicking on and off too often or quite rapidly see [SIZE=-1]SHORT CYCLING[/SIZE].
   • Diagnosing Water Pressure Drops without explanation when the pump stops, see Water Pressure Falls Slowly, Erratic Pumping: bad pressure control switch, building water running or leak, bad pressure gauge, bad check valve, bad foot valve.
   • Diagnosing & Repairing Lost Air in the Water Tank: The problem of lost air in the water pressure tank along with how to correct that condition are discussed beginning at [SIZE=-1]SIGNS OF AIR LOSS[/SIZE].
   • Diagnosing & Repairing a Water Pressure Control or Water Pump Control Switch: We discuss diagnosing and repairing a water pressure control switch that sticks "on" or "off" or simply won't operate, at water pump Pressure Switch Repairs.
6. Bad Hot Water Pressure? See [SIZE=-1]HOT WATER IMPROVEMENT[/SIZE] especially if the building cold water pressure is acceptable but hot water pressure and flow are poor. Accumulated debris in a water heater, and debris from a corroded or disintegrating hot water tank dip tube or hot water tank sacrificial anode can also block the hot water outlet opening, resulting in low hot water pressure in a building.
7. Bad cold or hot water pressure and flow just at certain plumbing fixtures? See our discussion of Poor water pressure just at certain plumbing fixtures just above.
8. Problems with water treatment equipment can cause loss of water pressure or no water flow: a clogged water filter, or a malfunction in water disinfection or other water treatment equipment can cause a reduction in water pressure or even a complete stop in water flow in a building. See [SIZE=-1]WATER FILTERS[/SIZE] for details about clogged filters, and see [SIZE=-1]WATER TREATMENT EQUIPMENT CHOICES[/SIZE] for our complete list of types of water treatment equipment.

 

Water Pressure Booster Pump & Tank Systems
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• Guide to Pumps & Pressure Tanks Used to Boost Water Pressure in Buildings
• Adding a water pressure boost pump to private, community,or municipal water supply
• Adding a water pressure boosting pump to private well, cistern, or spring systems
• How to add a booster pump to improve water pressure on upper building floors
• Connecting water pumps and pressure tanks in series - details.

[SIZE=-2]Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.[/SIZE] <ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="aswift_3_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins>
<ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="aswift_4_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins> This article describes the use of water pressure boosting systems that add a pump and pressure tank to improve water pressure and flow. Readers of this document should see [SIZE=-1]WATER PRESSURE LOSS DIAGNOSIS & REPAIR[/SIZE] before assuming that a water pressure problem is due to the community supply system pressure or private well itself. Water pump and pressure tank repair diagnosis & cost describes a specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost.
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When and Why are Water Pressure Booster Systems Needed

Poor city water pressure: Some community water supplies may provide only modest incoming water pressure, perhaps at 30 psi or even less. Some examples of low water pressure supply sources even where community or municipal water supply is provided are listed here.
Effect of building height on water pressure: The Home Reference Book points out that Gravity is another source of pres- sure loss. Energy is required to push the water uphill. For every one foot we push water up, we lose 0.434 psi. Another way of saying this is that it takes one psi to move water up 2.31 feet.
A plumbing system will typically lose eight psi of water pressure in a two-story house, getting the water from the basement up to the second floor bathroom. With no water flowing, the static pressure at the street main may be 60 psi, but the static pressure at the second floor basin might be 51 psi. Houses that are above the street or have third story plumbing fixtures, have a pressure disadvantage.
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• Homes at the end of a water supply line: Community water supply systems serving just a few or even many homes, but with some homes near the end of the system
• Buildings located high above a water supply line: or located far uphill from the pumping station receiving only modest incoming water pressure, perhaps less than 30 psi.
• Tall residential properties requiring additional water pressure to serve upper floors. For a tall home connected to a community water supply providing incoming water at only 30 psi, for example, the top floor may see 17 psi unless a booster pump and pressure tank are installed. (Very tall buildings such as skyscrapers and offices and multi-story apartment buildings are more likely to install a rooftop water supply tank which is fed by a pump from street level but which in turn provides water down through the building by gravity.) Sketch, courtesy of Carson Dunlop
• Gravity water systems: Community water supply systems serving many homes but supplying water only during certain hours of the day, or only at very low pressure. For example San Miguel de Allende, Mexico, with a population of about 100,000 people, is served by nine water wells and pumping stations. But water is delivered to most homes by gravity, and in some seasons, only at certain hours of the day. A photo of a rooftop water storage system of this type can be seen at Rooftop Water Systems.

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• Problems with the water water service pipe connecting the home to city water mains: Even if a municipal water system gives good pressure and quantity, as the Home Reference Book points out, the city's own water shutoff valve outside but near the property line may also restrict flow or the supply line from the street to the house may be undersized, damaged or leaking. Long runs of relatively small (1/2-inch diameter) pipe result in considerable pressure drop, especially with more than one fixture flowing. Solutions include replacement with larger pipe or shortening the runs, but in some cases homeowners may try adding a local booster pump instead.
• Adding plumbing fixtures (a new bathroom, for example) without enlarging or adding pipes often leads to pressure complaints. A crimped, damaged or clogged pipe within the house will adversely affect pressure. This is common with amateurish work. On a private system, a defective, undersized or poorly adjusted pump will result in poor pressure. Individual faucets may also be defective.

Homes on gravity water systems such as we describe in the San Miguel de Allende case usually install a rooftop water tank or cistern to which water is replenished periodically. The rooftop water cistern provides water to the local building whenever it is needed.
But some homes in such a community may because of their location or construction or because they have no high spot to place their water tank, have only very low water pressure.
What are the Components of a Water Pressure Boosting System

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Our sketch, courtesy of Carson Dunlop and edited by the author shows a simple one line jet-pump and pressure tank connected to the incoming water line in a building. Our photo at page top shows a typical water pressure booster pump and tank system for sale at Don Pedro's Ferreteria in San Miguel de Allende.
The incoming community water supply line which normally is fed through a pressure regulator and into building supply piping is first connected to a water pump, usually a 1-line jet pump. The pressure regulator control is not shown in this sketch.
The water pump is in turn connected to a pressure tank, possibly a large one to give a good high pressure water supply to the building.
As water is drawn into the home (someone turns on a faucet) the pressure tank feeds pump-boosted water pressure to the building, and as water pressure drops in the water tank, the jet pump draws more water from the community supply line, boosting its pressure into the pressure tank.
Typically the booster pump pressure control switch will be set to operate in the 30-50 psi range, providing good water pressure to the building.
In a private well water supply system this pump and tank combination may be connected directly to the well, that is, the incoming water line shown in the left of the sketch is connected to a foot valve immersed in the water well. at [SIZE=-1]WATER PUMP, ONE LINE JET[/SIZE] we discuss one-line jet pumps in more detail. at [SIZE=-1]WATER PUMP CONTROLS & SWITCHES[/SIZE] we discuss the pump pressure control switch and how it can be adjusted to provide higher water pressure.
</td></tr></tbody></table> <table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%"> What kind of water pressure booster pump do we need?

The reason that a typical residential property needs just a one-line jet pump to provide its water pressure boost is that there is already water arriving at the building under some pressure - the pump does not have to combine lift of the water from deep in the ground to high in the building.
Our photo of a pressure booster pump and tank system at left (and at page top) shows that stainless steel parts were used to enclose the pump parts: this system is designed for outdoor use in a non-freezing climate. You can see the pressure gauge and the gray box housing the pump pressure control switches above the stainless-steel covered pump assembly itself.
</td></tr></tbody></table> <table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%"> Do we need a more powerful water pump or larger diameter water supply piping?

Some water pressure booster applications may require a more powerful pump than the type we discuss here, particularly if the anticipated water flow or usage rate in the building is high.
Carson Dunlop's chart at left explains that in an individual plumbing system (that is, changing nothing but water flow rate), the water pressure observed at a fixture (and in the piping) will drop off significantly as the water flow rate increases.
This chart explains why the water pressure in your shower may fall off substantially during your bathing if someone else in the building flushes a toilet or turns on the dishwasher.
The chart also demonstrates that using larger diameter piping for the water supply in a building can significantly reduce the pressure drop when multiple fixtures are running at the same time.
</td></tr></tbody></table> Using a Booster Pump to Improve Water Pressure on the Upper Floor of a Building

When incoming water pressure at a building is low, a water pressure "booster pump" may be installed on upper building floors or on a building roof to provide improved water pressure for the occupants of upper building floors.
If the incoming water pressure is from a municipal system and the building is just two or three floors high, the booster pump might be on ground level, as we described at the start of this article.
But if the incoming water pressure at a building is being provided by a well pump and water pressure tank system, and if the building is taller than three floors, the existing well pump may not be capable of delivering adequate water pressure nor adequate water floor to occupants of a fourth or higher floor.
Installing a Booster Pump for Water Pressure on the Fourth Floor of a Residential Building

Beginning on the 4th floor of such a building, install an additional pressure tank next to the second pump.
The ground floor pump will send water into the incoming pipe connection of your 4th floor pump itself.
We are assuming that your 4th floor pump will be a 1-line jet pump - that is, a single pipe connects to the pump inlet port and a single pipe connects from the pump outlet to the inlet connection of a pressure tank.
Fourth floor cold water piping should be fed by the outlet connection on the pressure tank. [SIZE=-1]WATER PUMP, ONE LINE JET[/SIZE] shows what a common 1-line jet pump looks like, and [SIZE=-1]WATER PUMP, ONE LINE JET OPERATION[/SIZE] explains how one line jet pumps work.
In our one line jet pump photo (left) the black plastic pipe coming up from lower left is attached to the pump's inlet port where an internal check valve prevents water from siphoning back out of the pump and tank into the well when the pump shuts down.
At the top right of this pump you can just make out the water connection leaving the pump where it heads up into a copper pipe.
The 4th floor pump will turn "on" when the pressure switch connected to its 4th floor pressure tank senses pressure dropping below the cut-in point, and it will cut "off" when the 4th floor pump has boosted pressure in your 4th floor tank up to the cutout pressure.
We expect that given that the 4th floor pump will have always at least some incoming water pressure, though low, it should be able to add additional lift t boost the 4th floor pressure as you want.
The "lift" capacity of a water pump that is a one-line jet pump is a little under 10 meters - but that's without any incoming pressure to the pump from the one located on the 1st floor.

 

3.7 RECIPROCATING INERTIA (JOGGLE) PUMPS

This range of pumps depend on accelerating a mass of water and then releasing it; in other words, on "throwing" water. They are sometimes known as "inertia" pumps.
As with the other families of pumps so far reviewed, there are both reciprocating inertia pumps, described below, (which are only rarely used) and much more common rotary types which include the centrifugal pump, described in Section 3.8.

3.7.1 Flap Valve Pump

This is an extremely simple type of pump which can readily be improvized; (see Fig. 54). Versions have been made from materials such as bamboo and the dimensions are not critical, so that little precision is needed in building it.

The entire pump and riser pipe are joggled up and down by a hand lever, so that on the up-stroke the flap valve is sucked closed and a column of water is drawn up the pipe, so that when the direction of motion is suddenly reversed the column of water travels with sufficient momentum to push open the flap valve and discharge from the outlet. Clearly a pump of this kind depends on atmospheric pressure to raise the water, so it is limited to pumping lifts of no more than 5-6m.

3.7.2 Resonant Joggle Pump

Fig. 55 shows an improved version of the flap-valve pump. Here there is an air space at the top of the pump which interacts with the column of water by acting as a spring, to absorb energy and then use it to expel water for a greater part of the stroke than is possible with a simple flap-valve pump.

This uses exactly the same principle as for an air chamber (see Section 3.5.4).

Fig. 54 Flap valve pump​

Fig. 55 Joggle pump​

The joggle pump depends on being worked at the correct speed to make it resonate.

An example of a resonant device is a weight hanging from a spring, which will bounce up and down with a natural frequency determined by the stiffness of the spring and the magnitude of the weight. The heavier the weight in relation to the spring stiffness, the slower the natural frequency and vice-versa. If the spring is tweaked regularly, with a frequency close to its natural frequency, then a small regular pull applied once per bounce can produce a large movement quite easily, which is an example of resonance.

In exactly the same way, each stroke of a resonant joggle pump makes a column of water of a certain mass bounce on the cushion of air at the top of the column. Depending on the size of the air chamber and the mass of the water, this combination will tend to bounce at a certain resonant frequency.

Once it has been started, a pump of this kind needs just a regular "tweak" of the handle at the right frequency to keep the water bouncing. This effect not only improves the overall efficiency but makes it relatively effortless to use. Dunn [20] reports performance figures of 60 to 100 litres/minute lifted through 1.5 to 6m at a frequency of 80 strokes per minute.

It is worth noting that the performance of some reciprocating piston pumps fitted with airchambers (as in Fig. 36 C) can be similarly enhanced if the speed of the pump is adjusted to match the resonant frequency of the water in the pipeline and the "stiffness" of the trapped air in the air-chamber.

This is usually only feasible with short pipelines at fairly low heads, as otherwise the natural frequency in most practical cases is far too low to match any reasonable pump speed.

If resonance is achieved in such situations the pump will often achieve volumetric efficiencies in the region of 150 to 200%; i.e. approaching twice the swept volume of the pump can be delivered. This is because the water continues to travel by inertial effects even when the pump piston is moving against the direction of flow, (the valves of course must remain open). As a result, water gets delivered for part of the down stroke as well as on the up stroke.

Well-engineered reciprocating systems taking advantage of resonance can achieve high speeds and high efficiencies. Conversely, care may be needed in some situations (such as pumps where there is a reversal of the direction of flow), to avoid resonance effects, as although they can improve the output, they can also impose excessive loads on the pump or on its drive mechanism.

 

3.8 ROTODYNAMIC PUMPS

3.8.1 Rotodynamic Pumps: Basic Principles

The whole family of so-called rotodynamic pumps depends on propelling water using a spinning impeller or rotor. Two possible mechanisms are used either alone or in combination, so that water is continuously expelled from the impeller by being:

1. deflected by the impeller blades (in propeller type pumps);
2. whirled into a circular path so centrifugal force then carries the water away, in the same way a weight on a string when whirled around and released will fly away.

The earliest practical rotodynamic pumps were developed in the 18th and early 19th century, (Fig. 56). Type A in the figure simply throws water outwards and upwards. Type B is actually a suction centrifugal pump and needs priming in order to initiate pumping; a foot valve is provided to prevent the loss of the priming water when the pump stops. A circular casing is provided to collect the output from the impeller at the delivery level. A pump of this kind is extremely inefficient as the water leaves the impeller with a high velocity which is simply dissipated as lost energy. Pump C, the Massachusetts Pump of 1818, had the collector built around a horizontal shaft so that the velocity of the water could be directed up the discharge pipe and carry it to some height; in some respects this is the fore-runner of the modern centrifugal pump which today is the most commonly used mechanically driven type of pump.

3.8.2 Volute, Turbine and Regenerative Centrifugal Pumps

The early pumps just described differed from modern pumps in one important respect; the water left the pump impeller at high speed and was only effectively slowed down by friction, which gives them poor efficiency and poor performance. The application of an important principle, shown in Fig. 57, led to the evolution of efficient rotodynamic pumps; namely that with flowing fluids, velocity can be converted into pressure and vice-versa. The mechanism is to change the cross section of the passage through which water (or any liquid) is flowinq. Because water is virtually incompressible, if a given flow is forced to travel through a smaller cross section of passage, it can only do so by flowing faster. However pressure is needed to create the force needed to accelerate the mass of water. Conversely, if a flow expands into a larger cross section, it slows down to avoid creating a vacuum and the deceleration of the fluid imposes a force and hence an increase in pressure on the slower moving fluid. It car. be shown (if frictional effects are ignored) that if water flows through a duct of varying cross sectional area, then the head of water (or pressure difference) to cause the change? in velocity from v, to ^v_out, will be H, where:

​

where g is the acceleration due to gravity.

Fig. 56 Early types of centrifugal pumps​

Fig. 57 The relationship between pressure and velocity through both a jet and a diffuser

​

The diagram in Fig. 57 shows how the pressure decreases in a jet as the velocity increases while the reverse occurs in a diffuser which slows water down and increases the pressure. Qualitatively this effect, is obvious to most people. From experience, it is well known that pressure is needed to produce a jet of water; the opposite effect, that smoothly slowing down a jet increases the pressure is less obvious.

When this was understood, it became evident that the way to improve a centrifugal pun; is to throw the water out of an impeller at high speed (in order to add the maximum energy to the water) and then to pass the water smoothly into a much larger cross section by way of a diffuser in which the cross section changes slowly. In this way, some of the velocity is converted into pressure. A smooth and gradual change of cross-section is essential, any sudden change would create a great deal of turbulence which would dissipate the energy of the water instead of increasing the pressure. There are two main methods of doing this, illustrated in Fig. 58 by diagrams A and B, and a more unusual method shown in C.

Diagram A shows the most common, which is the "volute centrifugal" pump, generally known more simply just as a "centrifugal" pump. Here a spiral casing with an outer snail-shell-shaped channel of gradually increasing cross section draws the output from the impeller tangentially, and smoothly slows it down. This allows the water to leave tangentially through the discharge pipe at. reduced velocity, and increased pressure.

Diagram B shows the other main alternative, which is the so-called "turbine centrifugal" or "turbine pump", where a set of smoothly expanding diffuser channels, (six in the example illustrated) serve to slow the water down and raise its pressure in the same way. In the type Of turbine pump illustrated, the diffuser channels also deflect the water into a less tangential and more radial path to allow it to flow smoothly into the annular constant cross-section channel surrounding the diffuser ring, from whore it discharges at the top.

Diagram. C shows the third, lesser known type of centrifugal pump which is usually called a "regenerative pump", but is also sometimes called a "side-chamber pump" or ever, (wrongly) a "turbine pump". Here an impeller with many radial blades turns in a rectangular sectioned annulus; the blades accelerate the water by creating two strong rotating vortexes which partially interact with the impeller around the rim of the pump for about three-quarters of a revolution; energy is steadily added to the two vortexes each time water passes through the impeller; for those familiar with motor vehicle automatic transmissions the principle is similar to that of the fluid flywheel. When the water leaves the annulus it passes through a diffuser which converts its velocity back into pressure. Regenerative pumps are mentioned mainly for completeness; because they have very close internal clearances they are vulnerable to any suspended grit or dirt and are therefore only normally used with clean water (or other fluids) in situations where their unique characteristics are advantageous. They are generally inappropriate for irrigation duties. Their main advantage is a better capability of delivering water to a higher head than other types of single-stage centrifugal pump.

Fig. 58 Centrifugal pump types

​

3.8.3 Rotodynamic Pump Characteristics and Impeller Types

It is not intended to deal with this complex topic in depth, but it is worth running through some of the main aspects relating to pump design to appreciate why pumps are generally quite sensitive to their operating conditions.

All rotodynamic pumps have a characteristic of the kind illustrated in Fig. 16, which gives them a limited range of speeds, flows and heads in which good efficiency can be achieved. Although most pumps will operate over a wider range, if you move far enough from their peak efficiency with any of these parameters, then both the efficiency and output will eventually fall to zero. For example, Fig. 16 shows that if you drive the pump in question with a motor having a maximum speed of say 2000 rpm, there is a maximum flow which can be achieved even at zero head, and similarly there is a head beyond which no flow will occur. The design point is usually at the centre of the area of maximum efficiency.

Since any single rotodynamic pump is quite limited in its operating conditions, manufacturers produce a range of pumps, usually incorporating many common components, to cover a wider range of heads and flows. Because of the limited range of heads and flows any given impeller can handle, a range of sub-sets of different types of impellers has evolved, and it will be shown later there are then variations within each sub-set which can fine tune a pump for different duty requirements. The main sub-sets are shown in Fig. 59, which shows a half-section through the impellers concerned to give an idea of their appearance.

Fig. 59 Typical rotodynamic pump characteristics​

Fig. 60 Axial flow (or propeller) pump

​

It can be seen that pump impellers impose radial, or axial flow on the water, or some combination of both. Where high flows at low heads are required (which is common with irrigation pumps), the most efficient impeller is an axial flow one (this is similar to a propeller in a pipe) - see Fig. 60. Like a propeller, this depends on lift generated by a moving streamlined blade; since in this case the propeller is fixed in a casing, the reaction moves the water. Conversely, for high heads and low flows a centrifugal (radial flow) impeller is needed with a large ratio between its inlet diameter and its outlet diameter, which produces a large radial flow component, as in the left-most type in Fig. 59. In between these two extremes are mixed flow pumps (see also Figs. 61 and 62) and centrifugal pumps with smaller ratios of discharge to inlet diameter for their impellers. The mixed flow pump has internal blades in the impeller which partially propel the water, as with an axial flow impeller, but the discharge from the impeller is at a greater diameter than the inlet so that some radial flow is involved which adds velocity to the water from centrifugal forces that are generated.

Fig. 59 also shows the efficiency versus the "Specific Speed" of the various impeller sub-sets. Specific Speed is a dimensionless ratio which is useful for characterising pump impellers (as well as hydro-turbine rotors or runners). Text books on pump/turbine hydrodynamics cover this topic in greater depth. The Specific Speed is defined as the speed in revolutions per minute at which an impeller would run if reduced in size to deliver 1 litre/sec to a head of 1m and provides a means for comparing and selecting pump impellers and it can be calculated as follows:

​

where n is speed in rpm, Q is the pump discharge in litre/sec and H is the head in metres.

Fig. 61 Surface mounted mixed flow pump​

Fig. 62 Submerged mixed flow pump

​

Fig. 59 indicates the Specific Speeds which best suit the different impeller sub-sets; e.g. an axial flow impeller is best at flow rates of 500-1 000 litre/sec and has a Specific Speed of 5 000-10 000, at heads of about 5m. Specific Speed can be converted back to actual rpm at any given head (H) and flow (Q) as follows:

​

where n is in rpm, N is the Specific Speed from Fig. 59, H is the head in metres, and Q is the flow in litres/sec.

The choice of impeller is not only a function of head and flow but of pump size too; smaller low powered pumps of any of these configurations tend to be somewhat less efficient and they also operate best at lower heads than geometrically similar larger versions.

Fig. 59 also indicates the effect on power requirements and efficiency (marked "kW" and "EFF" respectively) of varying the key parameter of head "H", away from the design point. In the case of a centrifugal pump the small diagram shows that increasing the head reduces the power demand, while in the case of an axial-flow pump, increasing the head increases the power demand. Paradoxically, reducing the head from the design head on a centrifugal pump increases the power demand; the reason for this is that decreasing the head by, say, 10% can increase the flow by 25% - the efficiency may also go down by 10%, and since the power requirement is head times flow divided by efficiency, the new power demand will change from:

​

the ratio of these is 1:1.25, so the power demand will be increased by 25% in this case. Therefore, varying the conditions under which a pump operates away from the design point can have an unexpected and sometimes drastic effect. The use of pumps off their design point is a common cause of gross inefficiency and wasted fuel.

3.8.4 Axial-Flow (Propeller) Pumps

As already explained, an axial-flow (or "propeller") pump propels water by the reaction to lift forces produced by rotating its blades. This action both pushes the water past the rotor or impeller and also imparts a spin to the water which if left uncorrected would represent wasted energy, since it will increase the friction and turbulence without helping the flow of water down the pipe. Axial flow pumps therefore usually have fixed guide vanes, which are angled so as to straighten the flow and convert the spin component of velocity into extra pressure, in much the same way as with a diffuser in a centrifugal pump. Fig. 60 shows a typical axial flow pump of this kind, in which the guide vanes, just above the impeller, also serve a second structural purpose of housing a large plain bearing, which positions the shaft centrally. This bearing is usually water lubricated and has features in common with the stern gear of an inboard-engined motor boat.

Axial flow pumps are generally manufactured to handle 'flows in the range 150 to 1 500m³/h for vertically mounted applications, usually with heads in the ranqe 1.5-3.On. By adding additional stages (i.e. two or more impellers on the same shaft) extra lift up to 10m or so can be engineered.

Because pumps of this kind are designed for very large flows at low heads, it is normal to form the "pipes" in concrete as illustrated, to avoid the high cost of large diameter steel pipes. Most axial flow pumps are large scale devices, which involve significant civil works in their installation, and which would generally only be applicable on the largest land-holdings addressed by this publication. They are generally mainly used in canal irrigation schemes where large volumes of water must be lifted 2-3m, typically from a main canal to a feeder canal.

Small scale propeller pumps are quite successfully improvised but not usually manufactured; ordinary boat propellers mounted on a long shaft have been used for flooding rice paddies in parts of southeast. Asia. The International Rice Research Institute (TRRI) has developed this concept into a properly engineered, portable high volume pumping system, (see Fig. 63); it is designed to be manufactured in small machine shops and is claimed to deliver up to 180m³/h at heads in the range l-4m. This pump requires a 5hp (3kW) engine or electric motor capable of driving its shaft at 3 000rpm; its; length is 3.7m, the discharge tube is 150mm in diameter and the overall mass without the prime mover fitted is 45kg.

Fig. 63 Portable axial flow pump (IRRI)

​

3.8.5 Mixed-Flow Pumps

The mixed-flow pump, as its name suggests, involves something of both axial and centrifugal pumps and in the irrigation context can often represent a useful compromise to avoid the limited lift of an axial flow pump, but still achieve higher efficiency and larger flow rates than a centrifugal volute pump. Also, axial flow pumps generally cannot sustain any suction lift, but mixed-flow pumps can, although of course they are not self-priming.

Fig. 61 shows a surface mounted, suction mixed-flow pump and its installation. Here the swirl imparted by the rotation of the impeller is recovered by delivering the water into a snail-shell volute or diffuser, identical in principle to that of a centrifugal volute pump.

An alternative arrangement more akin to an axial flow pump is shown in Fig. 62. Here what is often called a "bowl" casing is used, so that the flow spreads radially through the impeller, and then converges axially through fixed guide vanes which remove the swirl and thereby, exactly as with axial flow pumps, add to the efficiency. Pumps of this kind are installed submerged, which avoids the priming problems that can afflict large surface suction rotodynamic pumps such as in Fig. 61. The "bowl" mixed-flow pump is sometime called a "turbine" pump, and it is in fact analagous to the centrifugal turbine pump described earlier; the passage through the rotor reduces in cross-section and serves to accelerate the water and impart energy to it, while the fixed guide vanes are designed as a diffuser to convert speed into pressure and thereby increase both the pumping head and the efficiency. A number of bowl pumps can be stacked on the same shaft to make a multi-stage turbine pump, and these are quite commonly used as borehole pumps due to their long narrow configuration. Mixed-flow bowl pumps typically operate with flows from 200-12 000m³/h over heads from 2-10m. Multiple stage versions are often used at heads of up to about 40m.

3.8.6 Centrifugal Pumps

i. Horizontal shaft centrifugal pump construction

These are by far the most common generic type of electric or engine powered pump for small to medium sized irrigation applications. Fig. 64 shows a typical mass-produced volute-centrifugal pump in cross section. In this type of pump the casing and frame are usually cast iron or cast steel, while the impeller may be bronze or steel. Critical parts of the pump are the edges of the entry and exit to the impeller as a major source of loss is back-leakage from the exit of the impeller around the front of it to the entry. To prevent this, good quality pumps, including the one in the diagram, have a closely fitting wear ring fitted into the casing around the front rim of the impeller; this is subject to some wear by grit or particulate matter in the water and can be replaced when the clearance becomes large enough to cause significant loss of performance. However, many farmers probably do not recognize wear of this component as being serious and simply compensate by either driving the pump faster or for longer each day, both of which waste fuel or electricity. Another wearing part is a stuffing box packing where the drive shaft emerges from the back of the impeller casing. This needs to be periodically tightened to minimize leakage, although excessive tightening increases wear of the packing. The packing is usually graphited asbestos, although graphited PTFE is more effective if available. The back of the pump consists of a bearing pedestal and housing enclosing two deep-groove ball-bearings. This particular pump is oil lubricated, it has a filler, dip-stick and drain plug. Routine maintenance involves occasional changes of oil, plus more frequent checks on the oil level. Failure to do this leads to bearing failure, which if neglected for any time allows the shaft to whirl and damage the impeller edges.

Fig. 64 Typical surface mounted pedestal centrifugal pump

​

ii . Centrifugal pump installations

Figs. 65 and 66 show two alternative typical low lift centrifugal pump installations; the simplest is the suction installation of Fig. 65. As mentioned earlier in Section 2.1.5, centrifugal pumps are limited to a maximum in practice of about 4-5m suction lift at sea level (reducing to around 2m suction lift at an altitude of 2 000m, and further reduced if a significant length of suction pipe is involved; otherwise problems are almost certain to be experienced in priming the pump, retaining its prime, etc. A foot valve is a vital part of any such installation as otherwise the moment the pump stops or slows down, all the water in the pipeline will run back through the pump making it impossible to restart the pump unless the pipeline is first refilled. Also, if water flows back through the pump, it car: run backwards and possibly damage the electrical system.

If the delivery pipeline is long, it is also important to have another check valve (non-return valve) at the pump discharge to the pipeline. The reason for this is that if for any reason the pump suddenly stops, the flow will continue until the pressure drops enough to cause cavitation in the line; when the upward momentum of the water is exhausted, the flow reverses and the cavitation bubbles implode creating severe water hammer. Further severe water hammer occurs when the flow reverses causing the footvalve to slam shut. The impact of such events has been known to burst a centrifugal pump's casing. The discharge check valve therefore protects the pump from any such back surge down the pipeline.

Fig. 65 Surface mounted centrifugal pump installation​

Fig. 66 Below-surface (sump) centrifugal pump installation​

Fig. 67 Various types of centrifugal pump impellers​

Fig. 68 Effect of direction of curvature of vanes of centrifugal pump impellers

​

In many cases there is no surface mounting position low enough to permit suction pumping. In such cases centrifugal pumps are often placed in a sump or pit where the suction head will be small, or even as in Fig. 66 where the pump is located below the water level. In the situation illustrated a long shaft is used to drive the pump from a surface mounted electric motor; (to keep the motor and electrical equipment above any possible flood level).

iii. Centrifugal pump impeller variations

The component that more than anything else dictates a centrifugal pump's characteristics is its impeller. Fig. 67 shows some typical forms of impeller construction. Although the shape of an impeller is important, the ratio of impeller exit area to impeller eye area is also critical (i.e. the change of cross section for the flow through the impeller), and so is the ratio of the exit diameter to the inlet diameter. A and B in the figure are both open impellers, while C and D are shrouded impellers. Open impellers are less efficient than shrouded ones, (because there is more scope for back leakage and there is also more friction and turbulence caused by the motion of the open blades close to the fixed casing), but open impellers are less prone to clogging by mud or weeds. But shrouded impellers are considerably more robust and less inclined to be damaged by stones or other foreign bodies passing through. Arguably, open impellers are less expensive to manufacture, so they tend to be used on cheaper and less efficient pumps; shrouded impellers are generally superior where efficiency and good performance are important.

Also in Fig. 67, A and C are impellers for a single-suction pump, while B and D are for a double-suction pump in which water is drawn in symmetrically from both sides of the impeller. The main advantage of a double-suction arrangement is that there is little or no end thrust on the pump shaft, but double suction pumps are more complicated and expensive and are uncommon in small and medium pump sizes.

The shape of the impeller blades is also of importance. Some factors tend to flatten the HQ curve for a given speed of rotation, while others Steepen it. Fig. 68 shows the effect of backward raked, radial and forward raked blade tips; the flattest curve is obtained with the first type, while the last type actually produces a maximum head at the design point. Generally the flatter the HQ curve, the higher the efficiency, but the faster the impeller has to be driven to achieve a given head. Therefore impellers producing the most humped characteristics tend to be used when a high head is needed for a given speed, but at some cost in reduced efficiency.

iv. Series and parallel operation of centrifugal pumps

Where a higher head is needed than can be achieved with a single pump, two can be connected in series as in Fig. 69 A, and similarly, if a greater output is needed, two centrifugal pumps may be connected in parallel as in Fig. 69 B. The effects of these arrangements on the pump characteristics are illustrated in Fig. 69 C, which shows the changes in head, discharge and efficiency that occur as a percentage of those for a single pump operating at its design point. It is clear that series connection of pumps has no effect on efficiency or discharge but doubles the effective head. Parallel operation does not however normally double the discharge compared to a single pump, because the extra flow usually causes a slight increase in total head (due to pipe friction), which will move the operating point enough to prevent obtaining double the flow of a single pump.

Fig. 69 Combining centrifugal pumps in series or parallel

​

3.8.7 Multi-stage and Borehole Rotodynamic Pumps

Where high heads are needed, the primary means to achieve this with a single impeller centrifugal pump are either to drive the impeller faster or to increase its diameter. In the end there are practical limits to what can be don in this way, so that either single impeller pumps can be connected in series, or a more practical solution is to use a multiple impeller pump in which the out put from it from one impeller feeds directly, through suitable passages in the casing, to the next, mounted on the same shaft. Fig. 70 shows a 5 stage borehole pump (where limitations on the impeller diameter are caused by the borehole, making multi-staging an essential means to obtain adequate heads). Fig. 44 includes a three stage centrifugal pump, coupled to a turbine as a prime-mover, as another example of multi-staging.

Surface-mounted multi-stage pumps are probably only likely to be of relevance to irrigation in mountainous areas since there are few situations elsewhere where surface water needs to be pumped through a high head. More important from, the irrigation point of view is the vertical shaft multi-stage submersible borehole pump which has an integral submerged electric motor directly coupled to the pump below the pump as in the example of Fig. 70, However, it is possible to get bare-shaft multi-stage borehole pumps in which the pump is driven from the surface via a long drive shaft supported by spider bearings at regular intervals down the rising main; see Fig. 134 (b) or with the motor arranged as for the centrifugal pump in Fig. 66, but. with a vertically mounted multi-stage pump in either a sump or well.

In recent years numerous, reliable, submersible electric pumps have evolved; Fig. 70. Section 4.6 discusses in more detail the electrical implications and design features of this kind of motor. Extra pump stages can be fitted quite easily to produce a range of pumps to cover a wide spectrum of operating conditions. The pump in Fig. 70 is a 5 stage mixed-flow type, and the same figure also shows how, simply by adding extra stages (with increasingly powerful motors) a whole family of pumps can be created capable in the example illustrated of lifting water from around 40m with the smallest unit to around 245m with the most powerful; the efficiency and flow will be similar for all of these options. Only the head and the power rating will vary in proportion to the; number of stages fitted.

Finally, Fig. 71 and Fig. 134 (a) show borehole installations with submersible electric pumps. The pump in Fig. 71 has level sensing electrodes clipped to the rising main, which can automatically switch it off if the level falls too low.

Fig. 70 Multi-stage submersible electric borehole pumps​

Fig. 71 Schematic of complete electric submersible borehole pumping installation

​

3.8.8 Self-priming Rotodynamic Pumps

Rotodynamic pumps, of any kind, will only start to pump if their impellers are flooded with water prior to start-up. Obviously the one certain way to avoid any problem is to submerge the pump in the water source, but this is not always practical or convenient. This applies especially to portable pump sets, which are often important for irrigation, but which obviously need to be drained and re-primed every time they are moved to a new site.

If sufficient water is present in the pump casing, then even if the suction pipe is empty, suction will be created and water can be lifted. A variety of methods are used to fill rotodynamic pumps when they are mounted above the water level. It is, however, most important to note that if the suction line is empty but the delivery line is full, it may be necessary to drain the delivery line in order to remove the back pressure on the pump, to enable it to be primed. Otherwise it will be difficult if not impossible to flush out the air in the system. One way to achieve this is to fit a branch with a hand valve on it at the discharge, which can allow the pump to be "bled" by providing an easy exit for the air in the system.

The most basic method of priming is to rely on the footvalve to keep water in the system. The system has to be filled initially by pouring water into the pipes from a bucket; after that it is hoped that the footvalve will keep water in the system even after the pump is not used for some time. In many cases this is a vain hope, as footvalves quite often leak, especially if mud or grit is present in the water and settles between the valve and its seat when it attempts to close. Apart from the nuisance value when a pump loses its prime, many pumps suffer serious damage if run for any length of time while dry, as the internal seals and rubbing faces depend on water lubrication and will wear out quickly when run dry. Also, a pump running dry will tend to overheat; this will melt the grease in the bearings and cause it to leak out, and can also destroy seals, plastic components or other items with low temperature tolerance.

The two most common methods for priming surface-mounted, engine driven suction centrifugal pumps are either by using a small hand pump on the delivery line as illustrated in Fig. 72, (this shows a diaphragm priming pump which has particularly good suction capabilities) or an "exhaust ejector" may be used; here suction is developed by a high velocity jet of exhaust from the engine, using similar principles to those illustrated in Fig. 57 and described in more detail in Section 3.8.9 which follows.

Several alternatie methods of priming surface suction pumps may be commonly improvized. For example, a large container of water may be mounted above the pump level so water can be transferred between the pump and the tank via a branch from the delivery line with a valve in it. Then when the pump has to be restarted after the pipe-line has drained, the valve can be opened to drain the tank into the pump and suction line. Even the worst footvalves leak slowly enough to enable the system to be started, after which the tank can be refilled by the pump so as to be ready for the next start.

Alternatively, a large container can be included in the suction line, mounted above the level of the pump, which will always trap enough water in it to allow the pump to pull enough of a vacuum to refill the complete suction line. Care is needed in designing an installation of this kind, to avoid introducing air-locks in the suction line.

Fig. 72 Direct-coupled air-cooled diesel engine and pump installation with hand-operated diaphragm pump for priming

​

Yet another simple method to use, but only if the delivery line is long enough to carry a sufficient supply of water, is to fit a hand-valve immediately after the pump discharge (instead of a non-return valve) so that when the pump is turned off, the valve can be manually closed. Then the opening of this valve will refill the pump from the delivery line to ensure it is flooded on restarting.

Sometimes the most reliable arrangement is to use a special "self-priming" centrifugal pump (Fig. 73). Here, the pump has an enlarged upper casing with a baffle in it. When the pump and suction line are empty, the pump casing has to be filled with water from a bucket through the filler plug visible on top. Then when the pump is started, the water in the casing is thrown up towards the discharge and an eye is formed at the hub of the impeller which is at low pressure; until water is drawn up the suction pipe the water discharged from the top of the pump tends to fall back around the baffle and some of the entrained air carries on up the empty discharge pipe. The air which is discharged is replaced by water drawn up the suction pipe, until eventually the suction pipe fills completely and the air bubble in the eye of the impeller is blown out of the discharge pipe. Once all the air has been expelled, water ceases to circulate within the pump and both channels act as discharge channels. A check valve is fitted to the inlet of the pump so that when the pump is stopped it remains full of water. Then even if the foot valve on the suction line leaks and the suction line empties, the water trapped in the casing of the pump will allow the same self-priming function as described earlier to suck water up the suction line. Hence, pumps of this kind only need to be manually filled with water when first starting up after the entire system has been drained.

Fig. 73 Self-priming centrifugal pump

​

3.8.9 Self-Priming Jet Pumps

An alternative type of self-priming centrifugal pump uses the fact that if water is speeded up through a jet, it causes a drop in pressure (see Section 3.8.2). Here the pump is fitted into a secondary casing which contains water at. discharge pressure, (see Fig. 74). A proportion of the water from this chamber is bled back to a nozzle fitted into the suction end of the pump casing and directed into the eye of the impeller. Once the pump has been used once (having been manually primed initially) it remains full of water so that on start up the pump circulates water from the discharge through the jet and back into the suction side. As before, air is sucked through and bubbles out of the discharge, while (until the pump primes) the water falls back and recirculates. The jet causes low pressure in the suction line and entrains air which goes through the impeller and is discharged, hence water is gradually drawn up the suction line. As soon as all the air is expelled from the system, most of the discharge goes up the discharge line, but a proportion is fed back to the nozzle and increases the suction considerably compared with the effect of a centrifugal impeller on its own. Therefore, this kind of pump not only pulls a higher suction lift than normal, but the pump can reliably run on "snore" (i.e. sucking a mixture of air and water without losing its prime). This makes it useful in situations where shallow water is being suction pumped and it is difficult to obtain sufficient submergence of the footvalve, or where a water source may occasionally be pumped dry.

This jet pump principle can also be applied to boreholes as indicated in Fig. 75. An arrangement like this allows a surface-mounted pump and motor to "suck" water from depths of around 10-20m; the diffuser after the jet serves to raise the pressure in the rising main and prevent cavitation. Although the jet circuit commonly needs 1.5-2 times the flow being delivered, and is consequently a source of significant power loss, pumps like this are sometimes useful for lifting sandy or muddy water as they are not so easily clogged as a submerged pump. In such cases a settling tank is provided on the surface between the pump suction and the jet pump discharge to allow the pump to draw clearer water.

Fig. 74 Schematic of a surface-suction jet pump

​

The disadvantages of jet pumps are, first, greater complexity and therefore cost, and second, reduced efficiency since power is used in pumping water through the jet, (although some of this power is recovered by the pumping effect of the jet). Obviously it is better to use a conventional Centrifugal pump in a situation with little or no suction lift, but where Suction pumping is essential, then a self-priming pump of this kind can offer a successful solution.

Fig. 75 Borehole jet pump installation​

 

3.9 AIR LIFT PUMPS

The primary virtue of air lift pumps is that they are extremely simple. A rising main, which is submerged in a well so that more of it is below the water level than above it, has compressed air blown into it at its lowest point (see Fig. 76). The compressed air produces a froth of air and water, which has a lower density than water and consequently rises to the surface. The compressed air is usually produced by an engine driven air compressor, but windmill powered air compressors are also used. The principle of it is that an air/water froth, having as little as half the density of water, will rise to a height above the water level in the well approximately equal to the immersed depth of the rising main. The greater the ratio of the submergance of the rising main to the static head, the more froth will be discharged for a given supply of air and hence the more efficient an air lift pump will be. Therefore, when used in a borehole, the borehole needs to be drilled to a depth more than twice the depth of the static water level to allow adequate submergence.

Fig. 76 Air lift pump (schematic)

​

The main advantage of the air lift pump is that there are no mechanical below-ground components, so it is essentially simple and reliable and can easily handle sandy or gritty water. The disadvantages are rather severe; first, it is inefficient as a pump, probably no better, at best, than 20-30% in terms of compressed air energy to hydraulic output energy, and this is compounded by the fact that air compressors are also generally inefficient. Therefore the running costs of an air lift pump will be very high in energy terms. Second, it usually requires a borehole to be drilled considerably deeper than otherwise would be necessary in order to obtain enough [submergence, and this is generally a costly exercise. This problem is obviously less serious for low head applications where the extra depth [required would be small, or where a borehole needs to be drilled to a considerable depth below the static water level anyway to obtain sufficient inflow of water.

3.10 IMPULSE (WATER HAMMER) DEVICES

These devices apply the energy of falling water to lift a fraction of the flow to a higher level than the source. The principle they work by is to let the water from the source flow down a pipe and then to create sudden pressure rises by intermittently letting a valve in the pipe slam shut. This causes a "water hammer" effect which results in a sudden sharp rise in water pressure sufficient to carry a small proportion of the supply to a considerably higher level.


They therefore are applicable mainly in hilly regions in situations where there is a stream or river flowing quite steeply down a valley floor, and areas that could be irrigated which are above the level that can be commanded by small channels contoured to provide a gravity supply.
The only practical example of a pump using this principle is the hydraulic ram pump, or "hydram", which is in effect a combined water-powered prime mover and pump. The hydraulic ram pump is mechanically extremely simple, robust and ultra reliable. It can also be reasonably efficient. However in most cases the output is rather small (in the region of 1-3 litre/sec) and they are therefore best suited for irrigating small-holdings or single terrace fields, seedlings in nurseries, etc.


Hydraulic rams are described more fully in Section 4.9.? dealing with water powered pumping devices.

3.11 GRAVITY DEVICES

3.11.1 Syphons

Strictly speaking syphons are not water-lifting devices, since, after flowing through a syphon, water finishes at a lower level than if started. However syphons can lift water over obstructions at a higher level than the source and they are therefore potentially useful in irrigation. They also have a reputation for being troublesome, and their principles are often not well understood, so it. is worth giving them a brief review.


Fig. 77 A to C shows various syphon arrangements. Syphons are limited to lifts of about 5m at sea level for exactly the same reasons relating to suction lift for pumps. The main problem with syphons is that due to the low pressure at the uppermost point, air can come out of solution and form a bubble, which initially causes an obstruction and reduces the flow of water, and which can grow sufficiently to form an airlock which stops the flow. Therefore, the syphon pipe, which is entirely at a sub-atmospheric pressure, must be completely air-tight, Also, in general, the faster the flow, the lower the lift and the more perfect the joints, the less trouble there is likely to be with air locks.


Starting syphons off can also present problems. The simplest syphons can be short lengths of flexible plastic hose which may typically be used to irrigate a plot by carrying water from a conveyance channel over a low bund; it is well known that all that needs to be done is to fill the length of hose completely by submerging it in the channel and then one end can be covered by hand usually and lifted over the bund, to allow syphoning to start. Obviously, with bigger syphons, which are often needed when there is an obstruction which cannot easily be bored through or removed, or where there is a risk of leakage from a dam or earth bund if a pipe is buried in it, simple techniques like this cannot be used.

Fig. 77 Syphon arrangements

​

In Fig. 77 A, a non-return valve or foot-valve is provided on the intake side of the syphon, and an ordinary gate valve or other hand-valve at the discharge end. There is a tapping at the highest point of the syphon which can be isolated, again with a small hand valve. If the discharge hand valve is closed and the top valve opened, it is possible to fill the syphon completely with water; the filler valve is then closed, the discharge valve opened and syphoning will commence.


Diagram B is similar to A except that instead of filling the syphon with water to remove the air, a vacuum pump is provided which will draw out the air. Obviously this is done with the discharge valve closed. The vacuum pump can be a hand pump, or it could be a small industrial vacuum pump. Once the air is removed, the discharge valve can be opened to initiate syphoning.


Diagram C shows a so-called "reverse" syphon, used for example where a raised irrigation channel needs to cross a road. Reverse syphons operate at higher than atmospheric pressure and there is no theoretical limit to how deep they can go, other than that the pipes must withstand the hydrostatic pressure and that the outflow must be sufficiently lower than the inflow to produce the necessary hydraulic gradient to ensure gravity flow.

3.11.2 Qanats and Foggara

Qanats, as they are known in Farsi or Foggara (in Arabic), are "man-made springs" which bring water out to the surface above the local water table, but by using gravity. Like syphons they are not strictly water lifting devices, but they do offer an option in lieu of lifting water from a well or borehole in order to provide irrigation. They have been used successfully for 2 000 years or more in Iran, and for many centuries in Afghanistan, much of the Middle East and parts of North Africa.


Fig. 78 shows a cross-section through a qanat; it can be seen that the principle used exploits the fact that the water table commonly rises under higher ground. Therefore, it is possible to excavate a slightly upward sloping tunnel until it intercepts the water table under higher ground possibly at some distance from the area to be irrigated. It is exactly as if you could take a conventional tube well and gradually tip it over until the mouth was below the level of the water table, when, clearly water would flow out of it continuously and without any need for pumping.


Qanats are typically from one to as much as 50 kilometres long, {some of the longest are in Iran near Isfahan). They are excavated by sinking wells every 50 to 100m and then digging horizontally to join the bases of the wells, starting from the outflow point. Traditional techniques are used, involving the use of simple hand tools, combined with sophisticated surveying and tunnelling skills. Many decades are sometimes needed to construct a long qanat, but once completed they can supply water at little cost for centuries. The surface appearance of a qanat is distinctive, consisting of a row of low crater-like earth bunds (or sometimes a low brick wall) surrounding each well opening; this is to prevent flash floods from pouring down the well and washing the sides away. The outflow from a qanat usually runs into a cultivated oasis in the desert, resulting from the endless supply of water.

Fig. 78 Cross-section through a Qanat

​

Efforts have been made in Iran to mechanize qanat construction, but without great success, although in some cases qanats are combined with engine powered lift pumps in that the qanat carries water more or less horizontally from under a nearby hill possessing a raised water table to a point on level ground above the local water table but below the surface, where a cistern is formed in the ground. A diesel pump is then positioned on a ledge above the cistern to lift the water to the surface.

 

Cisterns for Drinking Water Water
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• Cisterns for Drinking Water Water, problems, maintenance, advice
• Indoor attic and basement or crawl space cisterns
• Outdoor cisterns as a source of drinking water
• Acceptability of cisterns for drinking water if HUD financing
• Types of wells and water supply systems and what to watch out for with each

[SIZE=-2]Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.[/SIZE] <ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="aswift_3_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins>
<ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="aswift_4_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins> This article describes the use of cisterns as drinking water sources. We provide advice about what to do when things go wrong. Readers of this document should also see Water Tank Types and before assuming that a water problem is due to the well itself, see Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost. Also see [SIZE=-1]PLASTIC CONTAINERS, TANKS, TYPES[/SIZE] and see [SIZE=-1]WATER TANK SAFETY[/SIZE].

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Cisterns and How to use them for Drinking Water Storage

A cistern is basically a water reservoir of any kind which is used to accumulate and store water for future use. Cisterns are usually constructed close to the building which will use their water, sometimes even inside it. Traditionally and still in some parts of the world people direct roof runoff from the rainy season into a cistern where it is stored for use during dry periods.

Water from a cistern is typically pumped out by hand, drained by gravity, or it may be pumped by an electric pump such as a one line jet pump. The photo at page top shows an abandoned cistern which had been built abutting a home. Interestingly the owner broke through into the cistern from the basement and drilled a modern steel casing well right in the bottom of the cistern - some of the new equipment is also visible.

Cisterns to store water for drinking or agricultural purposes are widely used in dry areas where rainwater runoff may be stored for future use. However all water storage cisterns that are to be used for drinking or potable water supplies are at risk of contamination either from external sources or from bacterial growth during the water storage interval.

Cisterns may be located inside or outside of a building, and may be above ground or below ground level. Our photograph of a concrete cistern (above left) was taken in the basement of a 1920's home in New York state.

Attic Cisterns & Water Pressure Tanks

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Cisterns in attics are an open-type water storage reservoir or a water pressure boosting system similar in function to rooftop cisterns and water storage tanks.

A cistern was generally placed where it could be fed by gravity from roof or surface runoff, but any indoor open topped reservoir of water could be called a cistern.

Attic Cisterns or water tanks are installed in some buildings to perform the same function as rooftop-mounted water tanks. Other smaller attic containers that look like a water reservoir may have been just an expansion tank for the heating boiler system.

</td> </tr> </tbody></table> Basement & Indoor Cisterns in Older Homes

<table cellpadding="0" cellspacing="0"><tbody><tr><td valign="TOP" width="30%"> </td><td valign="TOP" width="30%"> </td> </tr></tbody></table> In the U.S. cisterns were often located in the basement of a (pre-1900) home. This cistern is located in the basement of a pre-1900 home in New York. Later owners broke open a passage into the basement cistern and now use it for storage. This cistern was originally filled by downspouts directing roof runoff into the basement.
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Cisterns inside older buildings can be tricky to spot - the cistern may have been partly demolished, such as in photos shown above, or the cistern may be a walled structure whose top is just below the joists of the building's first floor, as we see in the photos just below.

A tip that led to our discovery of this cistern was an unexplained drainpipe protruding to outside through a building wall. We traced the drain to a nearly-hidden basement cistern where it handled cistern overflow.

</td></tr></tbody></table> In a seasonally damp climate such as New York, an in-use basement cistern would certainly be a likely source of unwanted building moisture

Open Water Tanks Indoors

An open indoor water tank (photos below) can also function as an intermediate limited-quantity water storage tank for a building fed by gravity from an up-hill spring or artesian well.
<table cellpadding="0" cellspacing="0"><tbody><tr><td valign="TOP" width="30%"> </td> <td valign="TOP" width="30%"> </td> </tr></tbody></table> At some locations there is an up-hill or rooftop water source which is fed into the building entirely by gravity. The open top water tank in these photos used a simple float valve to let water into this storage tank. Where such intermediate storage tanks, perhaps fed by an uphill spring, were located in the upper floors of a building they fed water to building piping where it could flow by gravity when a water tap was opened.
Our photographs show that this indoor water tank has rusted-through and is no longer functional, but the float assembly (photo above-right) makes clear how the tank worked.

Rooftop Water Storage Systems

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Rooftop water storage tanks or cisterns may be filled by pumping from a well, pumping to the building top from a water main in the street, or filled by street water pressure if the building is not more than a few stories high.
The rooftop tank provides good water pressure for plumbing fixtures in the building below, and in areas of limited water supply it also serves as water storage. Our photograph of a large rooftop water storage tank (left) was taken in Manhattan and was constructed of wood with iron bindings.
This water storage tank is used to provide good water pressure to fixtures in the multi-story building it serves.
Water is pumped or delivered by municipal water pressure to the rooftop tank from its municipal source, then redistributed at good pressure to the points of use in the building below.
When passing through New York City, look at rooftops and you'll often see these tanks still in use.
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Rooftop water storage tanks In some areas, Mexico, for example, rooftop water reservoirs are supplied intermittently with water from a water main in the street.
The rooftop water storage tanks in this photograph from San Miguel de Allende in Guanajuato are being used both to accumulate a water reservoir so that water is always available to the building, and to supply water at a useful pressure.
On low buildings or where the water tank is not high above the point of use, some systems install a water pressure booster pump and tank.
We discuss water pressure booster pump and tank systems at [SIZE=-1]
PUMP, WATER PRESSURE BOOSTING[/SIZE]

</td></tr></tbody></table> Free-standing Water Tanks at Ground Level

Here we show two types of freestanding above-ground water storage tanks, at the Taboada Hot Springs (Guanajuato, Mexico, photo at left), and in Dutchess County, NY (photo below right).
<table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%"> </td> </tr></tbody></table> <table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%" height="275">
Our sketch (left) shows how an elevated and independently-supported water storage and pressure might be constructed, though this particular sketch has the tank next to a well. See details at CISTERNS.

</td></tr></tbody></table> Rainwater Storage Tanks & Cisterns

Outdoor Cisterns, are often located in the basement or courtyard of buildings where they collect rainwater for future use. In arid areas such as the U.S. Southwest and parts of Mexico, very large cisterns are often placed in a courtyard where they collect rainwater for use during the dry season.
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In a seasonally damp climate such as New York, an in-use basement cistern would certainly be a likely source of unwanted building moisture and would thus be a risk for problematic mold growth.
In arid areas such as the U.S. Southwest and parts of Mexico, very large cisterns are often placed in a courtyard where they collect rainwater for use during the dry season.
The above-ground water cistern storage tank shown in our photo (left) is located in Mexico and is discussed at [SIZE=-1]PASSIVE SOLAR HOME, LOW COST[/SIZE].

Rainwater for this cistern is collected from a near-flat rooftop and channeled to a large fiberglass holding tank - the blue tank in our photograph, (above left). Piping also permits directing water into this tank from a well-fed cistern located atop the concrete block tower). The tower's height provides water pressure to the building. Currently water is taken out of the bottom of this tank by a simple tank drain valve and hose attachment; to supply this water upwards to the building plumbing fixtures or perhaps to the cistern, a small electric pump will be installed.

</td></tr></tbody></table> Advice for using Cisterns for Water Supply

• Safety: be sure the cistern is of sound construction and that it is safely covered or protected from someone falling into the cistern or from a child climbing into it. Also see details at [SIZE=-1]WATER TANK SAFETY[/SIZE].
• Direct roof runoff, not surface runoff, into the cistern. Some clever roof runoff management systems direct the first roof runoff onto the ground, permitting dust and debris from the roof surface to be disposed-of before the remaining roof runoff is directed into the cistern for water storage. Other water sources may be used to supply cisterns, including even local or municipal water supplies. In this case the cistern is being used as a backup or off-peak water supply source.
• Do not assume that water stored in a cistern is potable prior to filtering and treatment. The water should be tested for contaminants before used for drinking; it's fine to use cistern water for watering plants or lawns if that water usage is suitable and permitted by other conditions.
• Do not install an open, un-covered cistern in a building where moisture from the cistern could cause a mold or rot problem.
• Plastic Water Storage Tank Health & Safety: some water storage tanks are made of plastic polyethylene terephthalate aka PET. PET plastic water tanks may be a health risk to consumers: Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research on this topic. Proposed mechanisms include leaching of phthalates as well as leaching of antimony.[14] Other authors have published evidence indicating that it is quite unlikely that PET yields endocrine disruptors.[15] - Web search 6/27/2010 Wikipedia.
  We discuss how to identify the type of plastic used in a water tank and the health and safety of different types of plastic tanks in detail at
  • [SIZE=-1]WATER TANK SAFETY
    Water Pump Safety
    Water Storage Tank Health & Safety
    Types of Plastic Water Tanks
    How to ID Type of Plastic Water Tank
    Water Storage Tank Safety Checklists[/SIZE]
  • [SIZE=-1]
    [/SIZE]
• Provide access to the cistern for inspection and cleaning
• Pumps for cisterns: if you intend to rely on an electrical pump to move water from the cistern to its point of use during bad weather and possible power outage your pump will need a backup source of electricity.
• Springs as Water Supply what are they, can they be sanitary and safe?

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Attic Cisterns or water tanks are installed in some buildings to perform the same function as rooftop-mounted water tanks. This little attic reservoir found in the Justin Morrill historic home.
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Attic expansion tanks and pressure relief systems Don't confuse an old heating system attic-mounted expansion tank for a water tank however. These are not potable water storage systems.
The heating system expansion tank will be connected to the heating system radiators or basement boiler and may have a simple overflow pipe to permit excessive water (or system pressure) to spill outside.
Heating systems with this equipment installed may not have a modern pressure and temperature relief valve.
Attic expansion tank systems used on heating boilers are potentially less safe than installing a relief valve right on the boiler, since the attic-located pressure relief system is located so remote from the heating boiler.

</td></tr></tbody></table> Is a Cistern an Acceptable Water Supply for HUD Financing?

<table cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td valign="TOP" width="70%"> </td> </tr></tbody></table> Cisterns and HUD financing: HUD Handbook 4150.2 Section 3-6 indicates that properties served by cisterns are not acceptable for mortgage insurance. However, the HOCs have the authority to consider waivers in areas where cisterns are typical.
Our photo (above left) shows a hybrid system: this outdoor cistern is filled by pumping from an open casing in a drilled well that was inserted in the bottom of a dug well that went "dry" (photo, above right).
As will be apparent to readers, both the open top of this cistern and the open casing in the bottom of the dug well are sources of water contamination.
See [SIZE=-1]WELL CLEARANCE DISTANCES[/SIZE] for more information about cisterns, well and water source clearances from potential pollutant sources, and possible exceptions that can permit use of cisterns for drinking water supply.

 

Plastic Bottles, Containers, Tanks: Plastic Types, Plastic Contaminants
[SIZE=-1]InspectAPedia^® - ShareThis [/SIZE]

• Names & characteristics of types of plastics used for containers
• Definition of plastic recycling codes 1-7
• How to Use the Plastic Recycling Code to Identify The Type of Plastic Tank or Container
• Typical uses & recycling procedures for HDPE - High Density Polyethylene, K-SBC - K-Resin SBC plastic, LDPE - Low Density Polyethylene, PCR - Post-Consumer Resin, Polycarbonate plastic, PET - Polyethylene terephthalate, PP - Polypropylene plastic, PS - Polystyrene plastic, & PVC - Polyvinyl Chloride plastic
• PET Plastic Water Storage Tank Health, Safety, & Sanitation Advice
• BPA-Bisphenol-A - containing plastics hazard summary

[SIZE=-2]Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.[/SIZE] <ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="google_ads_frame4_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins>
<ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="google_ads_frame5_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins> This article describes the types of plastics used in bottles, containers, and tanks, including for water storage. We identify possible contaminants that may leach into drinking water from some types of plastic.

Also see [SIZE=-1]Bisphenol-A, BPA[/SIZE] and [SIZE=-1]PLASTIC & FIBERGLASS TANKS, HDPE[/SIZE] and see safety and health advice regarding cisterns and water storage tanks, including plastic water tanks, discussed at [SIZE=-1]WATER TANK SAFETY[/SIZE]. Other plastics used in construction that have been subject of failures and/or litigation: see [SIZE=-1]PLASTIC HEATER VENT[/SIZE] and [SIZE=-1]PLASTIC PIPING[/SIZE].

© Copyright 2010 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left.

Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

Types of Plastics Used for Bottles, Containers & Tanks

• HDPE - High Density Polyethylene - the most widely used material for plastic bottles, HDPE is supplied in FDA-approved food-grade products. It does not withstand temperatures over 160 degF. Also see [SIZE=-1]PLASTIC & FIBERGLASS TANKS, HDPE[/SIZE].
• K-SBC - K-Resin SBC plastic containers, a styrene derivative, used for containers but not for oils or solvents.
• LDPE - Low Density Polyethylene - similar to HDPE, less rigid, more translucent, more costly, not used for water storage tanks.
• PCR - Post-Consumer Resin, reclaimed plastic HDPE storage containers.
• Polycarbonate plastic containers made with biphenyl-A (a hormone disruptor)(baby bottles, microwave ovenware, eating utensils)
• PET - Polyethylene terephthalate (PETE, PETP, PET-P) is a thermoplastic polymer polyester plastic resin. plastic water tanks may be a health risk to consumers
• PP - Polypropylene plastic storage containers, used for foods, tolerates higher temperatures.
• PS - Polystyrene plastic storage containers, used with dry products, not for water storage.
• PVC - Polyvinyl Chloride plastic bottles or storage tanks, used for bottled oils and soaps, like HDPE it does not withstand high temperatures over 160 degF.

So What Plastic Was Used to Make My Water Bottle, Container, or Water Tank?



Use the Plastic Recycling Code to Identify The Type of Plastic Tank or Container

How do you identify what kind of plastic was used to make your water or other storage tank or even your plastic water bottle or food container?
Use this simple guide to plastic recycling codes and look for the recycling indicator or label on your plastic container. Our photo (left) shows an image of the plastic recycling code #7.
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#1 plastics - PET / PETE (polyethylene terephthalate) One-time use (do not refill plastic water bottles carrying this recycling mark)
</td> </tr> </tbody></table> <table cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td valign="TOP" width="70%">
#2 plastics - HDPE (high density polyethylene) (Nalgene Corp. produces HDPE water bottles) - also see [SIZE=-1]PLASTIC & FIBERGLASS TANKS, HDPE[/SIZE]
</td> </tr> </tbody></table> <table cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td valign="TOP" width="70%">
#3 plastics - PVC (polyvinyl chloride)
</td> </tr> </tbody></table> <table cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td valign="TOP" width="70%">
#4 plastics - LDPE (low density polyethylene)
</td> </tr> </tbody></table> <table cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td valign="TOP" width="70%">
#5 plastics - PP (polypropylene)
</td> </tr> </tbody></table> <table cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td valign="TOP" width="70%" height="79">
#6 plastics - PS (polystyrene)
</td> </tr> </tbody></table> <table cellpadding="0" cellspacing="0" width="100%"> <tbody><tr> <td valign="TOP" width="70%">
#7 plastics - Plastics-other (includes polycarbonate plastics) (Nalgene Corp. produces lexan water bottles) - may leach BPA - Bisphenol-A (health concerns).
FYI: while BPA-containing plastic containers are expected to carry the #7 recycling label, according to the New York Times (7 Sept. 2010), not all plastics labeled with recycling symbol #7 are in fact BPA-containing.

</td> </tr> </tbody></table> PET Plastic Water Storage Tank Health, Safety, & Sanitation Advice



Question:
I've been unable to find on-line information about the safety of using common 1500 gallon plastic water tanks to hold drinking water. Our tank is shaded, but summers are warm and the water often sits in the tank for weeks, especially when we are traveling.

Our tank is 20 years old, but according to web sites now selling drinking water tanks, the plastic is polyethylene terephthalate aka PET.
To my knowledge, we haven't had any problems to date with bacteria growing. I don't taste plastic. We once had a mouse get in and die. Bad smelling water. It cleared up after a few weeks. Probably drank some of it!
Do you have any information or links? - Barbara Stuart
The above-ground water cistern storage tank shown in our photo (above left) is located in San Miguel de Allende, Mexico and is discussed at [SIZE=-1]PASSIVE SOLAR HOME, LOW COST[/SIZE].

Answer:
As Ms. Stuart pointed out, some water storage tanks are made of plastic polyethylene terephthalate aka PET. Polyethylene Terephthalate (PET, PETE or polyester) is commonly used for carbonated beverage and water bottles.
Some water storage tanks have also been constructed of this material.
PET - Polyethylene terephthalate (PETE, PETP, PET-P) is a thermoplastic polymer polyester plastic resin. plastic water tanks may be a health risk to consumers: Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research on this topic. Proposed mechanisms include leaching of phthalates as well as leaching of antimony. Other authors have published evidence indicating that it is quite unlikely that PET yields endocrine disruptors. - Web search 6/27/2010 Wikipedia. PET

Sorting Through the Confusion of Opinions vs. Studies About Plastic Container Materials, Names, Hazards

Researching the health hazards of plastic containers and asking which plastics are safe can give conflicting and confusing results.
Some sources such as the "green" website Care2.com assert that PET or PETE polyethylene terephthalate and HDPE high density polyethylene plastic containers are "GOOD: Not known to leach any chemicals that are suspected of causing cancer or disrupting hormones.".
These same sources may tag LDPE, PP, PS as "OK", and tagging PVC or V and PS as "BAD - PVC - According to the National Institutes of Health, di-2-ethylhexyl phthalate (DEHP), commonly found in PVC, is a suspected human carcinogen., and BAD PS - According to the National Institutes of Health, di-2-ethylhexyl phthalate (DEHP), commonly found in PVC, is a suspected human carcinogen." - Web search 06/30/2010 care2.com.
There is also confusion about "polyethylene plastic" bottles and tanks. Don't confuse HDPE plastic (high density polyethylene) with PET - Polyethylene terephthalate (PETE, PETP, PET-P) - see What Plastic Was Used to Make My Water Tank (or water bottle)?

Looking at more expert researchers commenting on PET plastic containers:

But recently researchers have raised serious questions about potential health and environmental concerns for PET or PETE plastics. At Reviewers & References see Sax L 2010, López-Carrillo L, et als 2010, Koike E, 2010, for examples.
In April 2010 Environmental Health Perspectives, a peer-reviewed open access journal published by the National Institute of Environmental Health Sciences, Sax reported that

Polyethylene terephthalate (PET) is widely used to make clear plastic bottles for bottled water and containers for other beverages, condiments, and cosmetic products. There is concern that estrogenic chemicals such as phthalates may leach into the contents from bottles made from PET, although PET is not a phthalate derivative. Sax (p. 445) describes several studies suggesting that water from PET bottles can have estrogenic activity in some bioassays and that phthalates might leach from PET bottles.
The author notes the difficulties in evaluating these studies, especially in cases where there may have been prior contamination of the water or the containers with estrogenic agents or phthalates. Sax suggests that the phthalate content of PET bottles, if present, might vary as a function of the acidity of the product and the temperature and duration of storage. Sax also makes the observation that other nonphthalate chemicals such as antimony, which is used as a catalyst in the polycondensation of PET, might also contribute to the endocrine-disrupting activity of products stored in PET containers. The widespread use of PET plastic for a variety of applications suggests that additional research is needed.
The contents of the PET bottle, and the temperature at which it is stored, both appear to influence the rate and magnitude of leaching. Endocrine disruptors other than phthalates, specifically antimony, may also contribute to the endocrine-disrupting effect of water from PET containers.
Conclusions: More research is needed in order to clarify the mechanisms whereby beverages and condiments in PET containers may be contaminated by endocrine-disrupting chemicals.
​

If your water storage tank is made from Polyethylene terephthalate (PET), and is exposed to high temperatures such as exposure to direct sun and/or in a hot climate, the health risk may be increased. At References, below, we include citations of several recent articles discussing health risks from Phthalates and PET containers.

Find Your Water Tank Plastic Type from the Manufacturer's Literature, Website, or Sales Support

Watch out: some plastic water storage tank distributors advertise that their tanks comply with some health and sanitation laws while omitting any comment about the type of plastic or possible PET concerns (see below). For example we found plastic water tanks advertised as

Specified IW series water tanks manufactured at Chem-Tainer's Compton, California factory are IAPMO certified to comply with the California Lead Plumbing Law and NSF/ ANSI 61- ANNEX G. This law states that any devices or components sold in the state of California that come in contact with potable water must comply with this law.
​

But it's easy to check the manufacturer's website or to ask the plastic water tank manufacturer for specifics of the plastics used. For example, Chem-Tainer Industries, a producer of a very wide range of plastic storage tanks indicates that

Chem-Tainer's fresh water tanks are an effective, economical way to store potable (drinking) water for Residential and Commercial applications. Our polyethylene resin complies with U.S. Food and Drug Administration regulation 21CFR 177.1520 (1) 3.1 and 3.2 for storage of potable water. These tanks are designed for water use only.
​

BPA - Bisphenol-A - containing Plastics: A Quick Summary on Endocrine Disruptors



Details about BPA plastics in food and liquid containers are found at Bisphenol-A, BPA. Excerpts are below.
According to the New York Times (7 Sept 2010)

Concerns about BPA stem from studies in lab animals and cell cultures showing that it can mimic the hormone estrogen. It is considered an "endocrine disruptor," a term applied to chemicals that can act like hormones. But whether it does any harm to people is unclear.
About half a dozen [U.S.] states have banned BPA in children's products ... This year a presidential panel on cancer and the environment said there was a "growing link" between BPA and several diseases, including cancer, and recommended ways to avoid BPA, like storing water in bottles free of it and not microwaving food in plastic containers. Some cancer experts said the report overstated the case against chemicals, but the concerns it raised seem to reflect growing public worries.
​

OPINION: Readers interested in the subtle but powerful effects of hormone mimicking chemicals and endocrine disruptors that appear in the environment, their sources, effects, and risks, should also see Our Stolen Future, Theo Colborn, Dianne Dumanoski, and John Peterson Myers and discussed at Reviewers below. Quoting from Amazon:
See details about BPA concerns in plastics used to contain food products, at Bisphenol-A, BPA.
Difficulty of Research About Chemical Contaminants is discussed at [SIZE=-1]CHEMICAL CONTAMINANTS in WATER[/SIZE].

 

Small scale water tower

How To Build A Double Duty Water Tower


A Tower And A Shower

Setting up a water tower became the first major project on our Arizona homestead unless one counts the septic tank installation. While that (the septic) was being handled by a licensed contractor as required by Cochise County regulations, I got going on the structure that would eventually support a 500 gallon water storage tank.
Why 500 gallons? Why not 750 gallons or possibly 1,000 gallons? After all, even a small family can go through a lot of water in a week when you consider bathing, toilet flushing, laundry, etc. The answer was simplicity itself: Cost. A 500 gallon tank could be purchased online and delivered right to our door for under $400, and the dimensions of the one we actually purchased (64 inches in diameter, 42 inches high) also just "felt" right.
Since the camp trailer's bathtub is being used to hold the food and water dishes for our household cats and the shower head itself has been gone for years, I decided to build the water tower with side walls that would serve to both (a) brace the support posts holding up the water tank and (b) provide a place to take showers.
You might say it's a water shed (Snicker! Snicker!).
Step One involved planting four posts. These are 4" x 6" treated timbers, each 12 feet long. It would have made me happier to use 6" x 6" beams, but the local stores only stock that size in stubby 8 foot lengths. Boo. Hiss. No way was I going to spend the money to special order.
The posts are set roughly six feet apart in a square pattern with three feet buried in the Earth and nine feet above ground.


See all 20 photos


The four treated posts in position. The horizontal 2" x 4" boards are temporary, simply tacked in place to stablize the posts momentarily.


The Major Support Planks

Next came the planks which would do the most strenuous job of all, i.e. supporting a set of deck joists. Now, I know the definition of a deck joist, but what the dickens do you call the cross joist underneath the deck joist? (I figure a savvy reader will eventually tell me and thus save me the work of looking it up for myself.) Okay, so the definition may be elusive, but the job these planks have to do is quite clear. Every bit of water weight will depend on their strength, so they needed to be as burly as possible.
In the end, a pair of 2" x 12" planks looked like they would do the job nicely, especially after being attached to the posts with four strong 3/8" bolts that ran completely through both plank and post and were cinched down with fender washers as well as lock washers. That meant drilling holes for the bolts, and that meant buying a drill bit long enough to do the job.
Note: This entire project was done without the use of so much as a carpenter's square. I have one...but it's hiding. A level was used constantly, though.
These planks were "green" lumber and therefore extremely heavy. When the first one (south side) went up, it was no problem: Just "pick a spot", tack one end in place, and use the level to make sure the other end hits the right spot. But the second plank (north side) had to match the height of the other one, which was a problem. Since I work alone from necessity and by preference, I couldn't just holler at my assistant to hold up one end. The solution: Leave one end resting on a lower "leveling" board while tacking the other end as close to the upper "leveling" board as the angle would allow. Then lift the lower end, "eyeball" the position, and tack that. Back and forth, until the plank was finally in the proper position as confirmed by use of the actual level.
I don't ever build a project without the project itself changing my plans frequently along the way. This is not a drawback; it's just the way I work. Two adjustments popped up by the time the heavy planks were in place and ready to be bolted.
Adjustment #1: Sixteen 3/8" bolts had been purchased at Home Depot to secure the planks to the posts, figured at four bolts at each end of each plank. Just to be on the safe side, I'd paid for eighteen--two extra, right?
Wrong. Of the eighteen bolts, eight were the wrong size. Careless shopping, cowboy.
Okay, so put in what we had, get the rest later. That amounted to two of the posts getting two bolts each and two of them getting three bolts each. Plenty strong enough for the moment.
Adjusment #2: There were two other planks, 2" x 8" size, treated version, that were literally just lying around. I decided to just slap them up there under the 2" x 12" boards as extra reinforcement--but rather than go shop for more bolts, why not just nail them in place? After all, another leftover happened to be a number of 16d ring shank spikes. Five of those hammered into each end, and we were good to go.
The treated boards were longer than the others, but for now they'll stay that way. Who knows? They may inspire a future addition to the shower shed which will house a washing machine or garden hoses or...you never know.
One thing I did know: For this particular project, the hard part was done. Or so I thought....



A level was used constantly. This board is another "temporary" item, set in place only to make sure the support planks at opposite sides of the tower were installed at the same height.

The south side plank in position.

One end of the heavy plank (north side, second to install) tacked up "close" to proper height.

Both main support planks in place and the leveling board(s) removed.

"Extra" treated 2" x 8" reinforcement plank in position for nailing, held in place briefly by 2" x 4" braces.


Adding The Deck Joists

The next two boards were pure fun. All I had to do was slap them up on top, running across from plank to plank, and nail them firmly to the posts. How easy is that? True, the tape measure had to be used in order to be sure the ends stuck out evenly, and then a 2" x 4" board was tacked across those ends. Why? Because by "bumping" all of the in-between joists lightly against that board, the row would come out even with very little effort.
Then came a tricky little maneuver. Remember my saying that this entire structure was built without the use of so much as a carpenter's square? All true. But when you do that, you can't complain when the distance between posts isn't exactly the same at the two ends. And they weren't. Checking the distance and using a little simple division told me that in order to make the finished set of deck joists look evenly spaced to the naked eye--which is rather easily fooled, by the way--the distance between boards at the north end needed to be 5 1/4 "...but the distance at the south end needed to be 5 5/16 ". In order to make that happen, I cut two spacer sticks, one for each end, and stuck them in my hip pockets between uses.
Then, when nailing the joists in place with slick litttle gizmos called "hurricane hangers", I'd check the spacing with the appropriate stick...and repeat the process, over and over again.
By the time all eleven joists were fixed in position, the support deck was really starting to look like something.



The two outside deck joists nailed firmly in place and the keep-'em-even board tacked across one end.

The handy dandy spacing sticks.

All eleven deck joists in place, view from the west.

Looking up!

From the topside....

...and one last looksee.


The Deck Floor

The deck floor itself was to be a solid row of 2" x 4" boards, each snugged against its neighbor as closely as possible without laminating the things. Despite the fact that unavoidable delays had left the green lumber out in the sun to warp for a while, this particular task promised to be the most enjoyable few hours of the entire project. There wasn't much thinking or adjusting to do--just hammer in a few hundred 10d nails so that every deck board was firmly fastened to every joist.
Naturally, few things ever go quite the way one imagines in advance. As it happened, the last few dozen nails were actually hammered into place by flashlight. Add to that the discovery that 242 nails pounded with a 16 ounce hammer (rather than the 24 ounce framing hammer and/or nail gun most union carpenters would use)...that many nails were enough to make me notice an almost-strain in the right elbow tendon.
So? It was still a great day, and the basic tower was all set. Not ready for the weight of 500 gallons of water, of course. The structure still needed a few additions to possess sufficient rigidity for my taste. But enough to celebrate by moonlight with an extra cup of coffee.



The deck floor is good to go, finished last night afte dark.

View from the east.

Leaving the outer ends of the deck joists exposed was deliberate.

Such a pretty job; too bad it has to be painted!


Double Duty Reinforcement

Whether made of wood or (more commonly around here) metal, most water tank support towers display plenty of bracing. These braces are usually placed diagonally between adjacent corners. It made me grin from ear to ear to realize something: By using super-cheap strand board, available from Home Depot in 4' x 8' sheets 15/32" thick at around $7 per, I could provide awesome bracing strength while at the same time producing a solid wall which would provide absolute privacy...and serve as a "shower shed".
Note of amused disgust: Of course those boards went on sale after I'd bought all I needed for this project--yesterday they were down to $6.50! Happens every time.....
Once the strand board sheets were installed, the improvement in rigidity was obvious, even dramatic. Prior to that, you could stand on the deck, "wiggle" your feet, and make the whole thing sway enough to definitely feel it...north-south you could, that is. East-west, no: That direction involves both the larger post dimensions and the automatic bracing provided by those big planks. Now you could stand your basic 500 pound gorilla up there, wave bananas at him till he danced, and the thing wouldn't so much as wiggle.
On the other hand, it was only at the last minute that I decided to add interior stud walls behind the strand boards. Yup, it's usually done the other way around. Build your stud walls first, then add the sheathing. Like my late father used to say,
"Kid, you do everything bassackward."
Yeah, Paw, but I still Get 'R' Done.
On three sides, the walls are six feet exactly, top to bottom. On the north side, the bottom two feet are missing. That's still plenty of rigidity--that side is one of those that didn't tend to wiggle anyway, even before the boards were put up. It also leaves a gap at the bottom where my wife and I can scoot under the wall to go take a shower. Uh-hunh. A "door" that doesn't look like a door.
On the inside, a swing-up door will be added--that has yet to be built--which will drop down for privacy only when one of us is in there getting all clean & stuff.
About the time this much had been accomplished, the water tank arrived via motor freight. That the driver was able to find our off grid location was a true testament to my superior direction-giving abilities, but my salesmanship must have been rusty: I couldn't persuade the trucker dude to hang out long enough to help me hoist the tank to the top of the platform.
Sigh.



The first round of wall boards (doing double duty as braces) are installed.

A section of interior stud wall.

The completed water tower just waiting for the water tank to climb on up there.


Finishing Touches

Details on how to lift a water tank to a water tower are provided in a separate hub, but the point is that the tank is now up there where it belongs. There are still a few details to wrap things up, namely a couple of stud walls, installing more permanent tiedowns, a lot of paint (the bare boards in the photos won't remain unclad much longer), the vertically swinging door, and a platform on the dirt inside on which to stand while showering.
One key detail which escaped the photos: On top of the deck, the base of the tank is "enclosed" with eight pieces of 2" x 4" boards, a rough octagon, all nailed firmly to the deck. In other words, the tank can't slide even a millimeter in any direction; it would have to literally "jump" out of its enclosure.
Bottom line? The tough stuff is accomplished. The incoming and outgoing water lines are both hooked up, an initial leak in the outgoing line has been successfully repaired, and--hooray!--the camp trailer now has running water. Or trickling water, at least; Pam has already pointed out that a few vertical feet of pressure don't amount to a lot in a gravity feed situation.
For me, however, having even slowly running water to use when washing my hands at the kitchen sink is a true luxury.



The water tower, plumbed and in operation.

 

<center>[SIZE=+4]Water Towers[/SIZE]
<hr width="100%" size="1">[SIZE=+3]Open Water Towers[/SIZE]



[SIZE=+3]Open Water Towers[/SIZE]
[SIZE=+1]1 Story Open Water Tower[/SIZE]
[SIZE=+1]2 Story Open Water Tower[/SIZE]
[SIZE=+1]3 Story Open Water Tower[/SIZE]
[SIZE=+1]4 Story Open Water Tower[/SIZE]
</center> The Open Frame Water Towers vary between 10' to 20' at the base and 12' to 40 ft' in height. The main towers are built of either 6x6's or 8x's for posts and braces. Upper platform is built with 6x joists and 2x decking. If you just want an observation tower, you don't need a tank, just a handrail. The tower can, however, be designed to hold water tanks up to 2,000 gal. If you would like to Enclose the Tower, you can add intermediate floors and create usable spaces. These towers make a handy solution to storing water for residential or agricultural use. They can provide gravity flow water when needed and the rooms can be used for any number of possible uses. These towers can also be adapted to serve as a Lookout Tower.
The Water Towers are designed to the new 2008 International Building Code for 80 mph winds and seismic zone 4 requirements for California, the most stringent. All plans are signed by a licensed California Structural Engineer or Architect.
<center>

</center>
<hr width="100%" size="1"> <center>[FONT=Arial,Helvetica][SIZE=-1]Last Update 1/23/09[/SIZE][/FONT]
</center>

 

<center>[SIZE=+4]Water Towers[/SIZE]
<hr width="100%" size="1">[SIZE=+3]1 Story Open Water Towers[/SIZE]

[SIZE=+1]1 Story Open Water Tower[/SIZE]

[SIZE=+1]1 Story Open Water Tower - Smaller Platform[/SIZE]

[SIZE=+1]1 Story Straight Leg Towers[/SIZE]</center> [SIZE=+2]1 Story Sloped V Braced Open Tower:[/SIZE]
<small>[SIZE=+1]<small>No. of stories for Tower: 1</small>[/SIZE]
[SIZE=+1]<small>Tower Base Dimension: Approximately 12' sq.</small>[/SIZE]
[SIZE=+1]<small>Tower Height: Approximately 10'</small>[/SIZE]
[SIZE=+1]<small>Platform Height: Approximately 12'</small>[/SIZE]
[SIZE=+1]<small>Tank Size: Up to 2000 gal.(special designs available on request)</small>[/SIZE]
[SIZE=+1]<small>Platform Size: 14' sq.</small>[/SIZE]
[SIZE=+1]<small>Member Sizes: 6x6's for posts & diagonals, 6x Platform Joists, 2x Decking</small>[/SIZE]
[SIZE=+1]<small>Wind Load: 80 mph (will adjust for your local area)</small>[/SIZE]
[SIZE=+1]<small>Seismic Load: Zone 4 regulations (will adjust for your local area)</small>[/SIZE]
[SIZE=+1]<small>Snow Load: 0 psf (will adjust for your local area)</small>[/SIZE]
[SIZE=+1]<small>Cost: VariesseePrices for Tower Plans</small>[/SIZE]
</small><small>[SIZE=+1]<small>Includes: Basic Open Tower and Platform.</small>[/SIZE]</small>
<small>[SIZE=+1]<small>Additional Costs:</small>[/SIZE] </small>Adjust for Stairs, Ground Freeze, Higher Wind, Seismic or Snow Loads. Printing and Shipping.<small>
[SIZE=+1]<small>Changes and Modifications to plans: see Custom Designed Towers</small>[/SIZE]</small>
<small>[SIZE=+2]<small>Before You Buy:</small>[/SIZE]
[SIZE=+1]<small>Check with your local Building Department Jurisdiction to verify acceptance of the plans. Verify whether a permit is needed and whether a local engineer or architect needs to sign them. Verify what the local snow and wind loads are for your area.</small>[/SIZE]
[SIZE=+1]<small>Check with your local Planning Department. There are often, use, height, appearance, area, material or property set back limits that need to be addressed.</small>[/SIZE]
[SIZE=+1]<small>Verify type of soil before building. Designs are based on having a suitable firm soil material to build the foundation. </small>[/SIZE]</small><small>[SIZE=+1]<small>See Building Code & Geologic Notes.</small>[/SIZE]</small>
[SIZE=+1]Order Plans[/SIZE]

 

<center>[SIZE=+4]Water Towers[/SIZE]
<hr width="100%" size="1">
[SIZE=+3]2 Story Water Tower[/SIZE]
[SIZE=+1]2 Story Open Water Tower[/SIZE]</center> [SIZE=+2]2 Story Sloped V Braced Open Tower:[/SIZE]
<small>[SIZE=+1]<small>No. of stories for Tower: 2</small>[/SIZE]
[SIZE=+1]<small>Tower Base Dimension: Approximately 14' sq.</small>[/SIZE]
[SIZE=+1]<small>Tower Height: Approximately 18'</small>[/SIZE]
[SIZE=+1]<small>Platform Height: Approximately 20'</small>[/SIZE]
[SIZE=+1]<small>Tank Size: Up to 2000 gal.(special designs available on request)</small>[/SIZE]
[SIZE=+1]<small>Platform Size: 14' sq.</small>[/SIZE]
[SIZE=+1]<small>Member Sizes: 6x6's for posts & diagonals, 6x Platform Joists, 2x Decking</small>[/SIZE]
[SIZE=+1]<small>Wind Load: 80 mph (will adjust for your local area)</small>[/SIZE]
[SIZE=+1]<small>Seismic Load: Zone 4 regulations (will adjust for your local area)</small>[/SIZE]
[SIZE=+1]<small>Snow Load: 0 psf (will adjust for your local area)</small>[/SIZE]
[SIZE=+1]<small>Cost: VariesseePrices for Tower Plans</small>[/SIZE]
</small><small>[SIZE=+1]<small>Includes: Basic Open Tower and Platform</small>[/SIZE]</small>
<small>[SIZE=+1]<small>Additional Costs:</small>[/SIZE] </small>Adjust for Stairs, Ground Freeze, Higher Wind, Seismic or Snow Loads. Printing and Shipping.<small>
[SIZE=+1]<small>Changes and Modifications to plans: see Custom Designed Towers</small>[/SIZE]</small>
<small>[SIZE=+2]<small>Before You Buy:</small>[/SIZE]
[SIZE=+1]<small>Check with your local Building Department Jurisdiction to verify acceptance of the plans. Verify whether a permit is needed and whether a local engineer or architect needs to sign them. Verify what the local snow and wind loads are for your area.</small>[/SIZE]
[SIZE=+1]<small>Check with your local Planning Department. There are often, use, height, appearance, area, material or property set back limits that need to be addressed.</small>[/SIZE]
[SIZE=+1]<small>Verify type of soil before building. Designs are based on having a suitable firm soil material to build the foundation. </small>[/SIZE]</small><small>[SIZE=+1]<small>See Building Code & Geologic Notes.</small>[/SIZE]</small>
[SIZE=+1]Order Plans
[/SIZE]
<center> [SIZE=+2]Samples[/SIZE]
</center> <center> <table border="0"> <tbody> <tr> <td></td> <td></td> <td style="vertical-align: top;">
</td> </tr> </tbody> </table> </center> <center>Click on the Photo for a Larger View</center> <hr width="100%" size="1">

[FONT=Arial,Helvetica][SIZE=-1]Last Update 5/24/09[/SIZE][/FONT]​

 

<table width="100%" bgcolor="#f8f5e9" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td valign="top" width="680" align="left" bgcolor="#f8f5e9"> <table width="100%" border="0" cellpadding="8" cellspacing="0" height="100%"><tbody><tr><td class="content_style" valign="top">The Biosand Filter

</td> </tr> </tbody></table> </td> <td width="120" align="left"></td> </tr> </tbody></table> <table width="100%" bgcolor="#efe4b8" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td valign="top">
<table style="margin-bottom: 1px;" width="200" border="0" cellpadding="0" cellspacing="0"><tbody><tr> <td class="lnav" valign="top" align="left">Application
Rapid vs slow filtration
Intermittent vs continuous
Filtration process
Filter media
Effect on water quality
Water quality testing
Health impact
Sand filter types
Start a project
Operation & Maintenance
Further research
</td> </tr> </tbody></table> </td> <td style="padding: 0px 0px 0px 10px;" valign="top">
<table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody><tr> <td valign="top" width="5"></td> <td style="padding: 0px 4px 8px 10px;" valign="top" width="90%"> <table class="content_style" width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody><tr> <td> The effectiveness of slow sand filtration for water treatment has been very well documented.
"No other single process can effect such an improvement in the physical, chemical and bacteriological quality of surface waters." (ref.01)
By clicking on the links on the left, you will find a wealth of information on sand filtration.
Firstly, there is a review of the differences between rapid sand filtration and slow sand filtration, since the processes involved and applications are inherently different. Also the differences between continually-operated and intermittently-operated sand filters are explained, as both systems are commonly used in humanitarian programmes.
In addition, we have drawn together detailed information on the processes at work in slow sand filtration, including an in-depth look at flow rates and the physical/mechanical and biological processes involved. Alongside this, there is an explanation of different kinds of filter media that can be used in filters, including an explanation of what is meant by effective size and uniformity coefficient, as well as why media size is important in sand filtration. In here you will find out how to do a sieve analysis to determine what kind of sand you have in your area. The effect of sand filters on water quality is reviewed, which documents much of the research done to date both on how continually and intermittently-operated sand filtration systems affect biological, chemical and physical parameters. Alongside this is a section of how to carry out water quality testing, particularly microbiological quality.
Another section explains the various types of sand filters commonly used in humanitarian projects, including how to start a successful filter project. In here you will find practical technical information that will enable you to build your own mould and concrete filters.
Lastly, a section deals with additional research that is needed to fill the knowledge gaps that exist.
Several principles of sand filtration need to be understood, and these are briefly described below. More detailed information is available on this site - just click the links to the relevant pages on the left hand side of of this page.

• Definitions of rapid and slow sand filtration;
• Principles of slow sand filtration;
• Continually-operated slow sand filtration;
• Intermittently-operated slow sand filtration;
• Further reading & Links.

<hr> Definitions of rapid and slow sand filtration
Rapid sand filtration is mainly used in combination with other water purification methods. The main distinction from slow sand filtration is the fact that biological filtration is not part of the purification process in rapid filtration. Rapid filtration is used widely to remove impurities and remnants of flocculants in most municipal water treatment plants. As a single process, it is not as effective as slow sand filtration in production of drinking water. In general, slow sand filters have filtration rates of up to 0.4 m/hour, as opposed to rapid sand filters which can see filtration rates of up to 21 m/hour.
As its name suggests water in rapid filters passes quickly through the filter beds. Often, it has been chemically pre-treated, so that little biological activity is present. Physical straining is the most important mechanism present in rapid filters. Particles that are larger than the pore spaces between the sand grains are trapped - smaller solids however can pass through the filter. Rapid sand filtration removes particles over a substantial depth within the sand bed.
In contrast, slow sand filters can remove particles that are smaller than the spaces between sand grains. Slow sand filters contain very fine sand and usually function without chemical pre-treatment, such as chlorination or flocculation. The low filtration rate causes long detention times of the water above the sand and within the sand bed. This allows substantial biological activity. Slow sand filtration removes particles mainly at the surface of the sand bed.
Where maintenance is concerned, rapid sand filters are usually cleaned on a daily basis using backwashing, whenever terminal head loss is reached. To clean the filter, the flow of water is reversed through the filter bed at a high rate so that the sand bed fluidizes. This flushes out all materials trapped between the sand. In comparison, to backwash a slow sand filter bed in the same way would destroy the bio-film and disrupt the intricate inter-relationships of sand and micro-biological life. The flow rate in slow sand filters is therefore usually restored by scraping and removing the top layer of sand, which is where most clogging occurs. Hence, large quantities of backwash water are not required.
Rapid sand filters are suitable for large urban centers where land scarcity is an issue, whereas slow sand filters tend to be more suitable for areas where land is more available, since they need a much larger surface area to treat the same amount of water. Slow sand filtration is simpler to operate than rapid filtration, as frequent backwashing is not required and pumps are not always necessary.
Principles of slow sand filtration
A slow sand filter contains biological activity and is therefore often referred to as a bio-sand filter. As micro-organisms such as bacteria, viruses and parasites travel through the sand, they collide with and adsorb onto sand particles. The organisms and particles collect in the greatest density in the top layers of the sand, gradually forming a biological zone. The biological zone is not really a distinct and cohesive layer, but rather a dense population that gradually develops within the top layer of the sand. The population of micro-organisms is part of an active food chain that consumes pathogens (disease-causing organisms) as they are trapped in and on the sand surface. The uppermost 1-3cm of this biological zone is sometimes referred to as 'schmutzdecke' or 'filter cake'. Which is defined as a layer of particles deposited on top of the filter bed or biological growth on top of the filter bed. Slow sand filters are usually cleaned by scraping of the bio-film and/or the top sand layer.
Continually-operated slow sand filtration
In order to be effective, most literature insists that a constant flow of water passing through a slow sand filter is essential. This flow provides oxygen and food to the organisms that make up the 'schmutzdecke' and biological zone living within the top part of the sand, which are responsible for much of the removal of disease-causing organisms. Under stagnant conditions, the biological can start to die - sometimes within several hours.
Click here to read more on biological activity in slow sand filters
Intermittently-operated slow sand filtration
Until recently, it was considered impractical to operate a slow sand filter intermittently, due to the need for a continuous supply of food and oxygen. However, Dr. Manz of the University of Calgary re-designed the traditional sand filter, making it suitable for intermittent use at a household level. This adaptation, brilliant in simplicity, consists of raising the under drain pipe back up to between 1 and 8 cm above the sand level, ensuring a foolproof method for maintaining the water level just above the sand. Manz proved that, even when water is not continually added to the filter, oxygen can still permeate into the water to reach the organisms living in the sand by diffusion accross this shallow layer of standing water.
Intermittently-operated slow sand filters can be small units that easily supply enough clean water for a family. Therefore, they are particularly suited for use in low-income countries, where the majority of people rely on untreated, contaminated surface water. Find out in detail how intermittently-operated slow sand filters work.
Further reading:
Haarhoff, J.; Cleasby, J.L. (1991). Biological and physical mechanisms in slow sand filtration. In: Slow Sand Filtration. Logsdon, G.S. (ed.). pp. 19-68. American Society of Civil Engineers, New York, USA.
Links:
The Centre for Affordable Water Supply, CAWST, is one of the main champions of household bio-sand filtration. They offer trainings and have developed quality promotional materials. Their website offers a wealth of information on the bio-sand filter.


<hr> References: (jump back) ref.01: Huisman, L.; Wood, W.E., 1974, Slow Sand Filtration, World Health Organisation, Geneva.
</td></tr></tbody></table></td></tr></tbody></table></td></tr></tbody></table>

 

Well Chlorination Procedure: when and how to shock a drinking water well
[SIZE=-1]InspectAPedia^® - ShareThis [/SIZE]

• How to shock the well - well shocking procedure
• When to shock or chlorinate a drinking water well
• What is the procedure to shock or chlorinate a well?
• How much bleach or hypochlorite do you use to shock a well?
• When should well water be re-tested after shocking the well?
• Well shocking details for water filters
• Well shocking details for water softeners
• Chlorinating water - details for water heater tanks
• How quickly should the bleach smell show up at a faucet when I shock the well?

This article explains how to shock a well, when, why, and exactly how to chlorinate a drinking water well. This is a description of the well shocking procedure using household bleach to sterilize well water and water equipment. The purpose of shock disinfection of a well system is to destroy bacterial contamination present in the well system at the time of disinfection and is not intended to kill bacteria that might be introduced at a later time.
[SIZE=-2]Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.[/SIZE] <ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="google_ads_frame4_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins>
<ins style="display: inline-table; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"><ins id="google_ads_frame5_anchor" style="display: block; border: medium none; height: 90px; margin: 0pt; padding: 0pt; position: relative; visibility: visible; width: 728px;"></ins></ins> Page top sketch of deep and shallow wells courtesy of Carson Dunlop.
This website explains many common water contamination tests for bacteria and other contaminants in water samples. We describe what to do about contaminated water, listing common corrective measures when water test results are unsatisfactory. We include water testing and water correction measures warnings for home owners and especially for home buyers when certain conditions are encountered, with advice about what to do when these circumstances are encountered. Various treatment methods for contaminated water are reviewed and the pros and cons of each are discussed. Readers concerned with the effects of well shocking on septic systems should see [SIZE=-1]CHLORINE IN SEPTIC WASTEWATER[/SIZE].
© Copyright 2011 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.
When and How to Shock or Chlorinate a Well - Procedure for Shocking a Well to (temporarily or maybe longer) "Correct" Bacterial Contamination in Well Water

This information is from the Dutchess County Health Department's environmental laboratory but you'll find that it is consistent with the well shocking or well chlorination procedures recommended by most health authorities.
The purpose of shock disinfection of a well system is to destroy bacterial contamination present in the well system at the time of disinfection and is not intended to kill bacteria that might be introduced at a later time.
Our photo shows an owner who has lifted the loose, poorly-sealed well piping and cap right off of the steel well casing. This well needed repairs and it needed to be sterilized using the well chlorination procedure we discuss here.
Therefore it is vital that the well be constructed so that no new contamination may enter the well following completion of the shock disinfection. In order to achieve a satisfactory disinfection of the system, the bacteria must be brought in contact with a chlorine solution of sufficient strength and remain in contact with that solution for a sufficient time to achieve a complete kill of all bacteria and other microorganisms.
Chlorine in Wells - Safety Warnings

When working with chlorine, people should be in a well-ventilated place. The powder or strong liquid should not come in contact with skin or clothing. Solutions are best handled in wood or crockery containers because metals are corroded by strong chlorine solutions.
Details of the Well Chlorination Procedure - Exactly How to Shock a Well, Where to Put Chlorine, How Much Chlorine to Use to Shock the Well

<table width="100%" cellpadding="0" cellspacing="0"><tbody><tr><td valign="TOP" width="70%"> If drinking water has been tested and has not passed standards for safe drinking, or any time the building water supply system has been opened for repairs (such as replacing a submersible well pump or a jet pump foot valve), the well should be disinfected following these procedures, and should be re-tested as described below.
Our photo shows a standard modern 6" steel well casing - it's easy to spot at a property.
If you don't know where the well is located you'll have to find it before this well chlorination procedure can be best performed. See [SIZE=-1]WELLS CISTERNS & SPRINGS[/SIZE] for articles that describe different types of water wells, what they look like, where they're found, and their operating characteristics.
It's possible to get chlorine into the well by sending it through the building piping and pump but that step won't sterilize the interior and sides of the well casing - so the procedure below is a better one.
</td></tr></tbody></table>

• Pour Clorox™ Bleach (or an equivalent brand of household bleach) or hypochlorite granules down into the well. Some people use swimming pool chlorine tablets which have the advantage that they sink to and sterilize water at the well bottom, and the disadvantage that it takes longer to flush out the chlorine.
• How much bleach to use when shocking a well: Health department officials can give more precise guidance about the amount of disinfectant needed based on the depth of the well. Common guidelines:
  • Well depth 100' - 3 cups Clorox or 2 oz. of granules.
  • Well depth 200' - 6 cups Clorox or 4 oz. of granules.
  • Well depth 300' - 9 cups Clorox or 6 oz. of granules.
  • Well depth 400' - 12 cups Clorox or 9 oz. of granules.
  • Well depth 500' - 1 gallon Clorox or 12 oz. of granules.
  • NOTE to be accurate in reaching the necessary concentration of chlorine in your well, treat the "depths" listed above as if they were the height of the actual column of water in your well (assuming a standard casing which is 1.5 gallons per foot of height). So if your well is 400 feet deep, but if 100 feet of it is air, your water depth is actually 300 ft.
  More about measuring the actual depth of a well is at [SIZE=-1]DEPTH of a WELL, HOW TO MEASURE[/SIZE].
• Introduce the chlorine solution into the top of the well. Remove the cap at the upper terminal of the well casing and pour the chlorine solution down the inside of the casing. If the well casing terminates through the floor of a pump house, then the casing is required to have a well seal at the upper terminal [i.e. at the top of the casing]. This well seal can be loosened and the chlorine solution introduced into the well at that point. In a large diameter well [such as a public supply company's well], the chlorine solution should be poured or splashed around the wall of the well so that all inside surfaces of the well are brought into contact with the strong chlorine solution.
• Using a garden hose, spray water down into the well pipe to wash the chlorine solution down to the bottom of the well. Ten gallons of water should be enough. [More won't hurt nor risk running the well dry since you're recycling the well water through the plumbing and back to the well.]
• Turn on all cold water household taps until you can smell the Clorox coming out of the faucet farthest from the well.
• Turn off the water and do not use it for 8 to 24 hours. Seal the top of the well. Do not run laundry with this chlorinated water or it may bleach clothing unexpectedly.
• At the end of the standing period, operate the well pump (run the water) water until you can no longer smell the Clorox. Do not run Clorox into the septic system - run water outside through an outside faucet or hose. There should be a hose connection at the at the bottom of the water tank. When you no longer smell chlorine at the hose draining the water tank, close off the drain and open all faucets in the house to flush out house piping for fifteen minutes or until you no longer smell or taste chlorine [whichever is longer].
• Retest the well water after all the Clorox or chlorine is out of the system and the water has been used for 5-7 days (typical health department guideline) or 7-10 days (my suggestion) after the disinfection.
  
  The longer you wait until the retest the more valid will be the results. We elaborate on this point at "When to re-test your well water" below.

Well Chlorination Procedure for Water Filters, Water Softeners, and Water Heaters

Question:
I would like to know when I chlorinate my well should I bypass the water softener and any filter in the line.
Also why does it say to turn on just the cold water? - Jerry Highsmith
Answer: We recommend these added water filter, water softener, and hot water heater details that may be helpful when shocking or chlorinating a well.
Water filters

Take out the water filter cartridge then close up the canister, but do not put it on bypass. Let the chlorinated water run through the canister to sterilize and clean it, then install a new filter after all chlorine-smelling water has been flushed from the system.
Water softeners

Bypass the water softener for the same reason we explain below about water heaters, and with the same exception as below.
Water heaters

Bypass the water heater when chlorinating the well for this reason: if you put chlorine-treated water inside the water heater, because incoming water in the water heater tank keeps mixing with what's already in the tank, it is difficult to flush all of the chlorinated water back out of the water tank without running a very large volume of water through the system.
Watch out: Also heating water that contains a high level of chlorine might produce potentially dangerous chlorine gas coming out of a hot water faucet.
If your water heater piping does not make it easy to bypass the actual water heater while running chlorinated water through both cold and hot water piping, then you might want to just run cold water in the building.
When flushing chlorinated water out of a well, it's fine to run that water through both hot and cold water piping and fixtures if you can bypass your water heater tank itself. That helps sanitize all of the building piping. But if you cannot bypass your water heater, you can have trouble getting all of the chlorinated water out of the water heater tank unless you first run cold water until there is no chlorine or bleach odor, then stop and drain any chlorinated water from the water heater tank.
Exception - When to Chlorinate a Water Softener or Water Heater

You might want to run chlorinated water through a water heater tank or water softener tank if you suspect that those devices have been contaminated, such as by bacteria during area flooding, or in the case of a water heater, by bacteria that can form inside of a hot water tank. In that case, however, it may be easiest to simply drain the heater or softener tank completely, manually, after it has been treated (chlorinated) rather than trying to flush it out by running through the many times its actual water volume that would otherwise be required.
Watch out: be sure your water heater has been turned OFF and has cooled down to at least room temperature before trying to run chlorine through it. Heating water that contains a high level of chlorine might produce potentially dangerous chlorine gas coming out of a hot water faucet.
It won't hurt the water heater or water softener equipment itself for a dilute amount of chlorine in water to remain inside it, (after all this equipment is used in some homes where a chlorine injection system constantly places a small amount of chlorine into the building water supply).
Because chlorine is volatile, eventually it will be dissipated as water is used or left in an open container (for use) in the building. See [SIZE=-1]DRINKING WATER - EMERGENCY PURIFICATION[/SIZE] for details.
Watch out: But leaving too much chlorine in any water system can be dangerous: drinking concentrated chlorinated water could be sickening or even fatal, and less seriously, doing laundry with chlorinated water may bleach clothing by accident.
Questions and Answers About Shocking a Well

Question: How Long Will It Take for Chlorinated Water in a Shocked Well to Reach the House?

In a well 700ft deep - how long until the chlorine smell will be get to the house? - B.S.
Reply: We Must Calculate How Much Water is in the Well and House Water Pipes, the Pump Rate, the Piping Distance:

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a well water problem problem. That said, here is how we figure out how quickly the chlorinated well water should appear in the house:
The answer to your question includes the following factors and the simple calculations we present below.
Provided that you used the proper concentration of bleach or chlorine to get the well water level to contain the proper amount of chlorine (as per the text at [SIZE=-1]WELL CHLORINATION SHOCKING PROCEDURE[/SIZE] or per your local health department), the water will definitely smell like "bleach" or "chlorine" at a faucet as soon as well water has run through the well piping, to the building, through building plumbing, and out the mouth of the faucet.
The real answer to your question depends not on the depth of the well (700 feet in your case) so much as the diameter and length of well piping between the well bottom and the water faucet where you are sniffing. We can presume that the chlorine you poured into the well mixes quickly with the water already in the well (the static head), and that the mixing is further agitated if you washed down the well casing sides with chlorinated water as we advise.
A second factor is the water flow rate of your well pump in gallons per minute. For this calculation we will assume your well pump delivers a conservative 10 gallons per minute of water flow through the system piping when the pump is running. (The true answer is more difficult to calculate because when the pump is not running the water pressure in the piping depends on the water pressure tank and is not constant.)
But we can make make some assumptions based on common values to get in the right ballpark of the time needed for chlorine to show up at the tap of a shocked well.
If for simplicity we assume that all of the piping between the well bottom and the faucet has an average diameter of one inch, then the formula for how much water there is in a foot of pipe is the formula for the volume of a cylinder:
The formula for calculating the volume of a cylinder is:
pi * radius² * height (pi is 3.1416) - [SIZE=-1][We discuss this calculation in more detail at WATER TANK SIZE & VOLUME.][/SIZE]
In the formula above, the radius (which is half of the pipe diameter) should be squared. That is, divide the diameter in half to obtain the radius, and multiply r x r to obtain r².
So for a 12" length (one foot), of one-inch inside diameteer water pipe the volume of water is (keeping all measurements in inches)
3.1416 x (1/2)² x 12 = 18.8 cubic inches of water per foot.
We convert cubic inches to gallons by dividing the cubic inches by 231 (a constant) or we can multiply the cubic inches by 0.004329 (another constant).
18.8 / 231 = 0.81385, so 18.8 cubic inches of water is 0.081385 gallons.
So your theoretical one-inch water pipe contains about 0.08 gallons per linear foot.
You didn't say how far the well is from the house nor how many feet of piping are between the house point of water entry and the faucet, so we'll make some assumptions and you can plug in your own numbers.
Assuming 200 feet distance from well bottom to point of entry of water in the home, and another 50 feet of water piping through the home before water gets to the faucet where you've placed your nose [Watch out: don't get chlorinated water in your eye. ] then
250 feet of pipe contains (0.08 gallons per foot x 150) = 20 gallons.
So we have about 20 gallons of water in the 250 feet. Actually your volume will be less because probably piping in your house is smaller in diameter and probably there is less distance of piping between point of water entry in the house and the faucet.
If your well pump is pumping at 10 gallons per minute, it would take about 20 (gallons) / 10 (gallons per minute) = 2 minutes or less for chlorinated water to show up at the faucet [in a simple and perfect world, which it is not.]
It's a little more complicated.
Some of the incoming water from the well may be diverted into the water pressure tank where it is diluted and in that sense "delayed", and if you are running hot water, some of the incoming water is being diverted and run through your hot water tank where it is significantly diluted.
So if you only ran hot water (the worst case) it could take five minutes or even longer for some diluted but still chlorine-smelling water to appear at the hot water faucet. The cold water faucet output should smell like bleach sooner.
Conclusions:
It's reasonable to expect to smell the chlorinated water at a faucet in a typical one family home within 4 to 10 minutes after shocking the well.
If you run the water for 15 or 20 minutes and you still don't smell the bleach, either you need a more careful look at the distance and size of water piping or a closer look at how accurately you calculated the amount of bleach you poured into the well.
Don't forget that when you are running the chlorinated well-shocked water through the bulding piping and fixtures, you want to run it at every fixture so that everything is being sterilized.
Don't forget to thoroughly flush out the chlorinated water 24 hours later.

 

ummm tag for later reference. Where did all this come from originally? Is there a print copy somewhere?