We keep our extra water storage simple. 5 of the 7 gallon Aqua-Tainers. Recently had a generator interconnect installed in our breaker panel which allows us the opportunity to run the well pump with the generator if needed. The wife also wants a "Simple Pump" (Simple Pump Deep Well Hand Pump) installed as a back up, so that's on the list for this summer.
A lot of bigger cities do tax folks for the rain that falls on your property ,, even in a drought . The reason given for the tax is ,,, to be able to afford to contnually repair stormwater drainage systems . And is still charged in outlying areas that have no stormwater drainage systems . Make no doubts about it ,, if you use it ,,, and they find out about it ,,, they'll tax it .
We have a generator that runs the well plus a hand pump. The county I live in wanted to tax property owners for rainfall/storm drainage yet we have no storm drains (another scheme to get money. I live in a small incorporated town most houses are on 2 or more acres sandy soil not much run off. Town told the county no dice
The place I live on has a well, and it measures 179 ppm, and after Brita filtering measures 70 ppm and I'm fine with that. In an emergency I can rig my higher volume filter to serve more people. A 5-gallon bucket, washed sand, and activated charcoal. the sand can be rewashed with calcium hypochlorite (chlorine) and I have enough activated charcoal for 3 changes or more. The level of contamination is not predictable so there is no knowing how long it will last. Wells can become contaminated after earthquake, so never assume your source is invulnerable.
I have several various sized water storage bags...one that can fit in a standard tub, one that fills the bed of my pickup, and one that will cover the floor of one bay in my garage. Of course, weight is of concern when storing water. I also keep some dried chlorine on hand, plus I own a 5 gallon ceramic water bowser with an extra set of spare filters. It can make drinkable water out of virtually any supply. Also have several small 5 gal cans if I needed to transport water or give some to friends. Doesn't take much to prepare to have a water supply as long as you're thinking in advance and don't overtax the budget by needing everything at once.