For Y2K I purchased a 400 gallon plastic tank that was used to ship vinegar. Chlorine is also shipped in these containers. The plastic tank is encased in a metal frame. Empty, they weigh less than 50 pounds. I got mine from a farm store for $125 back then. I plumbed it into a twelve volt water pump such as they have on RVs and marine applications. When activated there is normal water pressure in the house. I used PVC pipe, garden hose, and a couple valves to connect to my house water system.
A couple of years ago, a falling tree took out the power to my well. For several months, until I could aford to replace the power pole. I lived with that system during that time. Normal showers and washing, and toilet flushing would use up the 400 gallons in five days. (I am one person in the house.) I used a generator to power the well pump and fill the tank. It all worked well, with no real serious inconvenience.
I keep the tank covered with a plastic tarp so that the sun will not damage the plastic, or start algae growth with in the tank. The plastic is opaque, which means you can see the level of water in the tank, but direct sun light could cause algae growth.
I think that normally these food containers are used once and disposed of. They are probably not as stout as the plastic containers you are thinking of purchasing, but they should be cheaper, and they seem to hold up well over time.
Survival is nice, but I think having normal pressurized water in the house may help to keep your head straight during bad times.