Unless you live near a reliable source of water such as a stream or lake, you should consider harvesting rain water when the SHTF. As with stream or lake water, you will have to filter it. But if you have a good system, you can acquire all the water you need without ever having to leave home.
BubbleBeet made a short video explaining how he set up a 220 gallon rain barrel system. If a family of four went through 8 gallons of water a day, 220 gallons would still last almost a month. So even if it doesn’t rain for a while, you would still have plenty of water.
You can watch the full video below.
I did this with 2 of those gray Rubbermaid garbage cans like the big ones you see at sporting events. I put a spigot in one and sealed it with aquarium caulk. I then drilled a hole about 2 inches from the top of each barrel and put in a piece of rigid PVC and sealed it with aquarium caulk as well. I cut a piece of screen and anchored it to the barrel under the downspout with bungie cords. I then cut out a hole from the lid of the same barrel and the downspout empties into the barrel though the hole. Once the barrel is full, it overflows into the 2nd barrel. What I ultimately would like to get is one of those 275 gallon tanks in the metal cage. However, I live in the city and I don’t think I would be able to get away with it.
only problem i see is if one sprang a leak they would all loose there water.