I was given two cans of water made somewhere in the 50’s that were stored at a ICBM Launch Facility. One was tested for purity, it was OK. The other is a souvenir.
Water itself does not deteriorate with time but it can be contaminated if improperly stored. Proper filtering and disinfecting with chlorine will make most stored water fit to drink.
Imagine the 1800’s and before. Folks traveling cross country stop by a water hole and refill their canteens while their horse is pissing in the same water. I bet they ever even bothered to strain those little plants and animals out of it.
Imagine that hand dug well with the bucket crank and the little roof. And all the birds, snakes, mice etc that fell in and died. Not to mention the birds that perch on the well side and crap down into the well. People still drank it.
And a lot of people got sick and died
My grandad had a couple of wooden water buckets when I was a small kid. There was about fifty cents in silver coins in each bucket. We never dumped the coins out because they were used to stop bacteria from growing in the bottom of the pails. I don’t know how it worked but it did.
I almost never throw out a plastic container. If it’s a 2 liter pop bottle, it gets filled with water. If it’s a gallon or half gallon orange juice grapefruit juice container, it gets rinsed and filled. If its a gallon or 96 or 64 ounce laundry soap container, it gets filled. (hint with the soap containers: don’t rinse them! Now you have good, soapy water if U need it).
My ROT (Rule of thumb) is if it held a food substance when it was real, it’s potable water.
If it held soap or antifreeze or anything non-food, use it as washwater or flushing or whatever.
I must have 200 gallons stored and my aim is to get alot more.