if the water is sterile, and the container impermeable, it will stay sterile until the container is breached-loss of sterility is event-related, not time related. There may be an issue related to leaching of chemicals from the container itself into the water, or through the container if it is water tight, but not impermeable. if the water is not sterile, but is potable at the time of storage, bacteria will multiply if they have something to eat-its the argument against using recycled milk jugs for storage. Maybe the right answer is to save your clorox and plan on treating the water after you open it. Much of the world survives on water that is not as clean as the water in my cellar sump. Chances are that the water you store will be okay, and certainly better than nothing. Most of the diseases that are transmissible by water take longer to kill you than does dehydration, and most of those diseases are self-limiting or treatable.
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Dance like you have never been hurt, work like no one is watching,love like you don't need the money.