Hi out there, I am wondering what time limit is on storage of fresh water??I am a bit of a preper..I would like to fill my 90 gallon fresh water tank, just in case I need to bug out. But I am unsure of how long it will stay potable? And can I treat it after it's become non- potable.. To make it once again potable? Any knowledge would be greatly appreciated..thank you in advance for your time and wise dome. Sorry about the mispelled heading...fat finger!