Depends. Chlorine is a good way to extend the shelf life of munincipal water, expecially when coupled with cool dark storage. We keep a 55 gallon drum in the cold storage room for each person in the family and although we refresh the water annually, it would be safe to assume it could go 5 years (at least). The total amount of water is the reason I use it, not the size of the storage containers - that's a lot of otherwise expensive processes or chemicals to ensure the water is not growing cooties in storage. Bleach is cheap. <br><br>I use iodine tablets otherwise. (Or simply drink the water - it depends on where I am.)<br><br>Chlorine (bleach) will even kill the tough bugs - eventually. The hard bodied stuff like crytosporodium take forever to get knocked out - well, a really long time, anyway. Not practical for immediate consumption, but if one can wait 24 - 48 hours... it's certainly better than no treatment.<br><br>Mostly just another good bit of info to keep tucked away just in case, IMHO.