In my humble opinion, water is just too important to take chances with. Bleach, Iodine, or water purification tablets will all extend the storage life of water. (I've not tried Imagrunt's idea, but i intend to now.)

They're expensive, but Big Berkey water filters are well worth the investment. I have two, using one for everyday use, and will soon pick up a third since the price has come down somewhat.

The only reason to store water is because, in the early days of a disaster, you will probably be too busy with other survival issues to worry about water. After two or three weeks, you should be prepared to gather and filter your own water.

Onward and upward,
airforce