There's quite a few ways of making water safe to drink. You can filter it all you want, but to sterilize it you should use either bleach or ammonia, or boil it. Most municipal water treatment uses ammonia gas to sterilize water because it costs less than bleach. However you can buy a 50lb bag of calcium hypochlorite at lowes or a pool supply for pretty cheap and it will give you a lot of disinfectant power. Enough for an emergency and then some.
In the less developed countries they drink a lot of tea. There's a social aspect of it, but it's also necessary to boil water to make it safe to drink. If you do plan on storing calcium hypochlorite you're going to have to store it well away from anything you don't want rusting. The gas it gives off will brown any tools you have in the vicinity.
WOW! You just dis'ed all the civilized countries of the world! Gonna be a LOT of UK and related nations mad at you! Not to mention all the Southern USA Good Ol' Boys! You better look for a good hiding place. Nestle and Lipton will be coming for you!