dang! don't buy the bottle water, too expensive! only buy that if you need to keep a bottle of water with you when you go places.
at home, you can use something like a brita water filter. mine looks like a water jug, and you just refill it with tap water when it's almost empty. they aren't too expensive and they filter out most of the harmful stuff as well as the weird smells. personally, i thought the tap water was ok to drink (in santa clara, when i was young). dunno about it now.
also, some supermarkets sell those plastic gallon jugs of purified water. these can be refilled at (purified) water stations for like a quarter each.
anyone have better suggestions? that's all i could think of at the moment.