http://www.berkeyfilters.com/

that's a good one, i don't have one...but i'm saving up for one...they're pretty expensive, but you can take lake or pond water, even muddy shitty looking water, and it purifies it...

you can also get filters for it that gets rid of fluoride...and the filters last a very very very long time. it will pay for itself quickly.

any kind that you put on your faucet aren't good...they shove the water through at too high a pressure...

i've tried berkey water, it's really good. so if you have the funds, i'd go with that. made in the usa too!