[jrockway]

You're at a friends house. They offer you a glass of water. Do you drink it? Do you inspect the filter for biological debris first, and then accept it? If you don't, and you get sick, who compensates you for lost wages? Who compensates your insurance company for the doctor's visit? I think this is, realistically, a complex situation.

Having said that, I'm not sure why a filter is needed. Is your tap water not already filtered enough?