Go to a headshop and get some screens, I get a pack of 10 for $1. I read somewhere that most screens in sink faucets are not good for bong screens, don't know how reliable that info is though. My guess is that maybe the screen is a metal that reacts badly when heated by a flame, like aluminum, and then there are the mineral and other deposits left on the screen by so much water flowing through them.

I'm not saying don't do it, just be cautious. Also, once you use the screen on the bong you can't really put it back into the faucet... unless you like your water tasting like reisn.