Try running the hot water for 3-5 minutes and then pouring some plain white vinegar down the drain. It's pretty tough stuff and much more eco-friendly than bleach. Check out this link...

I live in a 2 story townhouse (with a bathroom on the 1st level) and I have to say, I agree with Ebrown, I really love the separation. It's really nice to have your "living spaces" downstairs and...