We had a bathroom completely remodeled and now have brown water coming from the tub faucet. Its very brown at first then seems to clear but leaves a brown ring around the tub if its filled. Contractor says its "old pipes" (and is denying responsibility) but we never had the problem before and its not brown ANY WHERE else in the house. Unfortunately we don't have an access panel to the tub faucet. Any ideas? How do I convince the contractor he's responsible?