I believe that I have a slow leak from the cartridge that is in the tub faucet -- it is one faucet for hot and cold. I am going to replace the cartridge, but wanted to know how I can tell if this is the only reason for the slow leak. I can feel slight moisture on the ceiling dry wall below the tub, SO, do I just have to wait and see if the moisture dries up, or is there a way to check and see if the pipe is leaking also??? There is no access to the pipes in the bathroom and there is no leaking at the pipes in the basement.