When the hot water is on, there has been black pieces and white pieces (that resembles Comet) in the water. When only the cold water is on, there seems to be no problem. The only thing I can think that it may be is the problem that was going on with the electric water heater back a few years ago. I think it was called the dipstick. The water heater is around a 1994 model. Could this be the problem or is there something else? Thanks