It is the plastic dip tube in the cold water side of the heater which has disintegrated. That is why you dont get hot water even though the tank is full of hot water. You can install a new dip tube, but unless you can flush all the old plastic out, it will continue to plug the aerators for a long time.: I have a six year old gas hot water heater. Last week after my wife complained about the limited amount of hot water available for her bath, I drained the heater. Since draining the tank, all of the faucets in the house are contuously clogging with a white substance that resembles small bits of very white sea shell. I called in a plumber who said that he had another customer in the my development using an electric hot water heater that had the same problem. he did not know what was causing the problem. he thought that it might be deposits on the plastic fill tube. does anyone have any suggestions?