I have a bottom fed cold water supply to my hot water tank in my mobilehome. The cold water pipes (gray plastic) are full of sediment from the bottom of the tank. I can only conclude that this is due to back flow from the hot water tank inlet. Due to the barbed fittings in this type of plumbing I am unable to flush the sediment completely out of the system. Anyone out there heard of this problem before or have a solution for getting the stuff out of my pipes. [email protected]