[rverdlm]

Casey; I don't feel steped on. I was just pointing out that I have not had a valve in any of my RVs and I've never had a problem with back flow into the fresh water tank in over 40 years of RVing.

Bill; There is a check valve between the pump and the water heater, but it has nothing to do with preventing city water from getting to the fresh water storage tank. The check valve is usually screwed into the water heater. The purpose of it is to prevent excess pressure from building up in the water lines when the water heater is turned on.