Originally Posted by Dennis and Julie
Guess I'm confused every rv we've owned has has a fresh water fill and a city water connection that are seperate and the pump is only used when using water from the tank. So how does your tank fill from city connection?
Both the pump and the city water are (necessarily) connected to the plumbing lines that go to your faucets. If the check-valve in the pump is bad, that common connection will allow water to flow backward thru the pump and into the tank. (And FYI, my RV doesn't have a gravity fill, but fills thru the city water connection after switching a valve.)