Originally Posted by Bob Denman
My RV has a valve at the freshwater tank to cut off the supply of water. Perhaps you have one also?
Ours does too, it cuts off the supply from the FW tank to the FW pump.
On city connection, I noticed my FW tank overflowing out the fill cap, from then on I close that valve when on city connection, and open it when not. Problem I had was solved.