Originally Posted by OB-One
On my coach the water pump draws water from the fresh water tank. Connecting to city water places the city water and the water pump in parallel. The water source with the highest pressure will provide the water. If I leave my water pump on it will try to pump water from my fresh water tank back into the city water supply because it usually has a higher pressure setting than city water.
The "fix" is to turn off the water pump when connected to city water.
Your check valve is not working correctly. Your water pump should not be pumping water back through the City Water connection.
I am located in a remote wilderness park where the water is supplied through a pump station. The city of Glendale has had many problems with the pump station here so I always make sure my fresh water tank is kept fairly full. Plus I always have my water pump turned on along with the city water supply hooked up. If the parks pump station craps out then my on-board water system takes over and water delivery to my faucets is seamless. When the water pressure is low from the park supply system which happens frequently then my on-board water pump supplements the pressure when needed.
However, my on-board water pump NEVER attempts to back supply water to the parks water distribution system due to a fully operational check valve.
Dr4Film ----- Richard