City water gets into fresh water tank

My Terry Manor has a valve to fill the fresh water tank from the city water. If that valve is leaking or not off all the way it will fill the
fresh water tank.
Happy camping
Dennis

This is a typical water flow setup for the older trailers... The newer trailers may be setup with valves and things to allow your fresh water tank to be filled from the city water connection... My fresh water tank has to be manually filled.



Roy Ken

See you are from TX which has 'hard water'

Calcium and other minerals can build up on the water pump 'internal' check valve which is a one way diaphragm.

Diaphragm gets held open and water from city connection flows back thru pump into fresh water tank.

Shutting off city water supply and using pump and fresh water tank can help flush the pump internals.
After using up whole tank..go back on city water supply.
If still leaking back thru pump you can disassemble pump and clean diaphragms

OR

You can buy/install an in-line check valve in pump 'suction' line and stop the backflow

Shurflo inline check valve

corvettekent wrote:
Yes, you water pump has a one way value that is leaking. Some times you can get lucky buy turning off the city water and turning on the pump so it will flush out the valve, then switch back to city water. If that does not work you can take the valve apart and clean it.

Had to do this last week while camping, our fw tank filled while hooked up to city water. Cleaned out the strainer then turned on the pump and all was well after that.

Yes, you water pump has a one way value that is leaking. Some times you can get lucky buy turning off the city water and turning on the pump so it will flush out the valve, then switch back to city water. If that does not work you can take the valve apart and clean it.

Sounds like a bad check valve, or faulty regulator, you are using a regulator on the city connection, correct? Only places I can think where it could be backfilling is at the water heater, or at the pump. I haven't studied the plumbing system, but if you are on city water, is the pump not needed?

From my experiences with house building, which included plumbing and electrical, if you are going to put pressurized water into a standalone system that uses a pump and holding tank, I would place it after the pump, with a check valve to prevent water from back flushing into the tank. Now that I think about it, the water heater is post pump, so only place I would need a check valve is at the pump, on the outlet side, so that water pressure built up by the pump stays when the pump is off.

Have you checked to see if your system bleeds down when the pump is off and not hooked to City?