Fresh water tank filling while on city water

[polarbear]

Spartan

[polarbear]

What would cause this problem and what should I be looking at and doing? Thanks

[Indymule]

The check valve could be stuck open. Are you running the water pump while on city water? this has also been reported as keeping the check valve open and allowing water to backflow into the tank.

[Flybob]

Try this

Disconnect city water
Open a faucet to release pressure in system
Put some water in FW tank if not already there.
Run pump and allow water to run a minute or so.
Shut off water Open faucet to release pressure
Shut off faucet. connect public water
check system.

This causes the backflow valve to open and reseat.

[polarbear]

Thanks. Def gonna try running the water pump this weekend off city water and see what happens