Fresh water tank filling up

[Adak850]

I have a 2018 Alpine 3401rs and the freshwater tank is filling up when connected to city water. Control valve is set to city water. I think that either the port selector valve is the problem or the check-valve on the pump is open. Anyone had this problem?

[bobbecky]

We had this problem several years ago and discovered it was the check valve built into the pump. At the time, we were not near an RV store, so went into the little town we were near and purchased a check valve that I could install in the PEX line on the pressure side of the pump. It worked like a charm and the pump was just fine except for the failed check valve. I have since replaced the pump for other reasons, but just left the check valve in place. In the photo, the brass check valve is shown above the pump.

[Steveo57]

I just had this happen to me the other day. A campground employee was knocking on the door in the morning telling me that I had water running out of the back of the trailer. It was just coming out of the tank overflow luckily. I just shut off the water and ran the pump for a few seconds and that seemed to fix it. I'll be putting in a check valve on the discharge of the pump as a backup.

I did take the pump apart just to see how it works. Here's a link to the video I made showing the internals of the pump.

https://youtu.be/k7ZprBu_ACs