City water inlet

We did use the pump for the day to use the holding tank water. It may have fixed itself since after that we switched back to city and it wasn't filling the tank.
Thanks everyone!!!!!!

cjlloyd wrote:
No valves or buttons to push. We fill fresh tank on one
Side of the trailer and city hook up on the other

Then you have a 'gravity fill' port to add water to fresh water tank......so if fresh water tank is filling when connected to city water your on-board pump internal check valve is leaking thru.

You can try running/using pump for a day or two to see if any debris/scale holding check valve (diaphragm)open. Some times that is all that is needed to clear check valve.

If that doesn't work......
You can get/install new check valve
You can replace pump....good time to upgrade
You can install a shut-off valve on pump...but you have to open/close valve when swapping between pump/city water
You can install an in-line check valve in pump suction line (easiest and about $10)

No valves or buttons to push. We fill fresh tank on one
Side of the trailer and city hook up on the other

How do you fill your fresh water tank?
By changing valving/switches on a water panel where your cit water connects?
OR
Via a gravity fill port directly to fresh water tank?

Via a gravity port...then your on-board water pump check valve is leaking thru

Via the water panel.....then could be the 'fill' valve OR the pump check valve

Check pump suction side line/strainer for water flow....then you will know which one is leaking thru. Pump check valve or water panel fill valve

if you have a cheapo (oops basic) like mine it is probably the check valve in the water pump.

Two possible causes. (Well 2.2 One (Diverter valve) covered the point 2 is also this valve but you bumped the handle and it's mid-position.

The other suspect is the check valves on the water pump.

Beyond that there are no additional suspects unless you have some fancy things like a "Suck out of a bucket to fill the tank" system in which case those vavles are also suspect,, such are usually after-market add ons. .

I had this happen to me a while back. Real puzzling. Finally figured out that the diverter valve was bad. My city water inlet goes to a 2 way valve. One position for city water, the other to fill the fresh water holding tank.
This may be the same as yours.

Welcome to the Forum.