Leaking Check Valve?

[slabman]

I get periodic instances of water flowing into my fresh water tank
when hooked up to city water. The city water fill valve is set in the
vertical (non-fill) position, suggesting there could be water
intermittently passing through this valve. But now I'm thinking there
must be a check valve in the suction line between the pump and water
tank that could be leaking. Has anyone else had this problem or know
where such a valve is located and how accessible it is?

[RV Wizard]

If the water is not weeping by the "Fill" valve it could be going through the pump. Usually the pump is the "check valve" but might have some debris or weak internals allowing water to make its way through and into the fresh water tank. You might want to try and cap off the line from the tank and the pump to see if this is in fact the problem area. Good luck and keep us posted.

[jamescle]

We had the same problem of the fresh water tank slowly filling when we were hooked up to city water. It turned out to be the fresh water tank fill valve. When it was in the non fill position, it still slowly leaked city water into the freshwater tank. When I replaced the valve, the problem went away. That valve on our coach is a very cheap plastic thing that should be replaced with a more durable one, but I could not find a metal one that could easily be adapted to the panel.

[JimNSandy+4]

This is to Mike, the certified master RV tech who posted a response on Travel Supreme Owners forum.
Mike - we have a post in the Spartan chassis forum regarding 'failed alternator'. Can you read that post and see if you have any suggestions for us? Thanks Jim and Sandy