Check valve leak?

[Ericthered]

My using my new to me camper as a seasonal this last month, a coule of times I noticed water trickling out of the fresh water fill. Is this a fault of some check valve ? I assume there is a valve of some sort on the water pump side.
Also, when draining the tank underneath the trailer, it was slow as heck. Is that normal? Perhaps a partially blocked drain valve?

[2slick]

I ended up adding an inline check to keep city water pressure off the pump. Our fresh water tank overflowed, the vent line had a leak in it, and filled the belly of the RV. Coroplast sags bad now.......another project before we hit the road next spring.

[mark5w]

There should be a check valve on the pump itself. If it is defected or you don't have one, then the best solution is what 2Slick said.