Water leak

X3 the check valve in your water pump is either got dirt in it or is bad .

Old-Biscuit si right, when my check valve (in the pump) failed, after being connected to city water for several hours, my water tank would be full and water would come out of my fresh water fill.

Pump has an internal check valve....if it is not sealing then water from city water connection can backflow thru pump into fresh water tank and overfill.

Pump check valve kits are cheap and easy to replace.

As I understand it on my rig is that the city water pipe is connected to the output side of the water pump. That city water pipe has a check valve someplace that prevents water from the pump going out the city water connection when it is not used. So your leak would be on the city side of that check valve. That valve may be right at the city water connector.

Can I get at the lines with out removing the tanks , and the water fill does it come apart from the outside or in tank compartment? I know, I sound dumb but trying to remove the fitting is something else

Could be, but more likely leak is in the line that leads from the street connection to the FWT....or anywhere in that line, the water will travel and drop at the lowest point.....

Mine did this ended up replacing
the pump and
Replumbing the city water valve.
This is on a Safari Trek.
Bob