When using the water pump with no city water everything works OK with no leaks. When I turn on the city water (with 50 psi regulator) I have a bad leak under the motorhome (inside the floor), but no leaks inside the motorhome. The city water line goes into the chassis and disappears, only the leak comes from within the subfloor or wherever, I can't tell. The leak has to be between the city connector and the check valve going to the main water supply for the motorhome. I need a drawing of the plumbing..... or help form someone who has had the same problem or is familar with the PA 37K motorhome.