[Madmax07]

That's very interesting because I did have my underbelly fill with water. This has been an ongoing problem. Last year when it happened I took it to our RV dealer and they found that one of the grey tanks had a crack in it so they replaced it. Before they replaced it I would leave the gray tank valve open and the underbelly would stop dripping water.

After they replaced the tank I took it out and once again the underbelly filled with water. I took it back to the dealership. They connected trailer to city water and left the gray tank valves closed. They told me they could not make it leak.

So on my recent camp trip I connected to city water with gray tank valves closed. Within 3 or 4 days the underbelly was dripping. I then opened the gray tank valve that services the shower and the 2 bathroom sinks and within a few days the dripping stopped. Could the anti-siphon valve be the issue? My anti-siphon valve is under the bathroom sink in the bedroom.