I have a lance travel trailer 1685, I went on an extended trip, hooked up to water at camp grounds no problem, then my son had to fly and drive Trailer home because I hurt my arm, so him and his wife took a holiday also. When they came home and I hooked my water back to the trailer it made the regular water tank over fill, I think there is a valve that keeps this from happening? So now I'm running off tank with pump that I have to turn on and off and the water pressure is useless if you want a shower, is there a fix for this?