Originally Posted by Mottle
.... I just bought the camper and not sure what all the problems are and what may have been done to it before I got it. There is evidence the plumbing has been worked on before.
Hmmm. If it has been modified, it's going to be hard for anyone to help without pictures. Here's what to keep in mind. The city water enters the TT at the wall of the trailer. There is a one-way valve right there. It could be closed, but it is designed to open (push forward) under pressure. Disconnect your hose and remove any screen washer and check it out. Usually a little plastic plunger that you can push forward, gently. From there you are in the cold water system. From there it feeds all cold water taps, including the toilet, and goes to the input of the water heater. There's no magic, nothing complicated. Unless, of course, somebody modified something. Good luck!