Welcome to the forum! Your water problem is most likely from a backflow preventer whose failure is a common problem. Some of us have just eliminated it and gone with an external one and others have replaced the cheap plastic one with a metal one from a box store. Many threads on that here.
Dick, Joyce, Diego, Picatso and Gustav
2017 3720 RL, and 2013 HC 343RL
2017 3500 Dodge Maxi DRW 4X4, Pullrite Hitch, IS, Disk Brakes, 3rd AC, Winegard Traveler, Bathroom door mod, Dometic 320, couch for desk swap, etc.