In addition to the 'faucet' style valves at the coach en of the washer hoses, many class A caches have a water distribution manifold that can selectively shut off water to any item in the coach.
The water manifold valve assembly in my Tour Master is in the curb-side basement bay that has the water filter, water pump, etc...
It is called a "manibloc" valve and looks like this:
https://www.google.com/imgres?imgurl...act=mrc&uact=8
Chuck