A good place to start looking is near where your city water inlet is. All of the coaches I have owned and worked on have had the water pump located in close proximity to the water connection.
1972 Winnebago Brave D20T
1993 American Eagle 38A (Currently dead in Bakersfield, CA. Know a diesel mechanic?)
2003 Chevrolet Tahoe w/Remco Disconnect - SOLD