Fill , wash, drain, flush...
A lot of the systems on the truck have something to do with water. This page branches to others with the various water sub-systems.
This covers the filling system, including retractable hose, filters, level sensors and holding tank.
This is the wash water holding system.
This is the toilet and its holding tank system
The bathtub, gray and black water holding tanks all use remote controlled electric valves. Here are the details on that valve.
This covers the water heaters and their heat sources, including LP gas, 110 VAC electric and engine heat.
The pump and accumulator fit in next to the gray water tank.
This isn't really part of the water systems, but it sits in the loop... Details on the installation of the tub system.