Coachmen Prism Drain Valves

[BackAgain]

ON our 2020 Coachmen Prism, we have black water and grey water drain valves, and on the other side of the rig, directly opposite these valves and, it seems like, connected to them, is a third valve. Can anyone tell me what this third valve does?
Thanks - Tom

 

[Rob&Deryl]

My guess is it the 2nd gray tank.
Depending on the floor plan, there is often a black & a gray for the bathroom and a 2nd gray for the kitchen so to avoid long plumbing runs.

 

[BackAgain]

Just heard from Coachmen. By regulation, there has to be a valve within 18" of the black water tank, so it turns out both this one and the regular black water valve need to be open to empty the black water tank. Good to know. Wish it appeared in the Owner's Manual app.