3 Holding tanks?

[Ken1]

I recently bought a 1986 Winnebago 31' Chieftan  as a project. I discovered it has 3 holding tanks. Can some one tell me what drains in to which tank as they are displayed on the monitor panel as 1 2 and 3 + the fresh water tank.

[DaveVA78Chieftain]

You would need to contact Winnebago for a plumbing diagram.  Outside guess based on floorplan:
Black tank - toilet
1 grey - Shower
1 grey - Kitchen and bathroom sink.

Dave