The bathroom sink drains into the black tank. They are set up that way to make sure your black tank has enough water to push out any solids in the black tank. The galley sink feeds into the grey tank. If the valves are pushed in, they are closed. If the black tank is on the passenger side of the coach, there is a 2nd valve on the passenger side that is used to close off the black tank from flowing through the crossover pipe to the dump station on the driver side. That valve needs to remain closed until you are ready to dump the black tank. It is a safety feature to keep the black tank from leaking in the event you should break or crack that crossover black tank pipe while driving. The black tank must not leak onto the roadway. I usually set up my sewer hose at the dump station and open the black tank valve there. I then walk over to the passenger side and open the other black tank valve to release the black tank fluids out. I checked the specs for your coach, you have 1 grey water tank, 1 black water tank and 1 fresh water tank.
Paul
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