Shower draining to galley tank

[rediscovering.John]

Hey guys, new member and first post here. I have a HAMPTON HP375DBL destination trailer. The model has 1 black, 1 galley and 1 gray tank. What I am see happen is that only the galley tank is filling up. The galley tank will fill during a shower and will back up into the shower and kitchen sink. At that point the galley will be full and the gray will be completely empty.

Does anyone know if there is a valve that shuts off the regular gray tank that's causing it to drain to galley?

[Max23]

Apparently no one has a clue on this one. Sorry.

[travelin texans]

I'm guessing they've mislabeled the tanks or pull handles, which is not unusual.

[chuckster57]

Originally Posted by travelin texans

I'm guessing they've mislabeled the tanks or pull handles, which is not unusual.

What he said. Have you ran the kitchen faucet to see which tank fills up?