Gray tank issue-toilet paper and excrement coming out

[Wisconsin Retiree]

I religiously use a cup of dawn dish soap added to my tanks after they are dumped with appropriate black tank treatment. When I head to a dump station I always dump a cup of borax in the blank tank for the ride there. This sloshes around & helps clean inside tank as well as sensor heads. Obviously, the key is use enough water when adding solids or paper to the tank. I also dump a cup of vegetable oil in once a month I was told it helps vavle gate to slide. I can't confirm it is true other than my valves do pull & push pretty effortlessly but they also aren't that old yet...

[firestation12]

Originally Posted by JMGJR

I have a 2021 3855BR.

I have been having an issue with the bathroom/shower gray tank. It would register as full (and start to back up in shower so I know it was really full) but when I open the valve the water would come out slowly (when I open the kitchen sink gray tank it comes out with a whoosh!!).

I bought a flush king so I could try to fill it up and get it cleared. When I filled and then pulled the valve I noticed that toilet paper and poo was coming out? I had my black valve closed and I am sure the valves are labeled correctly. It is obvious when I empty the black tank that it is what should come out of a black tank (but that also comes out slowly too). I filled and emptied it at least 10 times and was still seeing stuff come out that should not be in a gray tank?

Any ideas on what could be going on?

I didn't see that anyone had asked the question, which valve when pulled, caused the water that was backed up into the shower to drain?? That piece of info might help to determine which valve dumps the gray tank.