What am I missing

[crmillsjr]

I have 3 gray tanks. One is for just the kitchen sink. When it is full, instead of just backing up in the sink, it floods the cabinet underneath and water comes spilling out on the floor.
Is there a valve or something that I am missing?

2020 Pinnacle 38FLWS

[TWP723]

Usually when a gray overflows and backs up, it will come out at the lowest point in the rig...like the shower drain. Are all grays full or just the kitchen one? I'd check the P trap and make sure it's good and tight.

[Onyrlef]

Originally Posted by crmillsjr

I have 3 gray tanks. One is for just the kitchen sink. When it is full, instead of just backing up in the sink, it floods the cabinet underneath and water comes spilling out on the floor.
Is there a valve or something that I am missing?

2020 Pinnacle 38FLWS

Just off the top of my head I'd check the coupler from the drain to the stack, if it's not leaking when it drains going in one direction but leaks when backing up it may be because the coupler 1 1/2" or 1 1/4" w/ sweep isn't glued, if it's an anti-siphon device the check valve could be malfunctioning.

[billcf7]

Your sink will be vented under the cabinet and is usually in the back corner. When your tank fills up water will come out this vent usally before you see it in the drain depending on height of vent

[RogerR]

This is what the vent looks like but may be a different brand. Supposed to be one way but they are cheap ones and the flapper fails to keep the seal. Or, as above, one of the sink drain joints is loose,,, or both knowing Jayco.