Under lav PEX vent.

[nkyrvguy]

Hello,

Does anyone know what the black vent/air gap device is used for in the picture?

The problem is that when traveling we get an intermittent water leak that gets the stuff in the cabinet wet. I cannot make the faucet nor the drain leak. I figured water was somehow leaking/splashing out of this thing. I don't know where the two blue pex lines go to. Maybe the potable water holding tank?

Note: The picture rotated when uploaded. The group of pipes go down into the floor vertically and the black vent is like a cap.

Thanks

[ynpmoose]

Vacuum breaker. Usually for your blank tank rinser to keep it from sucking black water backwards.

https://www.amazon.com/dp/B07P75Y1MR..._ZvGlDb5BQHKMD

[Berjr]

Are you the original owner? If not my thought that it could be a fresh water tank vent routed high and back down to break the suction effect

[dannyabear]

Originally Posted by ynpmoose

Vacuum breaker. Usually for your blank tank rinser to keep it from sucking black water backwards.

https://www.amazon.com/dp/B07P75Y1MR..._ZvGlDb5BQHKMD

Improperly installed vacuum breaker, it should be installed up and down, not sideways

[Grumpy]

Originally Posted by dannyabear

Improperly installed vacuum breaker, it should be installed up and down, not sideways

As OP mentioned pic is sideways, not vacuum breaker.

[dannyabear]

Originally Posted by Grumpy

As OP mentioned pic is sideways, not vacuum breaker.

OK, I missed that, next step is just replace vacuum breaker, less than $10 at Lowes or home depot

[Rustynuts]

So we have one in our 1/2 bath in our Seneca and have also noticed a drip or two. We occasionally have a smell from the black tank that I have unable to track down and now I am thinking it may be this valve sticking and venting into the bathroom. Cheap enough to just try.

[dannyabear]

Originally Posted by Rustynuts

So we have one in our 1/2 bath in our Seneca and have also noticed a drip or two. We occasionally have a smell from the black tank that I have unable to track down and now I am thinking it may be this valve sticking and venting into the bathroom. Cheap enough to just try.

Because of food scraps, etc. in the gray tank, they will smell as bad as a black tank, AAV is usually the culprit, if the toilet holds water

[nkyrvguy]

Originally Posted by ynpmoose

Vacuum breaker. Usually for your blank tank rinser to keep it from sucking black water backwards.

https://www.amazon.com/dp/B07P75Y1MR..._ZvGlDb5BQHKMD

I didn't think about the black tank rinse. I will hook a hose to that and feel if water is going through the pipes.

[nkyrvguy]

It was indeed for the black tank flush.

I checked to see if it leaked when I cycled the rinse water on and off. No leaks found. I will keep an eye on it next time out.

Last time I was flushing the tank, I was curious how the clean supply was protected as I did not see a check valve directly behind the water panel.

Thanks.