What on Gods Earth Is This?

The black abs pipe made sense until you get to the top of the pipe then it goes back down under the house. It is trapped, I have at least 3 inches on the arm, then it goes down into the drain. Good, but what is this mess to the left of it? the pipe makes a big “U”. Like, who designed this mess? Any reason? Ok, go!

Any photo where it goes under the house?

No, sorry. To be honest, I wasnt focused on it by the time I got to the crawl, because It made no sense as to why it was like that. I couldnt even guess a good excuse for it.

is this under a kitchen sink that is on an island or peninsula? (no wall for the vent pipe to hide in)

If so, it may be an “Island Loop

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Possibly some funky way they ran to connect to another vent pipe…

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There is no wall behind it, thats why it goes down to the crawl after the trap. I wondered about the connected pipe to the left of it. It all one big black pipe that both go to the crawl.

I guess you can say it sits on an island.

Island loop. its an alternative to an AAV (aka “Studor valve”)

can be used when there is no wall behind the sink to hide a vent stack.


It is supposed to be like this:

" An island vent rises as high as possible under an island before running to a regular vertical vent . It keeps air in the drain system and prevents siphoning of the P-trap. Tip: If you plan to attach a garbage disposer to an island sink , replace the sanitary tee and cleanout adapter with a flat-patterned cleanout tee."

Edit: You were too fast for me, Bert! :smile:


Dang, we learn something everyday dont we? wow. Thanks

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Im amazed. Ive not seen this. So greatful

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Me too! On my mobile trying to bring things up! Lol

Im sitting here laughing at myself because I am thinking that the people who put that there are the idiots. At least I find it comical.

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Here in my office I have three large monitors for cut-and-paste races just like this one. Ha Ha.


I’m in bed lol. I have my desktop set up with three as well :slight_smile:

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Note: AAV’s are not allowed in all jurisdictions, thus the frequent use of island vents when not in an island!


Great post Boyz!

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Is that some kind of flex ABS behind the trap? If so, it’s a no-no. :smile:

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That’s solid ABS

Yep, I normally find an AAV there, here in NC.