Problems with new wash drain bubbling up

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New Member
May 21, 2020
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Thank you in advance for any advice! For clarity, I've split the question up into a Background section, a Proposed Problem section, and a Proposed Solution section. It would be immensely helpful if some knowledgeable folks could take a look and let me know their thoughts on the Problem and Proposed Solution. Thank you in advance for any help!

We had our basement apartment remodeled by some contractors. As part of the job they took out our old bathtub and built a custom tile shower. While they had the walls open, they installed washing machine hook-ups that drain to roughly the same place as our shower (the apartment previously did not have a washing machine). The hookups face into a utility closet on the other side of the wall. We do not have any plumbing background and trusted the contractors to know what they are doing. The photos that are attached are from when the walls were still open (before the tile shower was installed).

I'm trying to solve for the fact that the water won't drain. It just bubbles up. It sometimes goes down after bubbling up, but other times it sits there until I flush the toilet.

Yesterday, we tried running the washer for the first time ever and unfortunately the water just bubbles up the drain pipe. At first, I hypothesized this was just a flow rate problem. I presumed that maybe the pipes were just too narrow for the 20 gallons per minute that he washer pump spits out. However, I tested this by slowly putting water down the washer box drain. The water slowly accumulated up the standpipe until it was near the top and then it sat there. Then I flushed the toilet, and WHOOSH the water drained immediately from the washer drain standpipe. I went back to look at the photo of the work while the wall was still open. There's a lot wrong with it. See attached photo that I'll call "Problem."

Proposed Solution
After doing some research on plumbing (I have literally never thought about plumbing before) I went back to look at the photo of the work while the wall was still open. There's a lot wrong with it, including the fact that we need to install a P-Trap. However, it appears to me that the reason why the water isn't draining is that the air admittance valve is on the wrong side of the drain. This, I think, is why it only drained after I flushed the toilet. I have attached a file called "Proposed Solution." Any feedback and help would be great! Thank you!



Well-Known Member
Feb 24, 2016
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Well a studor vent is to keep the trap from drying out. You have no trap. Pipes are big enough. But you need a way for positive air pressure to release. That valve only allows air in not out. When you flush the toilet and give it a push of air then she flows. For every gallon on water you put in drains. You must release a gallon of air. But that whole assembly looks like the plumber should be reported to bbb. None of it is correct.