The washing machine in my basement drains into this utility sink. On the end of the washing machine discharge, there is a lint catcher. Can anyone tell me what this white pipe is that comes up and is open at the top near the sewage stack? There is a bad sewage smell that comes out the top of this pipe and I'm wondering why this pipe is here and open? The p trap where the utility sink drains is supposed to leave water in there in order to prevent smells from coming back up, right? As a side note, the sink drains slow. It's hard to tell, but at least part of it seems to be from the small drain cap that I leave in when the washing machine drains. I've debated even if it would make sense to have the washing machine discharge directly into the sewage stack to avoid having to go through the utility sink altogether. I'm not sure why this wouldn't have been done in the first place either? The house is older, built in the 1950s.

Sewer stack with open pipe

Plumbing below the utility sink

Utility Sink Drain

1 Answer 1


I'm guessing that the white pipe you're referring to is the original drain for a washer. The extension piece fastened with duct tape might have been added because the washer draining caused some water to overflow out of the pipe.

The slow draining could be due to partial blockage. You might want to remove the trap and clean out the pipes. Scum can build up above the trap over the years and can smell. Try removing that extension piece and put the washer drain pipe, minus the lint catcher, into the pipe and see how it works out.

  • Take the clean-out cover off the iron stack and let's see what's going on in there while you do it. +1.... Uh, 2" wet vent... ok I guess, but not really; not if it's causing the trap to get sucked dry. It comes almost close but doesn't look like an S trap.... New cover on the stack says this has been a problem before.
    – Mazura
    Jun 22, 2023 at 2:00
  • Thanks for the responses! Couple of follow up clarifications. 1. To be clear, you're suggesting to remove and clean the white p trap, not the iron sewage stack cover, right? Any proper way to clean the pipes? 2. If the white pipe with the duct tape extension was the original drain, any guess why it was moved to drain into the utility sink? Could it have drained too slow and backed up the washer? It is a top load washer, so lots of water drains out. 3. If I did try draining into that white pipe, would be an issue that the wet vent is removed (if that's what that is based on the other comment)?
    – Panda
    Jun 22, 2023 at 12:24
  • 1
    @Panda Yes, I'm suggesting removing the white trap. The back rubber cover for the stack and the access cover from the floor can be removed if further investigating is needed for a blockage. Any tube can be used to clean the PVC fittings. It's anybody's guess about the draining into the sink. The pipe might have been extended due to over flow and then a new washer was installed and it's drain couldn't reach the op so it was stuck in the sink. Don't know if it would be an issue, that's where the trial and error comes in.
    – JACK
    Jun 22, 2023 at 13:11
  • @Panda That would be any tube brush can be used to clean the PVC fittings.
    – JACK
    Jun 22, 2023 at 15:39

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