As part of a full bathroom renovation, I am removing a mid-section half-wall that separates toilet/shower from vanities/cabinets (now removed!). In the process, I discovered a white PVC pipe with a label "Not For Pressure". By a quick inspection, I see no exhaust on the roof around the same area, nor I see any water heater exhaust coming from the level below to this bathroom. I don't think this pipe carries water. So can someone chime in with any insights or ideas? Thank you!

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  • 2
    Looks like a drain vent stack. Can you look in the attic to see where it goes? It may not come straight up through the roof right there.
    – jay613
    Oct 13, 2021 at 18:38
  • Thank you Jay! I think you're right. I will try to access attic to assert this for certain. Oct 13, 2021 at 19:19

1 Answer 1


It is probably a drain vent. It could be sharing a vent cap with other vents so it could come through the roof at a different location.

  • Thank you Jack! I will try to access attic to see if i can verify this for certain but I suspect you and @jay613 are both right about this. As a followup question, I wonder if I could (it's safe) add elbows to re-route this pipe to make it flushed into the floor, then wall so I can completely get rid of the wall? Oct 13, 2021 at 19:18
  • 1
    Probably not, unless it's only venting things on the floor below, which is unlikely (more likely to be venting things on this floor, below the floor, which is NOT the floor below for this plumbing vent code purpose.) Vents must be "vertical" (which is actually defined as 45 degrees or more) until they are 6" above the flood rim of the highest fixture on the floor served by the vent. Look, take pictures of what it vents and how, post those in a new question.
    – Ecnerwal
    Oct 14, 2021 at 0:15
  • @Ecnerwal Thanks.. I wasn't sure about that so didn't comment. You definitely are not a toxic anti DIYer ... lol
    – JACK
    Oct 14, 2021 at 11:54

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