Unused PVC pipe nub sticking out of wall — can I recess it or cut it back behind drywall?

Working on a room that was an add-on from the 70s or 80s. We're removing wood paneling and plan to float/texture the drywall underneath for a cleaner finish. Problem: there's a short nub of what looks like PVC pipe poking out of the wall with no apparent purpose.

My best guess is it might be an old exterior drain line that was abandoned when the addition was built, but I honestly don't know. It doesn't seem to be connected to anything active — no water comes out and it's been this way as long as we've owned the house.

A few questions:

  1. Can we cap it and recess it behind the wall so it's not visible?
  2. Are there any risks or code issues with having capped plumbing inside a finished wall?
  3. Anything I should check before assuming it's truly abandoned/unused?

https://preview.redd.it/1mk4smouwp0h1.jpg?width=4284&format=pjpg&auto=webp&s=1b060db907bbd8f8a90548c4c1b0cba3f05b59c7

https://preview.redd.it/dy6v3mouwp0h1.jpg?width=4284&format=pjpg&auto=webp&s=70b9f75f97952da27a67a243f8e488e98a1e462e

https://preview.redd.it/jrzm4nouwp0h1.jpg?width=4284&format=pjpg&auto=webp&s=4b4bdfcd73e35e0e9386f3ec01ce7ee92de1b4d4

Posted May 12, 2026, 2:37 PM UTC

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