I have an unfinished basement that has rough-ins for plumbing. I would like to finish it some day, and I'm trying to envision what a bathroom would look like.

What purpose are the pipes for? Toilet? Tub/Shower? Sink? Wetbar?

basement pipes

1 Answer 1


The small one in the top left coming out of the floor is likely for a shower or tub. The larger diameter pipe coming out of the floor is almost certainly for a toilet. The smaller pipe to the right of the toilet that continues up is for the lavatory (i.e. sink).

You can tell these things because:

  1. The toilet requires a 3" rough-in.
  2. Showers and tubs require rough-ins within the floor and the rough-in must contain a P-trap. So you can confirm that pipe in the top left is for a shower or tub by taking off the cap and pouring some water in it. If it "fills up" some before draining, you'll know it has a P-trap and is indeed for a shower or tub.
  3. The sanitary tee in the pipe that continues up is placed approximately correctly for a vanity sink.
  • Works for me the stubs look a bit tall but better tall than two short.
    – Ed Beal
    Aug 3, 2018 at 23:34
  • I don't think it merits a dedicated question -- but is there a standard way to pop that cap off, to test if there's a trap? I don't want to cut the PVC yet :)
    – jglouie
    Aug 6, 2018 at 16:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.