Just moved into a new house and had a new washer and dryer delivered today. When they installed them, they said they couldn't complete the washer install due to this cap on the drainage pipe.

They mentioned it might be a knockout, but, in trying to knock it out, all that's happened is my knocking out a chunk of it. I then decided to drill a hole in it and see if I could pull it out with pliers, which didn't work.

So, what is it, and how should I go about getting through it for the drainage line?

Cap over drainage pipe

  • Hello, and welcome to Home Improvement. Are you sure there's a drain behind that cap? And, you should probably take our tour so you'll know the details of contributing here. Nov 8, 2020 at 1:53

1 Answer 1


It appears that the original knockout was removed but a safety plug/cap was put on the pipe and not removed before gluing up. Can you get a pair needle nose pliers in that little notch and see if you pull up on it?

I would drive a screw into it, leave it and tie a string to the screw. Take a Dremel or some other rotary tool and cut around the perimeter , or a razor knife or a small chisel and hammer.

The screw/string will keep the cut out part from falling down the drain.

  • I looked down in there and it's definitely a pipe, just gotta figure out the best way to go about getting into it. I'm going to give the X-acto knife a go and see if I can't cut around it. Nov 8, 2020 at 2:20
  • 1
    Make sure the cut out does go down the pipe, could cause problems.
    – Alaska Man
    Nov 8, 2020 at 2:23

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