I have a shower on the first floor that does not have a P-trap. A previous owner did some remodeling and the shower drain pipe is plumbed right into the top of the waste line with a tee. You can see the connection just behind the supply lines at the back of this picture: Picture of shower drain line The flow is from the back left of the picture to the front right. The tee closest to the camera is from the toilet. The piping runs a few feet further and then joins the soil stack.

What are my options for adding a proper P-trap here? can I put a pair of 45 degree fittings to jog the shower pipe around the waste line, add the P-trap and then rejoin the waste line from the side instead of the top? Is there some other approach?

This is all above the ceiling in a finished basement so I know I will have some drywall work to do no matter what.

  • Wow I would open it up as close to the shower drain as possible and add your trap, you will need more than 2 45's because you need to create a u or 4 90's – Ed Beal Jul 1 '18 at 0:00
  • What is the size of the drain pipe for the toilet. It looks small. – d.george Jul 1 '18 at 11:46
  • The drain pipe from the toilet is 3", same as the main line. – Jim S. Jul 2 '18 at 22:38
  • @Ed The 2 45s would be used just to jog the pipe away from top dead center of the main line. Then I would drop down and install a normal P-trap that enters the side of the main line at a different location. I would have to cap off the remaining stub on top of the main line. – Jim S. Jul 2 '18 at 22:48
  • Ok I could not see that from the photo , it will make running a snake harder if needed but would work. – Ed Beal Jul 2 '18 at 23:15

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