Hi I just framed out my laundry room in my basement and I'm looking to run add a utility sink and I need to add a drain line for both the washer and the utility sink though the utility sink is going to be the left of the washer so I'm not sure how I would branch off a drain from the washer drain. Here is a picture to make things a little easier to explain.

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The utility sink is going to be to the far left and originally there was just a trap coming off of where the main drain line which I cut.

If I was having the utility sink before the washer near the main drain this wouldn't be an issue but since I need to run a trap for the washer how then do I branch off of that to run the line for the utility sink? Thanks


If it were me, I'd install a new sanitary tee in the main drain, just above the existing sanitary tee. I'd have the standpipe for the washer come down into a P-trap, and connect the other end to the new tee.

However, you'll have to make sure the standpipe is at least 18" above the trap weir. If that height cannot be maintained, you'll have to move some things around.

I'm also not sure if a proper P-trap will fit in the stud bay, so you'll have to measure to verify. The minimum length of a trap arm is two pipe diameters. So if you're using 2" pipe, that's 4" from trap weir to the sanitary tee.

Then I'd have the trap from the washtub, connect to the existing sanitary tee.

Basically, something like this...


Minimum drain lengths

  • Thanks for the help, after doing some researching and talking to a friend who is a plumber I decided to run the sink to the right of the dryer, so I put in a sanitary tee like you said but faced it the other way and ran that for the utility sink drain and then the original lower branch I ran to the washing machine and it turned out great.
    – Greenhoe
    Jan 21 '16 at 6:26
  • 1
    @Greenhoe If you get a chance, edit a photo of the finished product into the answer. It's always nice to see the results.
    – Tester101
    Jan 21 '16 at 10:45

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