I have a question, I need to lower the Sanitary T due to new sink being lower and garbage disposal out being lower then the wall out. Luckily the pipe is vertical in wall. The old T that you see in picture, is 2 inch coming from basement, 2 inch to kitchen sink and then 1.5 inch up to upstairs bathroom sink.

My new sink is lower and is only a single drain now instead of a dual sink.

enter image description here Should i put a 2 inch to basement, 1.5 inch to kitchen sink and 1.5 inch to upstairs or still do 2 inch to basement, 2 inch to kitchen sink and 1.5 inch upstairs.

How is it best to glue these new pipe fittings together if there is not much play to them. To ensure enough of pipe gets into the fitting. (Glue the New T First), then use a hard coupling 1.5 inch to the old 1.5 inch to upstairs?

  • Clear, concise, includes well labeled pics... Nice first post!
    – FreeMan
    Commented Jun 26, 2020 at 18:08

2 Answers 2


You might need to use a Fernco coupling to get everything hooked back up. It's a rubber coupling with hose clamps to hold the rubber in place like this:

enter image description here
Source: SupplyHouse.com No endorsement of the vendor intended or implied - they just had a nice pic.

I'd use it on the 1 1/2" pipe up to the 2nd floor. Slide it on the 1 1/2" pipe, up and out of the way, hold it up with a piece of tape for now.

Glue a piece of 1 1/2" pipe in the top of the new sanitary tee.

Slip the new sanitary tee in place, glue it to the drain going down. The 1 1/2" piece sticking out of the top should just about touch the 1 1/2" piece coming down from upstairs.

Pull the tape and slide the Fernco down over the stub of 1 1/2" pip out the top of the sanitary tee. Tighten the hose clamps to spec.

Use 1 1/2" pipe to finish the trap to the new sink. You could use a screw together (slip joint) trap to make it easier to assemble, adjust, and take apart when someone drops something important down the drain.

  • When you say Y are referring to the sanitary tee ? Y makes me think of a Wye fitting which is a different fitting then a SanTee.
    – Alaska Man
    Commented Jun 26, 2020 at 18:37
  • Yeah, my bad. I do mean the T, I'll update
    – FreeMan
    Commented Jun 27, 2020 at 1:23

I'd use a 2" to the basement, 1.5" to sink and 1.5" to upstairs. Glue the section of the tee to the basement first, then get your straight 1.5" piece and glue it to the top of the tee. Get a pvc slip connector for the 1.5" to 1.5" pipes. Get all your pieces and play around with them to see the best way to position them to the disposal.

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