I replaced my garbage disposal with a new unit and attached it to the existing drain with the manufacture provided straight outflow pipe. The new disposal sits a little lower than the old unit, which also had a straight outflow pipe. The result is that the outflow pipe is now angled about 5º down towards the disposal.

I'm guessing that's a bad thing as the ground up food sludge will pool towards the disposal end. What slope angle should I shoot for?

Under sink plumbing connections

The level was just a touch too long to hold flat against the pipe, so that's why there's a gap. But you can see that the horizontal air bubble is just off to the T end.

The T connection on the left is a split 1.5" baffle. The connection on the garbage disposal itself is full rubber with a metal ring clamp, so it can flex to a wide angle if needed.

Is there a combination level + protractor + measure tool that could tell me how much I need to lower the T connection by? How would I go about dropping the T connection by such a small amount? I was imagining disconnecting the pipe and carrying it into a hardware store...

  • Is there a trap after this point? I’ve never seen it quite like this....
    – Tyson
    Commented May 6, 2018 at 18:36
  • @Tyson yes, you can see the compression ring for the trap joint in the bottom left of the picture. The trap flows into the sewer line at the back of the sink, which I just noticed is completely blocked by my hand and level.
    – Patrick M
    Commented May 8, 2018 at 14:37

2 Answers 2


The top part of the tee is a slip joint. You may be able to loosen the nut and slide the tee down the tail piece to gain the slope you need. ( the tail piece is the pipe that is from the basket of the sink and is going into the top of the tee.)

If the tail piece is not long enough then you can buy a new tail piece that is longer and cut it to the correct length. The slip joint allows for some play so you can adjust it up or down as needed.

  • I think we are saying the same thing. Cutting the bottom of the tee will lower the tee down closer to the P trap. You then may have a gap between the top of the tee and the bottom of the tailpiece so a longer tail piece may be needed if the slip joint is not long enough.
    – user76730
    Commented May 6, 2018 at 20:04
  • 1
    @user76730 We are not saying the same thing. Cutting the bottom of the tee does not lower the tee. Lowering the tee at the slip joint lowers the tee. It may be necessary to cut the bottom of the tee if lowering the tee then place the trap lower than it needs to be. but the only way to lower the tee is to lower the tee.
    – Alaska Man
    Commented May 6, 2018 at 20:09
  • Both the joint above and below the tee are slip joints. (Technically the tee is glue connected to vertical pipe) You should be able to loosen both joints and slide it down a half inch or so. Judging by the dirt ring on the lower pipe, it may used to be that way.
    – DaveM
    Commented May 6, 2018 at 20:11
  • I am assuming the slip joint is already bottomed out in the P trap therefore needing to be cut to slide down any farther. Of corse if it is not bottomed out then no cutting will be necessary.
    – user76730
    Commented May 6, 2018 at 20:20
  • The T was able to slip downwards, but the drain pipe coming from the sink only had about ~1/4" extra pipe. That was just enough to get the outflow pipe angled past level, but not by very much. Maybe a 1º downward slope.
    – Patrick M
    Commented May 8, 2018 at 14:11

I have never used a level for that. The rule of thumb is about a quarter inch per foot. From the picture it looks like you can just cut off about 3/4” off of the tee and reinstall it.

  • 1
    You may need a longer tail piece when you cut the tee
    – user76730
    Commented May 6, 2018 at 17:27
  • 1
    Why would you add a comment to your answer when you should just edit your answer to include the additional information? Comments at this site can disappear.
    – Michael Karas
    Commented May 6, 2018 at 19:16
  • 1
    Probably because I didn’t know answers could be edited once posted.
    – user76730
    Commented May 6, 2018 at 19:21
  • Well now you know. :-) It is comments that cannot be edited after 5 minutes from being posted. Answers can be edited by the original answer poster or other community members that have enough built up reputation.
    – Michael Karas
    Commented May 6, 2018 at 19:27
  • cutting off some of the tee does not change the slope of the pipe in question.
    – Alaska Man
    Commented May 6, 2018 at 19:49

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