Just put a new sink in and was not lucky enough to have the plumbing line up. I have it roughed in and wanted some insight/opinions on whether this will work, or what I need to do to fix it. I have a slope leading from the disposal to the trap, but with the new larger sink, my p-trap is about 2" lower than it previously was. I used a J-bend to meet the drain tail piece to the drain tube. It seems like I am fighting gravity a bit too much now as the distance between the p-trap and the drain tube is quite large. Will this setup work or do I need to approach it a different way? enter image description here

6 Answers 6


Bring your Ptrap up or your Sanitary Tee down.

AS noted by others you can cut the tail of the piece where it goes into the top of the Ptrap shorter ( thereby bringing the Ptrap up ), This will allow you to have the down hill slope you need for the disposal. You may need a longer tail piece from the bell on the basin into the tee from the disposal.


I think this is the better option because your sanitary tee is a little too high.

You could cut your drain pipe shorter so the sanitary tee is lower.

Use a regular Ptrap ( non flexible, there is no need for the debris catching flex connection here ).

You also need to mount your air admittance valve properly. It is not high enough, put it as high up as you can in the space between the bowl and the back of the cabinet.

If you put it on a threaded connection just above the san tee you will be able to pull it out to change it if necessary.

  • Thank you! I cut the drain pipe to lower the sanitary tee and it worked perfectly. Appreciate the help. Commented Sep 14, 2019 at 22:48
  • 1
    if it worked then please select the answer as correct. thanks.
    – Alaska Man
    Commented Sep 15, 2019 at 18:10
  • That was the right solution for a different reason as well -- now you won't have standing water backing into the garbage disposal, which would severely affect its longevity.
    – Dave Tweed
    Commented Sep 16, 2019 at 15:25

In the OP's installation the last horizontal run going into the vertical drain appears to be slightly higher than the horizontal run coming from the disposer. I think this will cause the horizontal disposer run to retain liquid. It appears that some of any liquid waste going into the left sink drain would flow back into the disposer. It seems to me that the T in the final drain must be lower by 2 or 3 inches.

See how it is done here (https://terrylove.com/forums/index.php?attachments/kitchen-sinks-jpg.15470/):

drains for double sink with disposer

In the OP's installation the tailpiece from the sink appears to be out of alignment (at a slight angle) with the next piece below it. But this may be an illusion since it also appears to be the case in the installation shown above.

  • Thanks, that is exactly what i did! Commented Sep 14, 2019 at 18:00

You DO realize you can (perhaps even "are supposed to") cut excess length from the slip-fit trap parts? They are supplied long, but don't need to STAY that way. You can cut most of the tube leading to the trap off, thus raising the trap.

Opioninated commentary: I'd also lose the "flex section" on the other side of the trap - it is the part of this setup that will break first, by a long shot, in most cases. Also helps to promote clogs before then. You should be able to line rigid parts up by rotating them. In this case looks like you might also need to trim the "J tube" slip-fit end to make them line up right.

  • The slip-fit trap is cut. I used the old setup as a template and cut it down even more, there will still be about a 2 inch gap between the p-trap and the drain pipe. I think I just need to pull it out and start over with the advice I've gotten here so far. Commented Sep 14, 2019 at 15:01

The flange piece connected to the sink looks like it isn't mounted flush and could cause leaks. Readjusting the garbage disposal might fix that. It also looks like you have enough room to get rid of that adjustable trap and install a regular one. The "jog" in that trap and the excessive length will probably cause water to rise into that sink when you run the disposal.... Good luck.

  • Thanks, I will adjust that flange and see where I am falling short on the trap/drain connection. Commented Sep 14, 2019 at 15:00

Maximum water trap height is 4", that's the distance between bottom of P trap and height of P trap outflow.


Cut your T off and move it down is the way to fix this. Leave the T upstream of your trap connected, cut the T off the pipe coming through the floor approximately an 1"- 1.5" below the T. Eliminate the flex piece and screw your trap together. This will give you a gauge of how much more pipe to cut off the drain to insert a coupling. Done. Extend your cheater vent. The way it is currently plumbed with a disposal unit, it will be plugged constantly

  • I cut the T down, now can you explain the cheater vent? At its current height it is too low? I have a female connector so, insert male coupling and add a few more inches to the top of the vent? Thanks. Commented Sep 15, 2019 at 16:35

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