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Thread: P Trap Problem Please help!

  1. #1

    Cool P Trap Problem Please help!

    I recently installed a deeper sink and am currently trying to install the p trap or any trap that would work.

    Problem: The horizontal drain line will be higher than the p trap and I am afraid this will cause draining problems.

    1. Will I have to lower the horizontal drain line to make this work? Or should I continue the install?

    I attached a picture to help understand.
    Attached Images Attached Images  

  2. #2
    Commercial Plumber markts30's Avatar
    Join Date
    Sep 2006
    Phoenix, AZ


    Best bet would be to lower the waste outlet in the wall...
    Drop it 6" or so and then just hook up the continuous waste as you are doing...

  3. #3


    I'm not sure if this will work because I'm not there but can you cut the tube for the sink drain and your white (horizontal) pvc will move up?


  4. #4
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    It appears what he means is the outlet of the trap will be LOWER than the connection point at the wall. Without the disposer, you could simply shorten the sink tailpiece. As it is, the proper solution is to open the wall and lower the tee. If you create a deep trap, it will drain slowly.

    Your dishwasher does not have an air gap. While your local code may allow that situation, the way you have it hooked up will allow dirty water to flow into that hose and back to the DW. Even if the DW has a check valve, at the least you may experience clogging of that line. You should loop that drain hose all the way up against the bottom of the countertop, and secure that loose with a clamp of some kind to hold it there.

  5. #5


    I would just install your p-trap the way it is and run some water to see how it drains. You can always tear into that wall later if your drain is too slow. And, watch what you put down that disposer--no potato peelings, onion peelings, rice, etc... That stuff will clog any drain.

    Definitely use some bailing wire and "high loop" your dishwasher drain as Jimbo suggested.
    Last edited by Verdeboy; 07-27-2007 at 09:10 AM.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    You really need to lower the connection in the wall otherwise you'll have standing water inside your disposal, and it will clog almost instantly. The waste must flow downhill. The disposal acts somewhat like a pump when it is running, but it won't be running all the time. If anything other than the trap has standing water in it when you aren't running the tap, you'll regret it.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014


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