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Thread: Leak at P-trap/drain connection with new kitchen sink

  1. #1

    Default Leak at P-trap/drain connection with new kitchen sink

    Hi,

    My issue is that I installed a new sink that is deeper than the previous sink, where my output pipe from the garbage disposal is slightly lower (almost an inch) than the drain out thru the wall.

    I tried to add an extension between the drain out and the J-pipe connection, but had a single leak at the point where I hacksawed the extension pipe to get it right at where the J-pipe connected to it. I've never messed with plumbing before, but I'm thinking you can't just add a movable washer to the end of a sawed off pipe for the tip of the J-pipe connection.

    I've only gone to Home Depot for parts, so I'm hoping that maybe a specialty plumbing store will have an expanded parts section.

    My exact measurements with this problem are:

    - drain out to floor distance: 16 & 1/2 inches
    - garbage disposal output to floor distance: 15 & 1/4 inches
    - drain out to garbage disposal output distance: ~6 inches

    Any advice would be great.

    Thanks,

    Jim

  2. #2
    DIY Member coz's Avatar
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    if your sinks lower you would have to cut down the 90 that comes out of the disposal and shorten your tailpiece if you have a double bowl. i dont understand what you are extending

  3. #3
    DIY Senior Member TedL's Avatar
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    Stuff does not flow uphill. You need to lower the inlet at the wall, raise the sink, or lose the disposal.

  4. #4
    DIY Member coz's Avatar
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    he may be able to build a slightly larger trap to make up the diff

  5. #5
    DIY Member coz's Avatar
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    is it a single bowl sink?

  6. #6

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    It's a deep single bowl with a garbage disposal, where the outlet straight out of the garbage disposal is an inch lower than the drain out thru the wall.

    It does seem funny to think that the water should flow uphill by an inch, but I was hoping that by the nature of the p-trap (to keep water blocked between the sewer and your sink drain) that the less than an inch differential wouldn't matter that much.

    Other people must have similar problems like this, right? Or am I the only guy who lets the wife pick out an sink without measuring the drain outlet?

    Is my only course of action to move the drain in the wal down by an inch or two?

    Thanks,
    jim

  7. #7
    DIY Member coz's Avatar
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    use a regular 90 into the trap instead of the street 90. you can add a small piece of pipe inbetween giving your trap an extra inch.

  8. #8
    Commercial Plumber markts30's Avatar
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    I would think the best bet would be to cut into the wall and lower the drain to make this piping work...

  9. #9
    DIY Senior Member TedL's Avatar
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    Quote Originally Posted by coz
    he may be able to build a slightly larger trap to make up the diff
    Larger in what dimension? Making the trap larger vertically would only drive the outlet further away from where it needs to be. And larger horizontally wouldn't change the height.

  10. #10

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    The problem with moving the drain is that it's encased in a brick wall (which seems like it would be a huge pain to break into to move it down only an inch).

    Our other option of not having a garbage disposal seems easiest to fix the problem, but not a good thing to do (with the dishwasher we just added).

    I think I'm starting the consider replacing the sink I installed with a slightly shallower sink. The wife already found a similar one that is an inch less deep than the one I put in already (which is all I need to get the garbage disposal output lined up with the drain). Are there any problems with have a straight output from the garbage disposal into a p-trap?

    Or I just bridge the pipe gap and have some water always sit at the bottom of the garbage disposal. I know this isn't optimal, but would this cause major problems with the functioning of the garbage disposal over time?

    Thanks for the help everyone,

    Jim

  11. #11
    Retired Defense Industry Engineer jadnashua's Avatar
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    The outlet of the P-trap to the wall should slope down at 1/4"/foot. Sounds like the shallower sink is the best option here.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  12. #12
    DIY Senior Member TedL's Avatar
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    It is especially problematic to try to get solid stuff to flow uphill, and sending solids down (up?) the drain is the modus operandi of a disposal.

    You have solid brick between the sink base cabinet and the pipe?

  13. #13
    Commercial Plumber markts30's Avatar
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    If the drain line is in a brick wall and you don't want to go to the trouble of moving it down a couple inches, go with the shallower sink...
    Make sure the disposal outlet is slightly higher (1/2" or so) that the drain inlet at the wall to allow for fall..

  14. #14

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    Hey, just a follow up on what I did to solve my problem ...

    I got a sink 2 inches shallower and everything fits great now (had to use one of those flex-end p-trap for the bend from the garbage disposal into the Jpipe though, since no a lot of spare room).

    We've been running water and garbage thru it for a few days now and everything seems fine.

    Thanks to eveyone for helping me realize that the p-trap wasn't a magical device that would puch water up an inch ...

    Jim

  15. #15
    Moderator & Master Plumber hj's Avatar
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    Default P trap

    It sounds like you did it almost right. That flex P trap is bad news.

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