Dishwasher Drain Line

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by do-it-yourselfer, Aug 25, 2008.

  1. do-it-yourselfer

    do-it-yourselfer New Member

    Messages:
    2
    Location:
    NC
    I'm getting ready to replace my garbage disposal. The guy at Lowe's said I should be able to see the dishwasher drain line connected to my old garbage disposal. It's not connected to the garbage disposal and I don't see a line anywhere under the sink that could be from the dishwasher. When I look inside the cabinet beside the dishwasher the only thing I see is one water line going into where the dishwasher is located. I can't figure out where the drain line would be? My house sits on a slab, no crawl space. Any ideas?
  2. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    There may be a standpipe behind the dishwasher.
  3. kingsotall

    kingsotall Plunger/TurdPuncher

    Try taking off the toe kick to your DW (usually 2-4 screws) Shine a light under the DW and see if you can see the standpipe Redwood referred to. Be aware that beaty red eyes may be staring back at you...
  4. do-it-yourselfer

    do-it-yourselfer New Member

    Messages:
    2
    Location:
    NC
    Where would the stand pipe drain too?
  5. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Your guess is as good as mine...
    Whatever line they tied into.
  6. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,362
    Location:
    Yakima WA
    The problem here is while we can tell you how the dishwasher should be plumbed, we can tell you how is actually is plumbed. We DIYers sometimes do some crazy things that, in spite of being totally wrong, seem to work OK...at least for awhile.
  7. Southern Man

    Southern Man DIY Hillbilly

    Messages:
    530
    Location:
    North Carolina
    They started connecting dishwashers to the in-sink disposers sometime between 4 and 12 years ago. I know this from experience working on my own stuff, same brand of disposers. Older set ups used a standpipe as part of the sink drain with an air gap, similar to a clothes washer connection. If yours works, then don't mess with it. There is a knock out plug on the new disposer that you can then just leave in, and plumb the disposer just like the one that you're replacing.
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