Strange dishwasher drain connection

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Daniel Myers, Apr 18, 2020.

  1. Daniel Myers

    Daniel Myers New Member

    Apr 18, 2020

    My dishwasher is leaking at the p-trap on the air gap side. I didn't do the installation, and I'm kind of confused as to what's going on.

    The dishwasher has its own drain line. It looks to me like the connection from the air gap to the p-trap is made by a copper pipe that is wrapped in rubber, about 1.25 in od. The p-trap is 2 in diameter black plastic.

    The connection between the line from the air gap and r p-trap is made using a slip joint with a step up washer; apologies if that is not the right term. Photo:


    This seems like a peculiar set up, particularly since there's a garbage disposal with its knockout plug for a dishwasher connection still in place. I don't see how a rubber wrapped pipe would give a good seal at the slip joint.

    Is this expected to work correctly? If so, any suggestions for resolving the leak? I've tried tightening the slip joint, but that hasn't helped.

  2. fullysprinklered

    fullysprinklered In the Trades

    Jun 15, 2014
    self-employed plumber-electrician doing residentia
    If I'm going beyond the reach of a d/w drainhose, my go-to hose is 5/8 automotive heater hose. A stub of 1/2in copper tube fits snugly inside the hose to transition into a connector. If that's the case for your setup, it may just need a band clamp to seal the hose onto the copper.
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