Dishwasher filling with sink water

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by my3angels, Jul 26, 2011.

  1. my3angels

    my3angels New Member

    Messages:
    8
    Location:
    Redding, CA
    I read a previous post about sink water backing up into the dishwasher, and the suggestion of a 'gap' being installed, but my sink and dishwasher have a little different issue than that post.
    My sink & dishwasher drain well, but I noticed a sour smell emerging from the dishwasher yesterday, and found 'dirty' water about two hours after emptying it. It appears the sink is draining into the dishwasher, leaving 'dirty' water to pool into the bottom of the dishwasher, even though the sink drain appears to be clear. Any ideas why this would suddenly start? I bought the house (lemon) four years ago, and this is the first problem like this.
  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,943
    Location:
    Bothell, Washington
    And that's why you would install an air gap. It prevents water that has been in the disposer or sink from going back to the dishwasher.

    [​IMG]
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,537
    Location:
    Cave Creek, Arizona
    You must have a sink drain problem because that is about the only way that water could drain, or be siphoned back into the dishwasher. If so, an air gap would solve the symptom, but not the problem.
  4. my3angels

    my3angels New Member

    Messages:
    8
    Location:
    Redding, CA
    In the meantime, can I drain the dishwasher and plug the drain at the pipe? Will this prevent the sink water from draining into the dishwasher until I can hire a plumber? I can handwash dishes until then, but I don't want to cause more bacteria to build up in the dishwasher until it's fixed. Can you also give me an average price for an air gap so I have an idea what my expenses will be?
  5. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,137
    Location:
    Maine
    Like HJ said, installing an air gap won't fix the problem which is a plugged sink drain. You can clamp vice grips on the dishwasher hose until you get the drain fixed. Oh and dump some clorox in the bottom of the dishwasher and run a cycle to clean it out.
  6. my3angels

    my3angels New Member

    Messages:
    8
    Location:
    Redding, CA
    Thank you for all the help. I got a snake, and cleaned the pipes, but I will block the hose until I can get an air gap installed. Thanks for the reminder about the bleach for sanitizing also.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,537
    Location:
    Cave Creek, Arizona
    IF the drain is open and you do NOT use the dishwasher, there is no need to "block" the hose.
  8. Impossible to know what causes an intermittent problem (in any system, not just plumbing) until you expend a lot of time diagnosing possibilities.

    So far, I haven't read any mention of the positioning of your dishwasher drain hose. Did you write that out somewhere already? The next best thing to an air gap is a hose that is positioned in a HIGH loop upwards to the underside of the countertop and back down to the connection point with the drain pipes. That configuration geometry is known as a "high loop". The hose goes up, up, and up. Then it goes down down down.

    What is the positioning of your dishwasher drain hose?

    The advantage of an air gap is that it TELLS you there is a problem. You were lucky to have spotted it by yourself.

    What to do next? Diagnose, diagnose, and diagnose.
  9. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,792
    Location:
    Long Island, NY
    All the sink tailpiece adapters for dishwashers I have seen are a Wye type shape, so unless there was a partial clog in the drain below the adapter, I don't see how running the kitchen sink would allow water to flow up the wye. then again, maybe your tailpiece adapter is not a wye, and you don't have the high looped dishwasher hose configuration either. I believe there is a partial clog below the adapter. Is there a garbage disposer in this setup too?
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