Two dishwashers one drain-no disposal

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by candinr, May 27, 2020.

  1. candinr

    candinr New Member

    Joined:
    May 27, 2020
    Location:
    Washington
    Because our old sink cracked, we're having to replace it, possibly with a one bowl design. My question is, is there a good way to hook two dishwashers to one drain without a disposal? I've seen one suggestion to maybe, possibly use two wye pieces but our p-trap isn't low enough in the wall for that and I don't want to spend $400 to have it lowered. Also, I read that the drain should be increased to at least 2". From what I can find, there isn't. Thanks!
     
  2. Reach4

    Reach4 Well-Known Member

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    Sep 25, 2013
    Location:
    IL
    Last edited by a moderator: May 27, 2020
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  4. candinr

    candinr New Member

    Joined:
    May 27, 2020
    Location:
    Washington
    We have 2 high loops that works fine. I'm not a professional by any means but what does the air gap have to do with the water draining into one drain vs the 2 like it is now?
     
    Last edited: May 27, 2020
  5. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    The dual air-gap takes two dishwasher drains and combines them into one. The 7/8" hose from the air-gap can then go to a single drain below the sink or to a disposer.

    [​IMG]

    Like this except they also make a dual-air-gap that combines two drains into one.
     
    Last edited: May 27, 2020
  6. candinr

    candinr New Member

    Joined:
    May 27, 2020
    Location:
    Washington
    Thank you for the info guys. I always thought the air gap was just for venting, like you would vent a sink drain. From what I read water should only flow out of the air gap if there is a clog, correct? and if I were to run both dishwashers at the same time (which we rarely do) the water will drain properly? I just want to make sure we're making the right decision if we have to end up with a single bowl sink. I'm making a big deal out of this because we're having to get a custom sink, paid for by our cracked sink's manufacturer (IKEA) because the dimensions are not standard and the sink is no longer available. Thanks again.
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Yes and yes.

    Downside is you have to drill a hole for the air gap if there is not one already. If you are having holes drilled, sometimes people will have a hole for a reverse osmosis or filtered drinking water dispenser. Some even have a hole for a soap dispenser.

    The purpose of the air gap is that if there became a vacuum in the supply pipe, there is no way that drain water could be sucked into the potable water or the dishwasher.
     
  8. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    The air gap is to prevent the sink water from entering the dishwasher.
    A friend of mine had this problem where after a few days the bottom of her dishwasher had dark murky water sitting there. Being a single person household, it would be days before the dishwasher would be used. I added an air-gap and after that her dishwasher stayed clean.
     
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