Dishwasher Drain Hookup Question.....

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Galaxieman, Aug 6, 2014.

  1. Galaxieman

    Galaxieman New Member

    Messages:
    6
    Location:
    South Florida
    I am in the middle of a kitchen remodel.

    The old setup:
    Old sink was a dual bowl type. There are two 1 1/2 inch drain connections in the wall (to my septic tank). The sink’s right bowl drain was connected only to the right sewer connection through a normal trap with 1 1/2 inch PVC. The sink’s left bowl was connected to the other sewer connection with the same size PVC but also had the common WYE pipe under the sink drain that drained the dishwasher.

    The new setup:
    Will only have a single bowl sink. I plan to connect that drain to the same right sewer connection just like the old right bowl on the old setup (1 1/2 inch PVC and a trap). I would like to use the other sewer connection JUST for the dishwasher drain.


    Question:

    Is it possible?

    How do I ‘correctly’ hookup the dishwasher directly to a sewer connection?

    I know I will need a trap, but what else?


    Thanks for your help....
  2. Galaxieman

    Galaxieman New Member

    Messages:
    6
    Location:
    South Florida
    I guess, since I did not get any response, that my question was too dumb or maybe not clear enough....

    Let me try to make it a little clearer with a picture....

    [​IMG]

    This is a shot of my kitchen sink plumbing currently. We have the dishwasher on the other side of the wall in a ‘temporary’ kitchen. The drain is hooked up just as it was when the dual bowl sink was there. It works fine like this, but I realize that I cannot leave it like this.

    Can I block off the top of the WYE and simply ‘drive’ the dishwasher directly trough the trap, without any ‘venting’? If I need venting what is the correct way to do so?
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,317
    Location:
    New England
    The DW needs to be before the trap, and the easiest way to install it is like it is now. Note, though, that depending on where you live, they may require a DW air gap, and not just a high loop. This can be an issue when remodeling...things that get changed need to meet current codes, where the 'old' way may have worked for ages. There's a real safety issue with a DW that an air gap solves. IF the drain does get clogged, you can put sewage into the DW, and not know it, ending up with dangerous dishes and utensils. That is probably easier to make happen if you have a garbage disposal, since that acts like a pump, but it can still happen since you can't get your high loop above the flood rim of the sink.
  4. Galaxieman

    Galaxieman New Member

    Messages:
    6
    Location:
    South Florida
    Thanks for your response 'jadnashua'....

    you wrote: "The DW needs to be before the trap, and the easiest way to install it is like it is now."

    I understand that the DW drain hookup needs to be before the trap. The problem with the install as 'it is now' is that the top of the DW tailpiece, which used to hook to the second sink bowl, is open. I don't like it open. Assuming I have a high loop in the DW line is there any problem with completely blocking off the top of the tailpiece where it used to connect to the sink? It seems to me that blocking it off would be no different than my old setup when the sink stopper was inserted into the bowl above that tailpiece.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,317
    Location:
    New England
    Use a new downpipe on the new sink with the tap for the DW. You can cap anything that you do not tear out if it is no longer needed. I would not leave that old downpipe and just cap it and I do not know if it would be okay.
  6. SHR

    SHR Member

    Messages:
    139
    Location:
    Minnesota
    Easy. Just take the drain pipe tubing from the current left-side and move it to the right side. You may need an 1 1/2" tubular extention to make it work.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    You have "tunnel vision" about the drain. Connect the dishwasher to the sink drain using the same parts you have there. DO NOT connect the dishwasher directly to the drain system with its own trap.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    You have "tunnel vision" about the drain. Connect the dishwasher to the sink drain using the same parts you have there. DO NOT connect the dishwasher directly to the drain system with its own trap.
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