Proper Drain / vent setup for Dish Washer

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by jamiedolan, Mar 6, 2009.

  1. jamiedolan

    jamiedolan New Member

    Messages:
    28
    Location:
    Wisconsin
    HI guys;

    I've made a few posts here in the electrical forum, new to the plumbing area. I hope you can help me out with a question on the drain setup for my new kitchen. Thanks much in advance.

    I am doing a full gut and remodel on my kitchen. The main counter will be a U shape design, there will be a corner cabinet between main sink and the dishwasher. The dishwasher will be on a peninsula.

    I have never installed a dishwasher before that was not directly connected to the sink / dishwasher.

    My plan is to install a separate 1.5" PVC drain pipe to the dishwasher. My confusion is as to what the best way is to connect the dishwasher to this pipe is (normally I would connect the 1"-ish dishwasher drain hose to the spot on the disposal, is there an adapter or fitting I should use when connecting directly to PVC) , and it's venting requirements (It will be beyond 3.5' from the vent). Do I use a AAV or is no vent required? (or do I need to try and figure out how to get this into the venting system?

    Thanks very much,

    Jamie
  2. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    All traps must be vented.
  3. Terry

    Terry Administrator Staff Member

    Messages:
    15,001
    Location:
    Bothell, Washington
    You may want to run the dishwasher drain back to the kitchen sink plumbing with a longer flex line.
    Depending on your local area,
    You may need to run that drain high at some point, and then to the disposer or a seperate trap,
    Or you may need to use an air gap for the dishwasher.

    The waste on the kitchen sink is 2" below the vent.
    The the traparm, trap and vent can be 1-1/2"

    [​IMG]
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,623
    Location:
    Cave Creek, Arizona
    Dw

    BEcause of the requirements to connect the DW to the drain system there is almost no way to do it without creating a potential overflow/flood location at the DW. Better is to use a long hose and connect it to the disposer. Whether you need an air gap or not depends on your local regulations.
  5. jamiedolan

    jamiedolan New Member

    Messages:
    28
    Location:
    Wisconsin
    Thank you both for your responses. If I route the drain hose under the cabinet base to the main sink base, it won't really be a very long run.

    If I need a couple extra feet on that dishwasher hose to reach to the disposal, can I just replace the dishwasher hose with some of that flexible reinforced rubber hose?

    Last time I had checked they didn't require the air gap for the dishwasher here, it could go right to the disposal, is there any reason to use the air gap if it isn't required?

    Thanks again
    Jamie
  6. msgale

    msgale New Member

    Messages:
    90
    Location:
    Ohio
    air gap benefit

    once while visiting a friend's, their disposer clogged.
    Their air-gap-less set up meant that they had dirty sink water siphoning the wrong way down the dishwasher exit hose, to dishwasher, then to floor, and rest of house.

    Not at all pretty.

    From that day on, i was convinced of air gap cost-benfit ratio was excellent.
  7. jamiedolan

    jamiedolan New Member

    Messages:
    28
    Location:
    Wisconsin
    Ok, will do. Do I need the Air gap to be exposed just above the sink as was shown in a photo here, or can the same thing be accomplished just below the sink where it will not be exposed?

    Thanks very much
    Jamie
  8. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Air gaps are made to be mounted up on the sink. You can get one that has a built in soap dispenser. so it would be more visual pleasing.

    [​IMG]
  9. jamiedolan

    jamiedolan New Member

    Messages:
    28
    Location:
    Wisconsin
    Cool, perfect solution, I'll hunt one of those down and install it. Do you think I am ok making the dishwasher hose a few feet longer if necessary?
    Thanks
    Jamie
  10. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    It wont hurt I seen them pretty long due to the location of the dishwasher to the sink.
  11. jamiedolan

    jamiedolan New Member

    Messages:
    28
    Location:
    Wisconsin


    Excellent. Thanks again for helping me get this figured out!
    jamie
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