Dish Washer, is an air gap still a requirement?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by rap, Feb 7, 2012.

  1. rap

    rap New Member

    Messages:
    63
    Location:
    california
    I've noticed in another place a claim that there is now, in many states, no code requirement for using an air gap with a dish washer drain. The only requirement now is for a high-loop in the D/W drain pipe. Any comments?
  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,798
    Location:
    Bothell, Washington
    California uses the UPC code, which is one of the codes that requires the air gap fitting.
    The best thing would be to call your local inspection office and see what they want.

    We use the air gap in Washington State.

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    Last edited: Nov 19, 2012
  3. rap

    rap New Member

    Messages:
    63
    Location:
    california
    Thank you Terry.
  4. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,073
    Location:
    Maine
    I live in Maine which is UPC and an air gap is required
    In NH (just over the boarder) which is IPC only a high loop is required.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,820
    Location:
    New England
    The safest connection is an air gap, whether required or not. It's up to you to decide, if you have the choice.
  6. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,073
    Location:
    Maine
    Modern dishwashers will usually have the high loop already installed on the appliance itself so running another under the sink cabinet effectively double traps the line which is not a good thing.
  7. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    I installed my dishwasher with a high loop. I heard those sink top air gaps will fail and flood yo kitchen man. Thats a no go. Plus it looks like crap and takes up a hole in the sink. LOL
    I know they have a purpose but I'll take my chances. The last thing I'm worried about is the perfect storm happening and I get sick from how my dishwasher is hooked up.

    I worry more when I go out to dinner. I've worked in all those kitchens every plumber on this forum knows what I'm talkin bout.

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    Last edited by a moderator: Mar 8, 2012
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,292
    Location:
    Cave Creek, Arizona
    quote; running another under the sink cabinet effectively double traps the line which is not a good thing.

    It is a pumped discharge and therefore it can have as many "traps" as you want to use. Whether an air gap is required or not is usually a local issue.
  9. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,073
    Location:
    Maine
    It is indeed a pumped fixture but when you double trap it, water stays in the low part of the drain hose which is not a good thing if you can avoid it
  10. davianmcllm

    davianmcllm New Member

    Messages:
    1
    Location:
    Douglasville, GA
    First, I want to make sure I'm using the correct terminology.
    The little device that is connected to your dishwasher that sits inline with your faucet, etc. on top of your sink. Usually it has a little metal(or plastic covered with metal) cap on it and it let's air in.
    Second, I understand now that the CA code requires the something, but is there a way to do it differently so that you don't need that ugly little cap, etc. on your sink?
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,820
    Location:
    New England
    If your local code requires one, you need one. Haven't really looked into styles of what's available. It doesn't have to be installed on the sink deck, it can be anywhere on the counter but that requires an additional hole.
  12. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    But, THAT does open you up to the potential flood in the event of a backup. That is not something that should ever happen...but we know that things sometimes DO happen.
  13. Terry

    Terry Administrator Staff Member

    Messages:
    14,798
    Location:
    Bothell, Washington
    And yet not all modern dishwashers have that. Sue's home had a new kitchen remodel, stainless appliances including dishwasher. She often had murky water in the dishwasher, sometimes enough to spill out the front when the door was opened. She had no "high loop" and no "air gap".

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    The dishwasher was installed to the disposal, and the disposal had been plumbed without a p-trap. Wow! A complete kitchen remodel and they installed the new granite countertops with stainless undermounts without an air gap or a p-trap. Pretty gross!

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    I went ahead and pulled the old antique disposer and installed a quiet Evolution disposer. Moved the drain in the wall and made sure that the disposer was now trapped before making it's way down the drain. The dishwasher now drains with an air gap on the counter top, and the bottom of the dishwasher is now clean, not murky. While I was at it, I added a frostfree faucet for watering outside to the piping under the sink.
    It's always better with an air gap!

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