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Thread: water coming out of dishwasher air gap

  1. #1
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    water coming out of dishwasher air gap

    At a friend's house, water comes out of the dishwasher air gap on the sink when the dishwasher drains. There are no clogs in the drain line from the air gap to the garbage disposal. The line is not kinked. The air gap itself is not clogged. The input hole to the dishwasher is not clogged. (We took the air gap and the drain line off and made sure they were clear before re-installing them.) Is it possible that the dishwasher just drains too fast for the air gap system? Do dishwashers typically have an adjustment that sets how fast they drain?

  2. #2
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    Can you post a photo of the plumbing under the sink that shows the dishwasher connections? Also, please explain what you mean by "air gap". This link shows some common errors made with dishwasher plumbing.
    Lee Schierer
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  3. #3
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    Probably a problem with the drain line past the trap. Something is causing it to drain too slowly.

    I expect you're talking about an automatic vent. That is not the problem, unless it was installed too low. Water should drain fast enough to flow away before it can rise that high.

  4. #4
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    Is there a disposal installed? They can cause a blocked pipe due to grease. Take the P pipe off and check.

  5. #5
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    Quote Originally Posted by Lee Schierer View Post
    Also, please explain what you mean by "air gap". This link shows some common errors made with dishwasher plumbing.
    DIshwasher air gap: https://www.tampaapplianceparts.com/...asher-air-gap/

    ( The link you gave has a section about dishwasher air gaps.)

  6. #6
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    Quote Originally Posted by Myk Rian View Post
    Is there a disposal installed? They can cause a blocked pipe due to grease. Take the P pipe off and check.
    Yes there is a garbage disposal and the drain line from the air gap goes into the disposal. I can look into the disposal while the dishwasher is draining and see water enter the disposal. Water does not build up in the disposal.

  7. #7
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    Disconnect the line from the air gap to the disposal and let it drain into a 5 gallon bucket. Run a cycle and see if the problem recurs. That will tell you if the problem is ahead of the disposal or after. This problem is almost always clog related. Most air gaps have a smaller inlet and a larger outlet. Make sure the DW isn't connected to the outlet side. And make sure you don't have the drain stopper in place on the sink drain when you run the DW; that can slow draining enough to cause the problem.

    If all else fails, see if an air gap is really required by code in your area. A lot of areas just require the drain hose to be run up high under the cabinet and then down to the disposal. Maybe you can just do away the air gap.
    --Certainty is the refuge of a small mind--

  8. #8
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    So there should be two hoses going into the air gap cap. There are specially made little brushes to clear out any clog, either on the dishwasher side or the disposal side. A clog on either side will cause the gap to leak. This is going to sound disgusting but I just spray the gap cap (with the cover off) with some bleach solution, let it sit for a couple of minutes, rinse it off and dry it, then put my lips to the gap cap and blow to clear the line. Works every time.
    Regards,

    Tom

  9. #9
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    I bought a house recently and had the same problem. Turned out that no one removed the dishwasher plug in the side of the disposal when they installed it.....at least 10 years prior.
    Rick Potter

    DIY journeyman,
    FWW wannabe.
    AKA Village Idiot.

  10. #10
    someone help me understand:

    airgap.jpg
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  11. #11
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    It doesn't, the purpose of the airgap is to prevent you from pressurising the drain system.......Regards, Rod.

  12. #12
    Just ditch the air gap. They are an old tech, modern diswhashers can push far more than most airgaps were ever designed for. A through counter air gap is like 1970 era. If your seeing water out of the air gap and not coming up through the disposal its either drain hose size or the airgap just cant handle the output of a modern dishwasher. Dumping into a disposal all your post flow is going to be gravity through the disposal and down the drain so if there is a real issue and your DW drain hose is not plugged/too small, youd be seeing DW discharge in the basin with the disposal.

    Rip the airgap out and plug the hole.

  13. #13
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    clearing the air gap itself starts at about the 1:20 mark

    Air Gap Leaking Water? Easy Fix Guaranteed! - Bing video


    my take on why an air gap is recommeded is to stop potential back siphoning from the sink\disposal\waste line
    Last edited by Mike Soaper; 12-01-2021 at 7:48 PM.
    Hobbyist woodworker
    Maryland

  14. #14
    Quote Originally Posted by Mark Bolton View Post
    Just ditch the air gap. They are an old tech, modern diswhashers can push far more than most airgaps were ever designed for. A through counter air gap is like 1970 era. If your seeing water out of the air gap and not coming up through the disposal its either drain hose size or the airgap just cant handle the output of a modern dishwasher. Dumping into a disposal all your post flow is going to be gravity through the disposal and down the drain so if there is a real issue and your DW drain hose is not plugged/too small, youd be seeing DW discharge in the basin with the disposal.

    Rip the airgap out and plug the hole.
    Assuming their local code doesn't require an air gap.

  15. #15
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    Quote Originally Posted by Kev Williams View Post
    someone help me understand:

    airgap.jpg
    The air gap won't prevent the water you highlighted from flowing back into the dishwasher. It's purpose is to prevent water than's in the sink trap (or garbage disposal) from siphoning back into the dishwasher.

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