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thumbbody 01-19-2013 02:23 PM

Dishwasher airgap backup... errrrr!
So my landlord has had his handyman come to the house to fix an air gap to the dishwasher that is overflowing. It isn't fixed and I'm tired of waiting for this guy.

Here is the issue: When the dishwasher is running and then goes to drain, the air gap backups from the garbage disposal into the air gap and then spills out onto the counter. To rephrase it, water is shooting out from the dishwasher under pressure and the exhaust drain backs up from the garbage disposal and the combined water overflows out the gaps on the air gap onto the counter top. The counter is granite but the underlayment is plywood and leaks through. There is small amounts of water under the sink that is being caught by a bucket and to keep the water contained on the counter I must wrap the air gap with a towel catch the overflow. :furious:

Does anyone have any ideas on what to do?

BC Plumber 01-19-2013 03:12 PM

Can you take a picture from under the sink/the set up of the garborator, and where the dishwasher line passes through the cabinet and ties into the drain?

Gary in WA 01-19-2013 03:51 PM

Not a new install and someone forgot to knock-out the plug in the new GD, or the air-gap reversed?

PS. Welcome to the forums! Plumbing? How did I... wrong door, sorry.

AllanJ 01-19-2013 07:34 PM

The drain is partially clogged.

The drain hose from a dishwasher must fit loosely into whatever it is connected to except the dishwasher drain port of a garbage disposer. Otherwise the dishwasher drain pump can be damaged.

jagans 01-19-2013 10:22 PM

Hi Allen can you elaborate? Not quite sure where you are going with this one, As I have often hooked a DW to a dishwasher tailpiece with hose clamps.

joecaption 01-19-2013 11:13 PM

New one on me to.
Does the sink drain ok?
If not remove the trap under the sink and clean it out.
Make sure to set a bucket to catch the water left in the trap.

md2lgyk 01-20-2013 11:08 AM

This isn't an air gap issue, it's a clogged sink drain issue.

thumbbody 01-20-2013 01:01 PM

Thanks for all the responses. Sorry but the photo isn't linking up. The sink and disposer work just fine. There are no drain issues. No backups. The disposer vents water to the air gap at the sink and then you hear water backing up the out pipe and water overflows to the counter at the air gap. I would assume that the issue is from the air gap to the disposer but the landlords handyman checked that with no issues. Everything worked just fine before.

AllanJ 01-20-2013 01:01 PM


Originally Posted by jagans (Post 1097550)
Hi Allen can you elaborate? Not quite sure where you are going with this one, As I have often hooked a DW to a dishwasher tailpiece with hose clamps.

Correction: The dishwasher hose may be clamped to a tailpiece on a disposer for that purpose. If the drain is obstructed, the water should come up into the sink.

If a dishwasher hose is connected to a standpipe similar to a washing machine drain, it must fit loosely.

thumbbody 01-20-2013 01:07 PM

1 Attachment(s)
Attachment 64030
Here is the photo of the sink. The dishwasher outlet comes from the bottom right corner up to the counter and airgap. Then back down to the disposer. The disposer works fine. Water in the sink drains good. No backups. No clogs that I can when I take it apart.

Is the hose to the disposer too long?

TheEplumber 01-20-2013 01:24 PM

199 Attachment(s)
check the 7/8 hose for kinks and be sure it has no obstructions inside.
If no issue- replace the aircap. Your picture is a typical installation.

fa_f3_20 01-20-2013 11:22 PM

One of three things:
1. The hose from the air gap to the disposal is clogged, kinked internally, or rough inside. That hose is a gravity drain, and it must have a larger internal opening than the hose from the dishwasher, in order to keep up with the dishwasher's drain pump.
2. The two hoses are connected the wrong way around at the air gap. Water will fly out of the air gap if the hose from the dishwasher is connected to the "out" port of the air gap.
3. Going back to what GBR said: As the disposal comes from the factory, there is a piece of plastic that blocks the dishwasher drain connection. It must be knocked out before that connection can be used.

thumbbody 01-21-2013 03:53 AM

I'll look at the hose and make sure the factory plug has been completely removed.

thumbbody 01-23-2013 01:12 PM


I checked the exhaust hose from the air gap and saw that it had an excess of slime. I cleaned out the hose and cleaned out the attachment to the GD. It was blocked but not closed. Running water in the sink I see that some water flow but the hole is blocked by the factory plug. I knocked out the plug, reconnected everything, checked the GD for debris and then tested the dishwasher on 4 min. rinse. Water easily ran through the air gap and visibly running into the GD.

Thanks to all for the advice!:thumbup:

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