Is an Air Gap necessary?

Old 08-09-05, 07:55 AM
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Is an Air Gap necessary?

Just waiting for countertop delivery for my new kitchen and it occurs to me that I didn't ask for a hole to be cut for an air gap for the dishwasher drain. I know they can do this on site, but was wondering if an air gap is really necessary? Is there another under counter option? I do not have a disposal.

Thanks for any help.
Old 08-09-05, 05:08 PM
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If possible, I would suggest drilling a hole for an air gap.

If you do not have a disposal, You could connect the dishwasher drain line to your sink drain by using a dishwasher branch WYE. There are 2 styles: One connects directly to the sink drain and the other connects to the sink tailpiece using a slip joint connection.

If you cannot install an air gap, you should make a loop in the drain line. The loop is necessary for 2 reasons basically the same reason.

* To keep dishwasher drain water from draining back into the d/w
* To prevent siphoning from occurring and drawing waste water into the d/w

Dishwasher manufacturers are finally getting smart and putting a "built-in loop" on the drain line of the dishwasher. Maytag tall tubs are putting in a full height loop. Whirlpool tall tubs, Kitchenaids, Bosch and some GE's are putting in about half-height loops. Perhaps this could solve the"loop" problem altogether and possibly the air gap!

Be sure to loop the drain hose as high as possible to the underside of the countertop, then back down into the disposal/sink drain assembly .

NOTE: This may not be allowed by code in your are, but in some areas, looping is generally accepted without incidents. Call your local plumbing supplier or City for what is permitted.

Hope this helps!
Old 08-09-05, 06:17 PM
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Here is some information that will assist you;

International Residential code 2717.1 & Uniform Plumbing Code 301.1.1


The manner of creating and approved indirect waste varies in the codes. It would then depend upon what code is in effect in your jurisdiction.

The UNIFORM PLUMBING CODE requires ALL dishwashers to have an air Gap fitting above the sink flood level rim
Ref. UPC 807.4

The INERTERNATIONAL RESIDENTIAL CODE allows alternate methods of creating the required Indirect Waste.

Drain line must be secured in a high loop as high as possible under the counter the drop down to the point of connection to the drain Ref. IRC 2717.2.3
1. May discharge into a Garbage Disposal inlet port.
2. May discharge into a Wye tailpiece (the tailpiece must be in a vertical position)
3.May dishcharge into a trapped fixture
REF. IRC 2717.2.3

Many localities that are under the INTERNATIONAL RESIDENTIAL CODE have local additional code requirements that make the Air Gap fitting mandatory.

The best solution to your question is to contact your local code authority and find out what is required in your jurisdiction.

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