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How To Install Dishwasher Air Gap To A Garbage Disposal?

You just can’t beat the convenience of having both a dishwasher and garbage disposal in your kitchen. Unfortunately, you have to take some precautions to prevent accidents and protect yourself from liability when these two appliances are combined. 

Air gaps prevent backflow from the plumbing system into the dishwasher. Backflow can cause contaminated water to enter your dishwasher. This can be prevented by installing an air gap between the dishwasher and the plumbing.

The plumbing code requires homeowners to install an air gap with their dishwasher. So, you cannot overlook this vital setup because of code compliance or if you want to prevent your clean water supply from contamination. Often, plumbers install an air gap, but you can install it yourself fairly easily by following the directions given in this article.

What is an air gap?

An air gap is a fitting through which a dishwasher outlet is connected to a garbage disposal. This fitting is mounted on the kitchen sink and it has two hoses underneath each connecting to a dishwasher and a garbage disposal. An air gap increases the vertical distance or gap between the dishwasher and the garbage disposal thus preventing any backflow from the garbage disposal from entering the dishwasher.

Air gaps fitted on a countertop
Air gaps fitted on a countertop

How does a dishwasher air gap work?

An air gap has two branches of hose. One branch goes upwards, connecting the dishwasher to the air gap, while the other runs down from the air gap towards the garbage disposal.

Kraus KAG-1SFS Dishwasher Air Gap, Spot Free Stainless Steel

The air gap head goes above the countertop while both the branches are beneath the counter. The head consists of a vertical air gap with holes. If there is any backflow from the garbage disposal, these holes act as an escape route for waste waster thus preventing wastewater from entering the dishwasher. So, if you see wastewater gushing out of the air gap, it means that there is a blockage in the plumbing system that must be removed.

dishwasher drains water at air gap.

How to install air gap to garbage disposal?

Having an air gap helps avoid costly plumbing repairs and damage to your dishwasher by reducing the possibility of drain backups caused by clogged garbage disposals. So, if you’re looking to install an air gap between your dishwasher and garbage disposal, follow these simple steps!

Step 1: Look for a precut hole on your counter

Many countertops already have a precut hole near the base of the faucet. Usually, a flat cap is covering this hole. When you locate this cap, pry it open using a flat-blade screwdriver or remove the lock nut underneath it if has one. If you don’t find this precut hole, you will have to drill a hole in the countertop for the air gap.

Use an electric drill and hole saw to drill a hole near the sink’s rim, so the air gap has enough room if the tubes overflow. If you are not comfortable using a drill yourself, I will suggest hiring a professional, so you don’t end up damaging your countertop. 

Step 2: Connect the dishwasher drain hose to the air gap

The small leg of the air gap should connect to the dishwasher drain hose. Use stainless steel hose clamps to tightly attach the 5/8” tube to the 5/8” leg of the air gap.

Step 3: Connect the air gap to garbage disposal

Cut a 7/8” length of tubing to fit between the air gap and your garbage disposal. Connect this tubing to the dishwasher outlet of the garbage disposal. If the dishwasher was not connected to the garbage disposal previously, this outlet will have a plug inside it which needs to be removed before connecting it to the air gap. Secure the connections using a suitable metal clamp.

Step 4: Insert the air gap through the precut hole in the countertop

The air gap has a cover on its head. Remove it before pushing the air gap through the countertop hole from below. Lastly, ensure to attach the air gap securely to the counter using plumbing fittings. Then put the cover back on the air gap head.

Step 5: Run the dishwasher to ensure secure connections

Running the dishwasher on a complete cycle will ensure that the air gap has been fitted perfectly without leaking through the pipe connections. If you don’t find any dripping signs, it means you have successfully installed an air gap to your garbage disposal.

Given below is a video showing the detailed installation of an air gap between a garbage disposal and a dishwasher.

Air gap installation between dishwasher and garbage disposal

Do I need a dishwasher air gap?

Whether or not you need an air gap in your kitchen can depend on several factors. You may need to install an air gap with your dishwasher to comply with the plumbing code of your area of residence. Moreover, installing an air gap can be an essential precaution to keep your family safe. It prevents sewage from backing up into your dishwasher and protects your entire family from harmful contaminants that can cause serious illness.

Wrap up

As you can see, an air gap is an essential component of a functioning dishwasher. It is a necessary safety precaution that ensures waste water doesn’t seep back into your sink pipes or dishwasher. Installing one is easy, and anyone with a bit of know-how and common sense can do it. 

It’s an important fitting that can save you time and money in the maintenance of the dishwasher down the road. So, the next time you’re considering installing a dishwasher, think about adding an air gap to keep your home safe from potential plumbing and health issues.

My name is Thomas Anderson, author of DisposalQA. I have 15 years experience working as a plumber in CA, and this is where I answer common questions about garbage disposals.