• Howard Gallagher

What Is A Dishwasher Air Gap?

Updated: Jun 14

You have a brand new dishwasher. You may have gotten a suggestion from a plumber to install an air gap alongside your new unit. This is a vital small fixture that is placed above your counter top. An air gap is the most effective method to protect your dishwasher from backflow. Clogged piping can send dirty water from your drain into your dishwasher. Here is everything you need to know about Dishwasher air gaps.

Dishwasher Air Gap Basics


A dishwasher air gap is usually a small metal cylinder near your sink faucet with a few holes in it. The main purpose of this part is to prevent dirty water from draining back into your dishwasher. In event of your sink drain being clogged the water won’t hit the faucet outlet due to the air gap. Used water and clean water shouldn’t mix. This prevents the spread of harmful bacteria. In certain states instead of a cylinder a high loop is installed. A high loop is installed under the sink through the garbage disposal. The purpose of the high loop is so that there is enough pressure due to water weight to close the check valve at the base of the drain pump. Certain manufacturers like GE and Kenmore suggest installing a high loop to prevent water pooling. The high loop method is not as reliable as an air gap, but it can help to prevent contaminated water from being drawn back into the dishwasher. Instead of an air gap, some handymen has installed a check valve in the dishwasher drain hose below the sink. However this doesn’t comply with some building codes. You should check your dishwasher air gap on a regular basis. This is to ensure your dishwasher, sink and pipes are working properly.

Backflow Issues


Backflow is the unwanted reversal of water flow. Dirty and contaminated water will go back into the clean water supply. This is also known as a cross connection which can also cause fluctuations in water pressure. If this issue is not fixed then back flow can siphon into your appliances like dishwasher and garbage disposal. An air gap leak is when your drainage pipes are leaked and need to be cleaned out. A key indicator of this is your dishwasher draining slowly. Remove the hose that connects your air gap to your sink. Clean it out with a plumbing snake or hanger. Reconnect the hose to the air gap with one end point to the sink. Test your dishwasher with a rinse cycle. Observe your hose to see any obvious leaks.

Are Dishwasher Air Gaps Necessary?


Air gaps, check valves and high loops are efficient devices to prevent back flow from affecting your dishwasher. There are required in many parts of the country. In order to sell a home in certain places, a home inspector will require you to install an air gap. Many commercial sink possess an air gap. A plumber installing a new dishwasher will require you to have an air gap connection. If you do forgo an air gap, your house will not be up to code. If you were to ever attempt to sell your house, the home inspector would require you to install an air gap.

Dishwasher Maintenance


Maintaining your dishwasher can prevent serious issues down the line. Even if you have an air gap installed. The unit needs to be maintained to prevent clogged pipes. This means soaking the dishwasher filter, clean the spinning arms and clean the drain.

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