What states require an air gap?

Author: Ambrose Hand IV  |  Last update: Thursday, October 23, 2025

If you reside in California, Washington, Minnesota, or Hawaii, installing a dishwasher air gap is mandatory per the plumbing code in these regions.

Where is an air gap required?

The use of an air gap is required by plumbing codes for certain plumbing fixtures, such as dishwashers, to prevent the backflow of potentially contaminated water into the clean water supply. If contaminated water backflows, it can cause serious health risks.

Is it necessary to have an air gap?

Air gaps are the most effective means of preventing your drain from contaminating your dishwasher with waste. If you want to protect your dishwasher from flooding with contaminated water, you need an air gap.

What if my sink doesn't have a hole for an air gap?

If your sink lacks an available hole for installing an air gap, a plumber can usually drill an opening where needed.

Is a dishwasher air gap required by code?

Most states even enforce plumbing codes that require dishwasher air gap installation in residential and commercial sinks. If your drain hose is connected to house plumbing lower than 20 inches above subfloor or floor you will need to use an air gap.

Dishwasher Air Gap - Is One Required? | From a Plumbing Inspector

What states require air gaps?

If you reside in California, Washington, Minnesota, or Hawaii, installing a dishwasher air gap is mandatory per the plumbing code in these regions.

Can I use a high loop instead of an air gap?

Both the high loop and air gap methods serve the same purpose of preventing wastewater backflow and are commonly required by building codes to ensure the safe operation of dishwashers. The specific requirements may vary depending on your location and local plumbing codes.

Does a 3 compartment sink need an air gap?

Three compartment sinks should have TWO AIR GAPS.

Do I need an air gap if I have a garbage disposal?

They rely solely on basic physics and gravity to do their job. If you have a garbage disposer and a dishwasher, you will definitely want to use an air gap.

Is high loop for dishwasher legal in California?

Dishwashers Must Have an Air Gap or a High Loop: All dishwashers in California must be connected either through an air gap or by looping the drain hose as high as possible under the countertop. This is to prevent dirty water from the dishwasher from mixing back into the sink or the main water line.

Do modern dishwashers need an air gap?

Do new dishwashers need an air gap? A dishwasher air gap's purpose is to help ensure that the water being used in your appliance is fresh and isn't siphoned out early during a wash cycle. If you live in a state where air gaps are mandated by law, even a new dishwasher will require one to be installed.

What are the two requirements for the air gap?

How Measured: Air gaps shall be measured vertically from the lowest opening of the water supply outlet to either (1) the flood level rim of the fixture or receptor served, or (2) the maximum elevation of the source of contamination.

What is the main disadvantage with the air gap technique?

Limitations of the air-gap technique include potentially increasing patient dose and geometric blurring (unsharpness) 3.

What is the air gap policy?

An air gap involves physically isolating a computer or network from other networks to prevent unauthorized access and data breaches. This method creates a literal "air gap" between the secured network and any other unsecured networks.

Does Texas require an air gap for a dishwasher?

Appliances must have air gaps as required for connections to the sewerage system. Venting must assure a rapid flow of wastewater in the sewage system.

Does Wisconsin require an air gap for a dishwasher?

Air gap requirements vary by state. For example, Wisconsin requires an air gap above or below the sink. The air gap device is usually in the rear left or right corner of the sink. Air gaps installed above the sink can be checked for clogs by removing the cap and checking the screen underneath.

Do dishwashers require a backflow preventer?

In some areas, you are required to have some form of backflow prevention. It will keep your dishwasher running optimally and your dishes in top-top shape.

Can you pour water down an air gap?

Finally, pour hot water down the air gap to deal with any greasy particles. If you can't get any air movement or a clog is still present, you may need to snake it out.

Should a dishwasher drain into the garbage disposal?

Draining into the garbage disposal is pretty much a standard way to connect the dishwasher outlet to drain. There is little or no chance of a clogged drain with this setup.

What are the rules for air gaps?

* An air gap between the water supply inlet and the flood level rim of the plumbing fixture, equipment, or nonfood equipment shall be at least twice the diameter of the water supply inlet and may not be less than 25 mm (1 inch).

What is not allowed in a 3 compartment sink?

To prevent cross-contamination of food utensils when using a 3 compartment sink, follow these food safety practices: Do not use any of the sink compartments for handwashing, preparing food, thawing, or washing dishcloths. Collect all food debris in a receptacle near the washing sink basin.

Which states require a dishwasher air gap?

Which States Require Dishwasher Air Gaps? In California, Washington, Minnesota and Hawaii, a dishwasher air gap is a mandatory residential plumbing procedure.

What happens if the air gap is too small?

If the air-gap is too small there is a possibility that the rotor will hit the stator and, of course, this is to be avoided. However, the benefits of a small gap are a lower magnetization current for the flux density needed. This improves power factor and reduces electrical power losses.

Does a dishwasher need a p-trap?

All plumbing fixtures need to have a trap installed in order to keep sewer gases out of the home. (The only exception is for toilets as they have a built-in trap).

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