What Is A Dishwasher Air Gap
The dishwasher air gap is critical because it prevents sewage from flowing back into the dishwasher. If your sewage line backs up, the water will drain up through the air gap into your sink rather than back into your dishwasher. Air gaps for dishwashers are the most effective anti-backflow devices and should not be substituted with another method.
How Much Does It Cost To Fix A Broken Dishwasher Motor
Dishwasher Motor Repair Costs Dishwasher motor repair costs range from $200 to $500 depending on the problem and type of motor. Motors are one of the most important and expensive components in dishwashers, supplying power and water to the spray arms. If your dishwasher is not working properly, there may be a problem with the motor.
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Is An Air Gap Required For Dishwashers In California
Air gaps arent required for dishwashers in every single state, but many of them do. One such state is California where you must install your dishwashers with an air gap. Follow along as we explore how you can install an air gap in your dishwasher to comply with California state law.
After enduring so many nights of doing the dishes, youve finally been able to save up to get a new dishwasher. Its a cause for celebration! Adding that new dishwasher to your home kitchen is going to make a huge difference.
Make sure you check out the laws in your area before proceeding with installation though. In California for instance, homeowners have to abide by certain guidelines if they want to install a dishwasher. One of those rules pertains specifically to air gaps.
Installing an air gap is a necessity if you want to use a home dishwasher in California. According to California law, the air gap must be approved and it should also be installed on the discharge side. The air gap should also be installed with its flood-level marking at or above the sinks flood level.
As a homeowner, you need to be more aware of local laws regarding new appliances you want to use. In this article, well focus specifically on dishwashers and the need to include air gaps. Read on to learn more about this important topic.
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Why Is A Dishwasher Air Gap Important
The main purpose of a dishwasher air gap is to prevent wastewater from leaking into your clean water supply. Even if some consider them an eyesore, theres no arguing against their practical importance.
Its common for a high loop to get used as an alternative to an air gap. However, some plumbing codes require dishwasher air gaps because theyre the one approach guaranteed to effectively separate clean and contaminated water.
Is The Dishwasher Air Gap Required By Code

New plumbing codes concerning air gaps in dishwashers were adopted by some states in the United States in 2016. Following the code, it is prohibited to install a dishwasher without a proper air gap. But the regulations have not yet been implemented everywhere.
As of now, new plumbing codes are mandatory in California, Florida, Texas, Nevada, Washington, and New Jersey. The air gap plumbing code is also being rolled out to other states.
You should use the air gap not only to comply with the law but also to maintain the hygiene of your dishwasher, sink, and dish. It is very difficult to open and clean a clogged pipe manually. The use of air gaps reduces the chances of clogging.
In contrast, if it becomes clogged, you can easily clean it.
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How To Make Dishwasher Drain Hose Connections
Aaron Stickley is a licensed plumber with 15 years of experience in commercial, new residential plumbing, and residential service and repair. He started his own residential service and repair plumbing business. Aaron’s articles about plumbing on The Spruce span four years.
The Spruce / Kevin Norris
- Working Time: 1 hr, 30 mins
- Total Time: 1 hr, 30 mins
- Skill Level: Intermediate
- Estimated Cost: $15 to 25
As part of the overall installation of a dishwasher, hooking up the drain is usually pretty easy, but it’s important to understand the different options when doing so, with or without a garbage disposal.
If you are removing a dishwasher and replacing it with a new one, it is usually easiest to simply copy the same drain hookups that were used on the old dishwasher. But if you are adding a dishwasher for the first time, you may need to install a special drain fitting known as a Y-branch tailpiece to give the dirty water a place to flow into your drain system.
The different drain variations you may encounter include:
- Drain line connected through an air gap to the garbage disposal
- Drain line connected through an air gap directly to the drain
- Drain line configured in a “high loop” to the garbage disposal
- Drain line configured in a “high loop” directly to the drain
What Is A Dishwasher/sink Air Gap
If you are installing a dishwasher or already have one but without an air gap, you need to install one. Not only is a dishwasher air gap required by code, it is the most effective way of preventing backflow and contamination of your dishwasher when the drain line clogs.
Before air gaps became common, dishwashers were plumbed by looping the drain hose high underneath the countertop. That method has little success in preventing wastewater backflow to the dishwasher. More on this later on in this post.
If water from your sink is going into the dishwasher, you have a clogged sink drain line or garbage disposal. To fix this problem, you will need to unclog the sink drain and install an air gap to prevent the same from happening in future.
But what is a dishwasher air gap and how does it work? Do you even need one?
A sink/dishwasher air gap is a fitting installed between the dishwasher drain hose and the sink drain line/garbage disposal to prevent backflow, contamination and an overflowing dishwasher.
The top of the air gap has a finished cap and pops 2 inches above the sinks rim. In case of a clogged drain line, the air gap prevents the wastewater from being siphoned back to the dishwasher.
One thing to remember is that the dishwasher, garbage disposal and sink share the same drain line. This means that if there is a problem with one of the 3, all the others will be affected. That is the reason you will see water backing up to your sink when running a dishwasher.
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What Is The Best Way To Install A Dishwasher Washing Machine
Any washing machine or dishwasher manual should state the minimum distance between the machine and the cold water tank. It is better to place the device on an outside wall. This means you dont have to run the drain hose along the inner wall of your house. Washing machines and dishwashers must be placed on a firm, level surface.
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How A Dishwasher Air Gap Works
The dishwasher air gap keeps dirty drain water away from your clean water supply. Air gaps have two hoses: an in hose on the right side where water gets forced upward by the dishwasher pump and an out hose that drains water using gravity. Some dishwasher units automatically come with an air gap but not all do.
For a dishwasher air gap to work efficiently, the out hose should alwaysbe larger than the in hose. Otherwise, it could lead to drainage issues.
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Secure The Drain Hose
Loosen, but do not remove, the screw on the hose clamp that holds the dishwasher drain hose to either the garbage disposal or the sink drain. Pull the drain hose off the sink drain or garbage disposal and slide it over the smaller of the two legs on the air gap. Secure the dishwasher drain hose to the air gap by tightening the hose clamp screw.
Cut a length of 7/8-inch inside-diameter drain hose to fit between the air gap and the sink drain or the garbage disposal. Slide a hose clamp onto each end of the new drain line. Attach one end of the drain line to the remaining leg on the air gap and tighten the hose clamp screw to hold it in place. Attach the remaining end of the drain line to either the sink drain or garbage disposal and secure it with the remaining hose clamp.
What Are The Dishwasher Air Gap Options
There are two primary ways that a homeowner or contractor can accommodate the building codes and prevent backup of dirty water into clean areas or systems.
One method is by purchasing and installing a dishwasher air gap fitting. This fitting usually attaches to the sink or the counter, and it connects to the dishwasher hose. Designed for the safety of the homes residents, the device creates a pressure break that blocks filthy water from seeping back into the dishwasher and ruining the clean dishes. The air gap fitting links either to the garbage disposal or to the drain itself. Its a basic yet useful preventative measure.
However, if youd prefer not to use that fitting, there is a dishwasher air gap alternative. You can make a high loop, a unique configuration of the drain hose that takes the line up above the water level. The loop is installed beneath the sink base in the cabinet. Its usually hooked up to the drain, but it can also be linked to the garbage disposal.
There is also one more option standpipe. The vertical pipe located directly above the P-trap is called the standpipe. This pipe needs to be at least 2-inches in diameter and vented regularly. Standpipes are commonly used to quickly drain the water in washing machines between the fill and drain cycles. However, some homeowners incorporate them under their sink as an alternative to installing an air gap.
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How To Install Dishwasher Air Gap From Scratch
Heres how you can install the dishwasher air gap from scratch.
Can Air Gaps Do Other Things

Along with preventing backflow, its possible to have an air gap that does double-duty as a water filter. Currently, you can find air gaps that have reverse-osmosis filters, specialty ionizers, and more. If you have a need for extra water filtration, it may make sense to have an air gap that can filter out impurities.
Its worth noting that air gaps that have these types of filters included also tend to need to be replaced from time to time. If youre willing to make that commitment, it might be worth the effort. Otherwise, you may be better off installing a Brita filter or ZeroWater filter instead.
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Sink Drain Or Garbage Disposal Is Clogged
When the garbage disposal or kitchen sink drain is clogged, it means wastewater from the sink cannot flow out into the sewer lines. Where will the wastewater go to?
If you do not have an air gap, water will flow back to the dishwasher via the drain hose. Actually, if the drain hose is looped high, as more water enters the loop the stronger a siphon is created.
When enough water has filled the loop, the dishwasher drain hose will siphon water out of the sink and dump it inside the dishwasher. This is why people with no air gaps have water backing up into the dishwasher when draining a sink.
With a dishwasher air gap already installed, things are a little different. Why? Because there is a gap of air between the sink drain line/garbage disposal and the dishwasher.
The air gap obeys the law of science which states that Water cannot siphon back through an unpressurized gap of air. This means that wastewater inside your sink or garbage disposal cannot be siphoned /sucked into the dishwasher drain hose.
Dishwasher High Drain Loops / Air
Dishwashers, if present, are a permanent fixture that will get inspected and tested in a standard Texas home inspection. What Ive found to be the most prevalent defciency with dishwashers doesnt actually have anything to do with the dishwasher itself, but its drain hose.
All of the dishwasher manufacturers require some method of air-gap or back-flow prevention to be used to prevent dirty dishwater from washing back into the dishwasher barrel. Back-flow prevention isnt quite the exact term but this concept of an air-gap is quite prevalent in plumbing and the idea is to stop or limit the potential syphoning of water to places it shouldnt go. Imagine if water was to buildup in your food waste disposer and then flow backwards into your clean dishes sitting in the dishwasher. That would be gross!
There are a couple ways to create this air-gap. One of them is to install a fitting near the top of the sink / countertop, appropriately named an air-gap. The dishwasher drain hose connects to the air-gap and another hose leads from the air-gap to the drain / garbage disposal, and the air-gap creates a break in the line. This fitting occupies the space that you would normally use for something like a soap dispenser and is generally unsightly, so its pretty rare to see these things anymore.
The much more practical and easy-to-install method is a dishwasher drain loop.
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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 dont 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 sinks 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 dont end up damaging your countertop.
How To Implement A Dishwasher Air Gap Alternative
If youre planning to use the high loop method, you need to check your local building codes first, just to make sure that your area permits the dishwasher air gap alternative rather than the actual fitting.
It should measure at least 32 above the floor.
If youre going to connect the high loop straight to the drain, youll need to draw out as much extra length from the existing drain line as you can to make the loop. Arch it up under the sink, against the underside of the sink.
Attach a strap or pin to hold this loop in place. Then, grab the end of the drain line leading from the dishwasher. Youll need to link the lines with a Y-branch piece and a hose clamp. Make sure the T-branch tailpiece you use is the perfect size match for the drain hose.
For connecting the high loop to the garbage disposal, the process is similar. Again, make sure you have as much drain line slack as you can get, and strap the drain hose up high beneath the sink. Hose clamps are sufficient for connecting the dishwashers drainage line right into the garbage disposal.
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What Does The Dishwasher Air Gap Mean
The dishwasher air gap is not popular, but it is now getting attention. Fortunately, it plays a crucial role in operating the dishwasher easily and keeping your familys health safe. By putting it in simple words, it is an essential element in the dishwasher that prevents contaminated water from backing up into the dishwasher. Thus, it provides you with clean, fresh, and healthy dishes to serve.
For instance, when you are using a dishwasher and dishes go into the wash cycle, the last it throws out dirty water from the garbage disposal pipe. Thus, you expect a good result in having clean and fresh dishes, but it happens only when there is an air gap since it does not back up the dirty water into the dishwasher to clean dishes. Instead, it takes clean water all time to clean dishes.
From a technical point of view, a dishwasher air gap is a perfect way to give the dishwasher a perfect understanding to throw out dirty water, and it wont supply back. This little gap allows the water to flow without contamination.
Maintenance Clean The Filter
The filter sits at the base of the inside of the dishwasher and traps large food particles that might otherwise get into the mechanisms and cause significant issues. Most manufacturers recommend cleaning it once a month, and its really worth it to follow that schedule. A dirty filter can cause noxious odors, and its hard to believe your dishes are actually clean when they come out of a stinky unit. Cleaning the filter isnt hard its designed to be clipped in and out. Simply take it out and give it a good clean with hot, soapy water. If its been damaged, its probably replaceable.
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