Best Dishwasher Air Gap Alternatives (How to Avoid It)

Ossiana Tepfenhart
by Ossiana Tepfenhart
Dishwasher air gaps are often required by local building codes, but that’s not always the case. There are a few alternatives to dishwasher air gaps, and the most efficient is a high loop drain hose. Air gaps may be preferable, but let’s take a look at the best dishwasher air gap alternatives.

It never ceases to amaze me how difficult it can be to install a dishwasher in your home. Due to the many design flaws that can come with a dishwasher install, it’s become common practice to install something called an air gap for your dishwasher. An air gap can be pricey, but it can help prevent drainage problems like having water back up into your washer after it’s already been drained. But, are there any ways around this requirement?

Building codes may require you to have a dishwasher air gap since it can interfere with your plumbing and food safety. If you do not have plumbing for an air gap, you can use a “high loop” drain hose configuration or a standpipe as an alternative. Before you get an alternative, check your local codes to ensure your building won’t be due for a repair.

Getting an air gap for your dishwasher is generally the smartest thing to do, but that doesn’t mean that you need to have one. If you want to learn about this particular configuration, keep reading. We’ve done the research so you won’t have to.

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What Is A Dishwasher Air Gap Used For?

To understand why you need an air gap, you need to understand how most dishwasher drainage systems work. With most dishwashers, the water that has finished cleaning up your dishes will be sent right into the plumbing system. The drainage typically works well, but in some cases, you may see backflow.

When backflow occurs, it’s due to a lack of airflow in the piping. This can lead to contaminated water to re-enter the bottom of the dishwasher or even pour into the tap of your sink. A dishwasher air gap is meant to help prevent water from backing up into the dishwasher or to your sink tap after it’s been drained.

Are Dishwasher Air Gaps Always Necessary?

You absolutely do need to have a way to prevent backflow from happening with your dishwasher, and air gaps are generally seen as the most reliable option out there. Most jurisdictions will require you to install an air gap wherever you want to place a dishwasher.

However, you do not need an air gap. There are a small handful of alternatives that you can grab in order to keep your air gap sanitary.

When Are Air Gaps Necessary?

If your piping configuration naturally brings your drain hose above the water level or has a P-trap installed in a way that separates the contaminated water from the safe water, you might not need one. However, most homes require an air gap regardless of the dishwasher model.

What Size Hole Do You Need On An Air Gap?

This can vary based on your setup, but typically, the hole will be 3/4 inch in diameter. The largest it can be is 1 1/4 inch, but with that setup, you can generally assume it’s for a commercial-grade sink. Your best bet is to call a plumber to find out how large your air gap hole needs to be for your plumbing setup.

What Air Gap Alternatives Are Out There?

There aren’t many air gap alternatives that you can choose from, and to a point, it makes sense. Technically, this is an optional fitting for your plumbing. There are other options you can use to help lower the chance of a backflow. We’re going to cover both, and explain how they can work for you.

A High Loop

A high loop is a plumbing piping configuration that brings your drain hose line up above the water level. To create a high loop, you’ll need to install this configuration beneath the base of your sink, near the cabinet. The high loop can be hooked up to your garbage disposal or your drain, depending on your setup.

A Standpipe

Another air gap alternative you might be able to consider is a standpipe. The standpipe is that long, vertical pipe you find right above the P-trap portion of your plumbing. To make this a usable portion of your dishwasher’s ventilation, you will need to make sure that it’s at least 2 inches in diameter.

Most people use standpipes as a way to speed up draining alongside an air gap. However, there’s another way to make sure it helps your washer drain well. To vent your dishwasher and prevent backflow, add a second standpipe under the sink.

Generally speaking, adding a standpipe to your setup is not the best choice. This air gap alternative involves a lot of complicated plumbing maneuvers and also tends to be more expensive than just installing an airpipe. If at all possible, avoid this option if you can. Your under-sink space and your wallet will thank you.

Air Gap Building Codes And Installation Tips: A Quick Guide

We already mentioned a little bit about air gap building codes, and how they can impact your ability to choose an alternative to an air gap. However, it’s important to understand the full role of building codes in your plumbing setup. Here’s what you need to be aware of when you’re planning your dishwasher install:

  • Almost all parts of the United State will have building code mandates regarding air gaps. While there are some areas that won’t require an air gap when you install your dishwasher, it’s fairly safe to assume that you should probably get an air gap. If you are required to have an air gap and don’t have one, you may be fined and asked to redo your plumbing.
  • Some states, such as California, also have requirements for the size of the air gap. Some states require a minimum of one inch, others may require a minimum of two. It’s best to check your local building codes to find out what is necessary in your area.
  • The building codes are there to prevent contamination. All the germs, mold, and grime from your dishwater can pose a serious threat to your health and sanitation. A single moment where your dishwater floods back into your washer or through your sink can lead to days or even weeks of food poisoning. Even if you do not have a code requiring an air gap, you should consider getting one anyway.
  • Generally speaking, most people are going to find an air gap to be the easiest and most affordable solution. It’s extremely unusual for an air gap alternative to be the better option. Before you immediately shy away from an air gap, try to see how much it’d cost to incorporate it. You might be surprised at how much cheaper it is.
  • If you are immune-compromised, then you need to install an air gap. People who are immune-compromised need to beware of the risk of contamination. It only takes one backflow situation to cause your health to plummet.
  • Some jurisdictions will allow you to bypass the air gap requirement with a high loop setup. It’s worth noting that most jurisdictions that have this loophole (including the entire state of California) will not give the same allowance for a standpipe. So the alternative you choose matters just as much as your decision to add it.

How Much Does An Air Gap Cost?

You can pick up an air gap at your local hardware for $10 to $35, depending on how fancy you want your air gap to be. The installation, if you choose to have it done professionally, is usually factored into the overall cost of a dishwasher install.

According to the most recent statistics, you should expect to pay around $50 to $150 for labor and parts in total. If you need to have additional plumbing added into your setup, you may have to pay even more. To save money, it’s best to have your air gap installed as part of a full-service dishwasher installation.

Can You Install An Air Gap Underneath A Counter?

One of the reasons why people don’t want to have air gaps deals with the aesthetic aspect of it. Air gaps are, unfortunately, kind of an eyesore. They have a tendency of breaking the smooth, seamless counter look that many people strive to have. As a result, there are a lot of people who want to know if an air gap might be able to be installed under their counter.

Unfortunately, there isn’t an air gap that fits this bill. While there are engineers working on an under-counter air gap, there isn’t one currently available on the market. If you are dead-set on being able to maintain that seamless look, you might want to look at a high loop or a standpipe.

Do I Need An Air Gap If I Have a Garbage Disposal?

Your garbage disposal is going to run through your sink system as well. Since your air gap is there to help improve the sanitation of your home, you need to have one if you want to install a garbage disposal. In some systems, you can also use a high loop in lieu of an air gap. Unfortunately, this is not always advisable.

Can Air Gaps Do Other Things?

Along with preventing backflow, it’s 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.

It’s worth noting that air gaps that have these types of filters included also tend to need to be replaced from time to time. If you’re 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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Ossiana Tepfenhart
Ossiana Tepfenhart

Ossiana Tepfenhart is an expert writer, focusing on interior design and general home tips. Writing is her life, and it's what she does best. Her interests include art and real estate investments.

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