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Dishwasher Air Gap Alternatives

The air gap is a requirement in plumbing codes to ensure that wastewater drains don’t back up into your home. The air gap is the pipe that goes from your sink to the wall or floor. It’s required because it increases the distance between your drain pipe and any potential sources of contamination, like food particles or small animals.

Back siphonage occurs when the dishwasher drains into the sink, which could lead to disgusting sewage entering your home. The air gap helps prevent this by forcing water to flow down and not back up. If you don’t have an air gap in your kitchen, there are several other ways to ensure that your dishwasher drains correctly.

The most common alternatives to replacing an old dishwasher air gap are using a high loop, standpipe, or using a different model of valve. You can also replace the existing air gap and install an air gap fitting specifically designed for use with dishwashers instead.  

There are many ways to create an air gap — however, all of them need to be properly designed and installed to ensure their effectiveness.

If you’re looking for an alternative for your dishwasher, consider one of the following options:

Dishwasher Air Gap Alternatives

Using a High Loop

In many cases, installing a high loop drain pipe in place of the traditional dishwasher air gap can be an effective and affordable alternative.

A high loop is basically a pipe loop that rises above the highest point in the drain system, including any trap or P-trap extending from it. This protects against backflow by preventing any trapped sewer gas from flowing back into the house through this location.

The high loop is installed in the same way as a standard dishwasher air gap. The only difference is that it rises above the highest point of the drain system rather than being placed at that spot.

To connect the high loop straight to the drain, you’ll need to draw out as much extra length from the existing drain line as possible. Then, arch it up under the sink and against its underside.

The high loop should also be installed in an area that is easily accessible for cleaning and inspection. It’s important to keep this pipe free of debris, especially if there are other pipes extending from it. This will ensure that any trapped sewage doesn’t have a chance to flow back into the house through a hole or crack in the system.


Another option for preventing backflow contamination when you don’t have an air gap is using a standpipe. The standpipe is a vertical pipe that is used to allow water to flow out of a building. Standpipes are typically installed above the P-trap in the plumbing system and can be used to quickly drain the water in washing machines. They also provide an easy way to drain dishwashers.

However, it’s not the best option for preventing backflow contamination. It’s important to note that standpipes aren’t required by code and may not be suitable for every situation. They’re also more complicated to install than an air gap or high loop drainpipe, so it’s best to consult with a plumber before choosing this option.

A standpipe is more expensive than using a high loop since it requires several pieces of equipment in addition to installing a standpipe itself, but it’s still cheaper than installing multiple drain lines throughout your home just for your dishwasher.

Using a Check Valve

Check valves are generally installed inside a wall or floor. They work by allowing water to flow in one direction but not the other. For example, if you had a pipe running vertically through your wall, and it was connected to the outside of the building with a drainpipe that leaked into the basement (or vice versa), then this would be an ideal place for a check valve.

However, check valves are typically not up to code and are not allowed to be used as an alternative for regular air gaps in most areas. The check valve is not designed to handle tiny food particles that can go through dishwasher drainage systems at times.

If debris or food gets caught in a check valve, it could be unable to close properly and allow backflow. So, if you don’t want to be disgusted by the sight of sewage when opening your dishwasher, make sure that you use the appropriate air gap alternative.

Check valves are also much more difficult to install and maintain. If you do choose to use a check valve (not recommended), make sure you have a qualified technician install it for you.

How to install a dishwasher drain line alternative

Before installing a dishwasher drain line alternative, ensure that you comply with the plumbing code.

To connect the high loop straight to the drain, you’ll need to draw out as much extra length from the existing drain line as possible. Then, arch it up under the sink and against its underside.

Fasten a strap or pin to hold the loop in place and grab the end of your dishwasher’s drain line. To make the connection between a T-branch tailpiece and your drain hose, you will need to link together two pieces of tubing with a Y-branch and secure them in place using an appropriate clamp.

A dishwasher drain line is not too difficult to install; however, if you have never done this type of work before, it’s wise to call a professional plumber who can help you out with the installation.


When you’re building a new home or remodeling an existing one, it’s sometimes necessary to install an air gap in the dishwasher drain line. An air gap is a device that prevents the backflow of sewer gases into your dishwasher.

But if you don’t have enough room for an air gap — or if your local code requires one — there are alternatives.

Replacing an old dishwasher air gap is often a matter of installing either a high loop, standpipe, or different valve. You can also choose to replace the existing air gap and install a new fitting instead.

If you are unsure of which option is best for you, consult with a professional plumber.