When Should You Choose a Double Dishwasher Air Gap?

On this page (6 sections)

1. When does a double dishwasher air gap make sense?
2. How do you check whether a dual-inlet fitting will fit?
3. What should you check before connecting two drains?
4. Can one air gap serve two dishwashers at the same time?
5. Does a double air gap belong on the counter?
6. What should you choose for two dishwasher drains?

Choose a double dishwasher air gap when two dishwasher drain hoses need to connect through one dual-inlet fitting. It can suit a kitchen with two dishwashers, but only if the fitting matches both hoses and the installation follows local plumbing rules.

A standard air gap may have only one dishwasher inlet. A dual-inlet fitting is a specific solution for two drain lines, not a reason to join hoses with an improvised adapter.

If you’re new to air gaps, start with What Is an Air Gap on a Countertop Dishwasher?. This guide focuses on when a dual-inlet fitting makes sense and what to confirm before installation.

When does a double dishwasher air gap make sense?

Choose a double air gap when two separate dishwasher drain hoses must connect to one air-gap assembly. This can apply in a kitchen with two dishwashers, such as one main unit and a second appliance used for a different load.

The fitting must be made for two inlets. Don’t assume a single-inlet air gap can take both hoses, and don’t connect the drains with a homemade splitter.

Before buying, check:

• That the fitting has two dishwasher inlets.
• The inlet size needed for each hose.
• How the fitting connects to the sink drain or disposal.
• Whether the appliance instructions allow the planned drain route.
• Whether local plumbing rules allow this arrangement.

A dual-inlet fitting may not be needed if each dishwasher already has a separate approved drain connection. Compare the full drain layout before deciding.

How do you check whether a dual-inlet fitting will fit?

Check both hose diameters and every connection point against the fitting’s instructions. A fitting that accepts one hose does not automatically accept the second.

Measure each hose at the end that will connect to the air gap. Then compare those measurements with the fitting’s inlet sizes and confirm what outlet connection it requires.

The Design House 522953 kit has 5/8 in and 7/8 in inlets, but its product information describes a single dishwasher air gap. It does not identify the kit as a dual-inlet fitting, so don’t treat it as a two-dishwasher solution.

If the hose sizes differ, confirm that the fitting supports both sizes in the specific configuration you need. Avoid forcing a hose onto an inlet or relying on an adapter that the fitting maker does not approve.

What should you check before connecting two drains?

Confirm the drain route, connection method, and local requirements before installation. The air gap has to be part of a suitable plumbing arrangement; choosing a dual-inlet cap alone does not mean the rest of the setup is right.

Check the instructions for both dishwashers and the air gap. Look for the allowed hose routing, connection points and any limits on sharing a drain assembly.

If you’re matching the visible cap to your faucet, the best dishwasher air gap kit guide can help compare kit options. For a black finish, see best dishwasher air gap matte black.

The KRAUS air gap is described as compatible with all dishwashers, but that does not say it has two dishwasher inlets. Check the actual fitting configuration before selecting it for a shared setup.

If two hoses must meet at one fitting and the instructions don’t make the arrangement clear, ask a licensed plumber. A professional can check the connections against the local code and appliance requirements.

Can one air gap serve two dishwashers at the same time?

It can only if the dual-inlet fitting is designed for that use and the full drain setup is approved. The word “double” does not by itself confirm that both appliances can drain through the fitting at once.

Look for instructions that address two dishwasher connections, including whether both inlets can be used together. If the instructions cover only one dishwasher or leave simultaneous use unclear, get guidance from the maker or a plumber before connecting both.

Don’t join the hoses with a tee or reducer simply because the parts fit. A physical connection does not prove the drain will work correctly or meet local requirements.

Does a double air gap belong on the counter?

A sink-deck or countertop air gap should be installed in the position its instructions specify. Moving a conventional air gap under the sink can change how it works, so don’t conceal it below the counter without confirming the fitting is designed for that location and local rules permit it.

For a standard air gap, check the counter or sink deck for a suitable mounting hole and confirm there is enough room beneath it for the body and hoses. If you’re considering a hidden setup, read can a dishwasher air gap go under a sink.

The PetrelWing kit is described as a single air-gap kit with a plastic body and brass cap. Its product information does not confirm a dual-inlet design, so verify the fitting itself before considering it for two dishwasher drains.

What should you choose for two dishwasher drains?

Choose a purpose-built dual-inlet fitting if both dishwasher drain hoses need to connect through one air gap. Verify that its instructions support your hose sizes, drain connection and intended use.

If your two appliances have separate approved drain paths, use the arrangement specified for those appliances instead of adding a shared fitting. If the plan depends on an adapter, a concealed air gap or simultaneous drainage that the instructions don’t address, ask a plumber to review it before installation.

For a double dishwasher air gap, pick a fitting whose instructions explicitly support two drains; pick a standard single-inlet air gap only when one dishwasher hose needs a connection. Check the hose sizes and local requirements before buying.

Frequently asked questions

What is a double dishwasher air gap?

A double dishwasher air gap is a dual-inlet fitting intended to connect two dishwasher drain hoses. It still needs a suitable drain connection and correct hose routing.

Check the fitting's instructions and local plumbing rules before using one, since a standard air gap may have only one dishwasher inlet.

Can two dishwashers share one air gap?

Two dishwashers may share a dual-inlet air gap if the fitting is designed for both drains and the installation complies with local rules. Confirm that both hose sizes fit, the drain connection is suitable, and the instructions permit simultaneous use.

Ask a plumber if the layout is unclear.

Does every double air gap fit two dishwashers?

No. Check the number and size of the inlets, the outlet connection, and the maker's installation instructions.

The word “double” alone does not confirm hose compatibility or that the fitting can handle your specific drain arrangement.

Do I need a double air gap for two dishwashers?

You need a dual-inlet fitting only when both dishwasher drains must connect through one air gap. If each dishwasher has its own approved drain arrangement, a shared fitting may not be needed.

Check local plumbing rules and appliance instructions before choosing.

Can I put a dishwasher air gap under the sink?

A conventional countertop air gap is designed to sit above the sink deck or counter, so placing it under the sink may not preserve its intended function. Check local requirements and the fitting instructions; see our guide to whether a dishwasher air gap can go under a sink.