Where is an Air Gap commonly found?

An Air Gap commonly appears at dishwasher drain connections, water treatment equipment, and other points where a clean supply could meet wastewater.

Can an Air Gap become blocked?

Yes, an Air Gap can become blocked by debris, mineral buildup, or a misplaced cover. A blockage can interfere with drainage and reduce backflow protection.

Does an Air Gap need moving parts?

No, an Air Gap needs no spring, valve, or rubber seal. The open separation provides protection by breaking the physical path for reverse flow.

Glossary

What Is an Air Gap?

An Air Gap is a physical separation between a water outlet and the receiving vessel or drain. The open space prevents contaminated water from flowing backward into the clean water supply. Plumbing systems use air gaps in places where backflow could create a health risk or affect the quality of drinking water.

Quick Facts About Air Gap

Key Takeaways About Air Gap

An open space separates the outlet from the receiving surface.
The gap blocks backflow without relying on a spring or seal.
An Air Gap is not the same as a vacuum breaker.

How Air Gap Works

Two men inspect a leaking kitchen sink with blueprints and tools on the counter

An Air Gap works by leaving open space between a water outlet and the place receiving the water. If the downstream water becomes pressurized or contaminated, the open space breaks the path back to the supply.

Related glossary terms: Vacuum Breaker, Backwater Valve, Trap Primer.

Backflow testing can include checking whether the air gap stays clear and visible. The outlet must discharge freely into the receiving fixture or drain. Objects, buildup, or a changed fitting can close that separation and remove the protection.

A dishwasher drain connection offers a common example. The drain hose may rise beneath the countertop or connect through an air gap fitting, so dirty sink water cannot flow back into the dishwasher.

A chrome kitchen faucet cap sits in a sink hole, with water dripping down the stainless steel basin

Expert Note

When we check an Air Gap during Backflow Testing, we inspect the open separation and the outlet path. We also look for debris, altered fittings, or drainage conditions that could reduce the gap’s protection. Our team records the condition clearly so the plumbing system can be evaluated by its actual setup.

Air Gap in Practice: A Real-World Example

A dishwasher drains through an air gap fitting mounted near the sink. During Backflow Testing, the technician checks that the fitting remains open and that discharge can reach the sink or drain without blockage.