Dishwasher Air Gap: What It Is, How to Clean It + Air Gap vs High Loop (2026)
Quick Fix: Water spurting from your air gap? Remove the chrome cap, pull out the plastic cover, and clear debris from the opening with a bottle brush. Then check the hose running from the air gap to the garbage disposal for clogs. If your dishwasher not draining problem continues after cleaning, the blockage is further downstream.
That chrome cylinder next to your kitchen faucet is a dishwasher air gap, and most homeowners never think about it until water starts spraying out of it mid-cycle. The good news: a clogged air gap is one of the easiest dishwasher drainage problems to fix yourself, usually in under 10 minutes.
Below we cover what air gaps do, how to clean one when it clogs, and whether you need an air gap or can get away with a high loop instead.
What Is a Dishwasher Air Gap?
A dishwasher air gap is a chrome-finished cylinder mounted on the sink or countertop that creates a physical break in the drain line, preventing sewage or contaminated water from backflowing into the dishwasher. It sits in the same hole where a soap dispenser or sprayer would go, typically right next to the faucet.
The device connects two hoses inside its body:
- Inlet hose (5/8” diameter) carries dirty water up from the dishwasher drain pump
- Outlet hose (7/8” diameter) carries that water down to the garbage disposal or drain tailpiece
Between the two connections is an open air chamber. Water flows up through the inlet, drops through open air, then falls into the outlet. That air break prevents contaminated water from siphoning backward into the dishwasher, even during a sewer backup.
Whirlpool’s air gap guide puts it simply: water cannot flow backward through an unpressurized gap.
GE specifies that when no air gap is installed, “the drain hose requires a high drain loop attached to the counter underside” as an alternative backflow prevention method. We cover that comparison next.
Air Gap vs High Loop: Which Do You Need?
The answer depends on where you live. Here is how the two methods compare:
| Feature | Air Gap | High Loop |
|---|---|---|
| Backflow protection | Complete physical air break | Partial, relies on gravity |
| Code compliance | Required in CA, WA, MN, HI | Accepted in most other states |
| Visibility | Visible on countertop | Hidden under sink |
| Cost | $5-$39 for unit + installation | Free (just reposition existing hose) |
| Maintenance | Needs periodic cleaning | Low maintenance |
| Failure mode | Water exits onto counter (visible warning) | Silent backflow possible |
An air gap is the only backflow prevention method that guarantees complete protection. A high loop relies on gravity and can fail if the drain hose sags over time, allowing contaminated water to siphon back into the dishwasher.
Air gaps are required by plumbing code in California, Washington, Minnesota, and Hawaii. Most other states allow a high loop as an acceptable alternative. This state-by-state air gap reference covers the specifics, or call your city building department.
Use an air gap when:
- Your state or county code requires it
- Your drain hose connects below 20 inches from the floor
- You want guaranteed backflow protection
- You have a septic system (higher backflow risk during backups)
A high loop works when:
- Your local code allows it
- You prefer a cleaner countertop look
- Your dishwasher drain hose high loop connects to a garbage disposal with the knockout plug properly removed
Code tip: Not sure what your local code requires? Check with your city or county building department before removing an existing air gap.
Video Guide
Video: “Dish Washer Not Draining Air Gap Water Coming Out” by Fort Knox Co.
How to Clean a Clogged Dishwasher Air Gap
Cleaning a clogged dishwasher air gap takes about 5-10 minutes. Do this before calling a plumber. The fix is almost always simple debris removal.
Tools you need:
- Bottle brush or pipe cleaner
- Small flashlight
- Pliers (for stubborn caps)
- Towel (water will spill)
Step 1: Remove the Chrome Cap
Lift or twist off the decorative chrome cap on top of the air gap. Most caps pull straight up. If yours is stuck, wrap pliers in a cloth and gently twist counterclockwise.
Step 2: Remove the Plastic Inner Cover
Under the chrome cap sits a plastic diverter cover. Pull it straight up or unscrew it depending on the model. This exposes the inside of the air gap body.
Step 3: Inspect and Clear the Opening
Shine a flashlight into the opening and look for food particles, grease, or mineral buildup. Remove visible debris with your fingers or tweezers, then scrub the interior walls with a bottle brush.
Step 4: Check the Outlet Hose
The 7/8” outlet hose runs from the bottom of the air gap down to the garbage disposal inlet. Most clogs happen here. Disconnect the hose from the disposal, look through it for blockages, and use a long bottle brush or skinny drain snake to clear debris. Check that the hose is not kinked under the sink.
Step 5: Flush the Drain Path
Pour hot water directly into the air gap opening from above. Watch whether it flows freely out the outlet hose. If water backs up, the outlet hose still has a blockage and needs another pass with the brush or snake.
For stubborn mineral buildup, pour 1 cup of vinegar through the air gap opening. Follow with 1 cup of baking soda, let the mixture sit for 15-20 minutes, then flush with hot water.
Step 6: Clear the Shared Drain Path
Before testing, run your garbage disposal for 30 seconds to clear any food waste from the shared drain. GE recommends always running the disposal before the dishwasher to keep the drain path clear.
Step 7: Reassemble and Test
Replace the plastic diverter cover first, then snap the chrome cap back on. Run a full dishwasher cycle and watch the air gap for any water leaking out. If water flows normally, the clog is fixed.
Never use chemical drain cleaners in or near the air gap. GE explicitly warns against using drain cleaner in the dishwasher system, and the chemicals can damage plastic hoses and rubber seals.
Step 8: Still Not Draining?
If cleaning the air gap does not solve the problem, the clog may be deeper in the drainage system. Clean your dishwasher filter next, since filter blockages are the other common cause of standing water. A foul smell from the air gap opening often means trapped food debris is decomposing in the hose, which could also cause dishwasher drain smells.
Cleaned the air gap but still not draining? The problem may be a kinked drain hose or a failed drain pump not working.
How to Install a Dishwasher Air Gap
Installing an air gap is a 20-30 minute job. No plumber needed. An air gap kit costs $5-$39 at any hardware store. GE’s drainage troubleshooting guide covers when an air gap is required versus when a high loop is acceptable.
Tools and materials:
- Drill with 1-3/8” hole saw (if no existing hole)
- Adjustable pliers
- 2 hose clamps
- Dishwasher air gap kit
Steps:
- Drill or locate the mounting hole. Standard air gap hole size is 1-3/8”. Many sinks have a pre-punched knockout for this purpose.
- Insert the air gap body through the hole from above.
- Secure with the mounting nut from below the countertop.
- Connect the 5/8” inlet hose from the dishwasher drain outlet to the air gap inlet.
- Connect the 7/8” outlet hose from the air gap outlet to the garbage disposal inlet or drain tailpiece.
- Secure both hoses with clamps. Loose connections are the most common cause of leaks after installation.
- Attach the decorative cap on top.
- Run a test cycle and check every connection point for leaks.
Key measurements: The standard dishwasher air gap uses a 5/8-inch inlet hose and a 7/8-inch outlet hose, mounted through a 1-3/8-inch countertop hole.
Important: If you are connecting to a new garbage disposal, confirm that the dishwasher knockout plug inside the disposal inlet has been removed. GE lists this as a common cause of drainage failure on new installations.
When to Replace Your Air Gap
Cleaning fixes most air gap problems, but sometimes the unit itself needs replacing. Replacement units cost $5-$39. Doing it yourself saves $50-$100 in labor (professional rate: $50-$100 per hour, Fixr 2026).
Replace your air gap when:
- The plastic body is cracked or broken
- Leaking continues after thorough cleaning (seal failure)
- Metal parts show heavy corrosion
- The cap is discolored and no longer matches your kitchen finish
If replacing the air gap does not fix your drainage problem, the issue is likely deeper in the system. Test your drain pump not working or check whether your check valve replacement is due. A professional diagnostic costs $50-$75 for the service call (Fixr, 2026).
FAQ
Do you really need an air gap for a dishwasher?
It depends on local code. California, Washington, Minnesota, and Hawaii require air gaps by state plumbing code. Most other states allow a high loop as an alternative. Even where not required, an air gap provides the strongest backflow protection. Check with your local building department before deciding.
How do I know if my dishwasher air gap is clogged?
Water will spurt or overflow from the air gap cap while the dishwasher drains. You may also notice the dishwasher not draining completely, water pooling on the countertop near the air gap, or gurgling sounds during the drain cycle.
Which states require a dishwasher air gap?
California, Washington, Minnesota, and Hawaii mandate air gaps by state plumbing code. Many other states leave the requirement to local jurisdiction, so your county or city may still require one even if the state does not.
What is the alternative to a dishwasher air gap?
A high loop is the most common alternative. The drain hose is looped as high as possible under the countertop (ideally touching the underside at 32-36 inches from the floor) and secured with a bracket or zip tie. A high loop uses gravity to prevent backflow but does not provide the same guaranteed protection as a physical air gap.
Can I pour vinegar down the dishwasher air gap?
Yes. Pour 1 cup of vinegar through the air gap opening to dissolve mineral buildup. For tougher clogs, follow with 1 cup of baking soda, let the mixture sit 15-20 minutes, then flush with hot water. We use this method regularly and find it clears most minor buildup without tools.
Still having trouble? Start with our complete dishwasher not draining guide for step-by-step diagnosis covering every possible cause.