Small nylon bottle brush
Use it for: Scrubs debris and slime out of the air gap body without gouging plastic.
Find a small cleaning brushDishwasher drain task
How to Clean a Dishwasher Air Gap
To clean a dishwasher air gap, remove the cap, lift out the inner cover, clear out food debris and sludge, then flush the air gap and drain hose path until water flows freely into the sink drain or garbage disposal again.
A clogged air gap usually shows up as water spurting or pooling around the small cylinder on the sink or countertop while the dishwasher drains. This is a straightforward cleanup job for most homeowners, as long as you stop if you find cracked parts, leaking hoses, or signs the blockage is deeper in the drain system.
Before you start: Most air gaps have a removable cap and inner cover, but sizes vary. Use a small nonmetal brush that fits inside the air gap without damaging plastic parts. Stop if the repair becomes unsafe or unclear.
Safety first
- Keep towels in place before testing so dirty drain water does not spread across the counter or floor.
- Use only light prying force on the cap to avoid cracking plastic or chipping the sink or countertop.
- Do not put your fingers deep into the air gap or disposal connection where you cannot see clearly.
- Stop if you find leaking hoses, broken plastic parts, or a blockage that requires plumbing disassembly beyond a simple cleaning.
Tools you may need
Flat screwdriver or butter knife
Use it for: Helps gently pry off the decorative cap if it is snug.
Shop flat screwdrivers
Needle nose pliers
Use it for: Useful for pulling out stubborn debris near the top of the air gap.
Find needle-nose pliers
Towels or paper towels
Use it for: Catch dirty water and protect the counter and sink area.
Shop absorbent shop towels
Cup or small bowl
Use it for: Lets you pour a little clean water through the air gap to flush it.
Find a small utility cup
Flashlight
Use it for: Helps you see inside the air gap and under the sink if you need to inspect the hose.
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Step-by-step fix
Step 1: Make sure the air gap is the likely problem
- Look for a small metal or plastic cylinder mounted near the sink faucet. That is the dishwasher air gap.
- Run a short drain cycle or cancel-drain on the dishwasher if it is safe to do so.
- Watch for water backing up, spurting, or leaking out around the air gap cap while the dishwasher tries to drain.
- Lay towels around the sink and air gap before you start cleaning.
If it works: You confirmed the air gap is present and likely clogged because water is coming out of it or draining poorly during the dishwasher drain cycle.
If it doesn’t: If your sink setup does not have an air gap, or no water comes out there, the problem may be in the dishwasher filter, drain hose, garbage disposal inlet, or sink drain instead.
Stop if:
- You see damaged wiring, a cracked countertop opening, or a loose air gap body that will not stay mounted.
- Water is leaking from under the sink rather than from the top of the air gap, which points to a hose or connection problem instead of a simple clog.
Step 2: Remove the cap and inner cover
- Twist or pull off the decorative outer cap by hand. If it sticks, gently lift it with a flat screwdriver or butter knife.
- Remove the inner plastic cap or cover underneath. Some lift straight off, and some twist slightly before lifting.
- Set both pieces in the sink so they do not fall behind the cabinet or into the disposal opening.
If it works: The top of the air gap is open and you can see inside the body.
If it doesn’t: If the cap will not come off with light pressure, wipe around the base and try again gently. Do not force it hard enough to crack the cap or countertop trim.
Stop if:
- The cap or inner cover breaks apart during removal.
- The air gap body itself turns loose in the sink or countertop and no longer feels secure.
Step 3: Clear out visible debris
- Use a flashlight to look down into the air gap opening.
- Pull out any food scraps, grease buildup, paper label pieces, or sludge with needle-nose pliers or your fingers if reachable.
- Scrub the inside walls and openings with the small nylon brush until the passage looks clear.
- Rinse the cap and inner cover under warm water and wipe away any buildup on those parts too.
If it works: The air gap opening and removable pieces are visibly cleaner, with loose debris removed.
If it doesn’t: If you cannot reach the blockage from the top, move on to flushing the air gap. That often loosens what the brush cannot grab.
Stop if:
- You find a hard obstruction that seems lodged deep in the plumbing path and will not move without disassembly.
- You notice cracked plastic inside the air gap that could leak after reassembly.
Step 4: Flush the air gap and nearby drain path
- Pour a small amount of clean water into the open air gap while watching where it goes.
- Let the water carry loosened debris into the sink drain or garbage disposal connection.
- Repeat the flush a few times until the water moves through without quickly backing up at the top.
- Wipe away any dirty water that spills onto the sink or counter.
If it works: Water poured into the air gap moves through more freely and does not immediately rise back to the top.
If it doesn’t: If water still backs up right away, check the dishwasher drain connection at the garbage disposal or sink drain for a deeper clog.
Stop if:
- Water leaks under the sink while you flush, which suggests a loose or damaged hose connection.
- The sink drain or garbage disposal is completely blocked and cannot accept any water.
Step 5: Check the hose path under the sink if needed
- Use a flashlight under the sink to find the larger hose running from the air gap to the garbage disposal or sink drain tailpiece.
- Look for a sharp kink, heavy grease buildup at the disposal inlet, or a loose clamp connection.
- Straighten any obvious kink carefully and wipe away buildup around the drain connection opening if you can reach it safely.
- If your garbage disposal was recently installed, make sure the dishwasher inlet was actually opened before use.
If it works: The hose path from the air gap to the drain looks open, connected, and free of obvious kinks or simple blockage points.
If it doesn’t: If the hose is clogged solid, split, or leaking at the connection, it may need to be removed or replaced rather than just cleaned from the top.
Stop if:
- The hose is cracked, brittle, or leaking.
- You need to disconnect plumbing that is seized, damaged, or likely to spill contaminated water into the cabinet.
Step 6: Reassemble and test a full drain
- Put the inner cover back on the air gap, then reinstall the outer cap.
- Run the dishwasher drain cycle again or start a short rinse cycle and let it reach the drain portion.
- Watch the air gap and listen for a smooth drain into the sink plumbing.
- Check under the sink one more time for drips while the dishwasher drains and for a minute after it stops.
If it works: The dishwasher drains without water spurting from the air gap, and there are no leaks at the top or under the sink.
If it doesn’t: If water still comes out of the air gap after cleaning, the clog is likely farther down the drain hose, disposal inlet, or sink drain and needs deeper clearing.
Stop if:
- The dishwasher still will not drain and you hear straining, grinding, or repeated pump noise.
- Any connection under the sink leaks during the test.
Verify the repair
- Run a drain or short rinse cycle and confirm no water spits out of the air gap.
- Make sure the dishwasher tub empties normally at the end of the cycle.
- Check under the sink for drips after the test.
- Use the dishwasher again on a normal load and confirm the fix holds in real use.
FAQ
What does a dishwasher air gap do?
It prevents dirty sink or drain water from siphoning back into the dishwasher. It also gives clogged drain water a place to spill out visibly instead of backing into the appliance.
Why is water coming out of the air gap?
Usually because the drain path after the air gap is restricted. Food debris, grease, or buildup in the air gap, hose, garbage disposal inlet, or sink drain can force water back up and out the top.
Can I clean a dishwasher air gap without taking apart plumbing?
Often yes. Many clogs are right at the top of the air gap and can be cleared by removing the cap, brushing out debris, and flushing it. If the blockage is deeper in the hose or drain connection, more work may be needed.
Do I need to turn off power or water first?
For basic air gap cleaning from the top, usually no. You are not opening electrical parts or water supply lines. If you plan to work near a garbage disposal connection or disconnect hoses, use extra caution and stop if the job goes beyond simple cleaning.
How often should I clean the air gap?
There is no fixed schedule for every home, but it is smart to clean it whenever you see slow draining, water spurting from the cap, or visible buildup around the opening.