How to Clean a Dishwasher That's Not Draining
Standing water in the bottom of your dishwasher is usually caused by a clogged filter, blocked drain hose, or dirty air gap. Fix it in 30 minutes with no special tools — and no service call.
Repair & Refinish Team
Published March 14, 2026 · Updated March 21, 2026
What You'll Need
- Towels or sponge
- Screwdriver (Phillips or Torx, depending on model)
- Shallow pan or baking dish
- Wire hanger or pipe cleaner
- Flashlight
- White vinegar (2 cups)
- Baking soda (1/2 cup)
- Dish soap
- Replacement air gap cap (if cracked)
Cost Estimate
Budget
$0
Mid-Range
$5
Premium
$15
An appliance repair service call costs $100-$200 for this diagnosis. DIY cost is $0-$15 (you likely already have what you need).
Step-by-Step Instructions
Run the Garbage Disposal
Step 1 of 6If your dishwasher drains through the garbage disposal, the disposal itself may be clogged. Turn on the disposal and run hot water for 30 seconds. If the disposal is clear, the clog is elsewhere. If the disposal grinds but doesn't drain, the disposal drain is clogged (clear it with a plunger on the sink). This single step fixes the problem about 20% of the time.
If you recently installed a new garbage disposal, check that the knockout plug has been removed from the dishwasher inlet. This is the #1 overlooked cause of dishwasher drainage failure after a new disposal install.
Clean the Dishwasher Filter
Step 2 of 6Remove the bottom dish rack. Locate the filter assembly at the bottom of the dishwasher near the spray arm (it's a cylindrical screen or a flat filter cover). Twist the filter counterclockwise and pull it out. You'll likely find a gross buildup of food particles, grease, and debris. Rinse the filter under hot running water and scrub with an old toothbrush and dish soap. For stubborn grease, soak the filter in hot vinegar water for 10 minutes.
Clean the filter once a month to prevent drainage problems. Most dishwashers built after 2010 have a manual filter that needs regular cleaning (older models had self-cleaning grinders).
Clear the Drain Basket and Sump
Step 3 of 6With the filter removed, look into the sump area (the recessed space where the filter was). Remove any food debris, broken glass, or foreign objects you see. Use a flashlight to check for blockages. You may find a bottle cap, piece of bone, or chunk of label that's blocking the drain port. Check the drain port opening and clear it with a straightened wire hanger if it appears clogged.
Check and Clean the Air Gap
Step 4 of 6If your sink has an air gap (a small chrome cylinder usually next to the faucet), remove the decorative cap and the inner cap. Look inside for food debris. Clean it out with a bottle brush or pipe cleaner. Water and food particles sometimes back up through the air gap, indicating a clog between the air gap and the disposal. Blow compressed air through the hose from the air gap to the disposal to clear it.
Inspect the Drain Hose
Step 5 of 6The drain hose runs from the dishwasher pump to the garbage disposal or sink drain. Check under the sink where the hose connects — disconnect it and inspect for kinks, clogs, or buildup. A kinked hose is a common cause of poor drainage, especially if the dishwasher was recently installed or the cabinet was reorganized. Blow through the hose to check for blockages (or use a flashlight to see through it). Straighten any kinks and reconnect.
Place a towel or shallow pan under the drain hose connection before disconnecting it. Water in the hose will spill when you remove it.
Run a Cleaning Cycle and Test
Step 6 of 6Reinstall the filter and replace any parts you removed. Place a cup of white vinegar in a dishwasher-safe measuring cup on the top rack and run a hot water cycle (empty dishwasher). This flushes the drain system and removes grease buildup. When the cycle ends, open the dishwasher and check for standing water — there should be little to no water in the bottom (a thin film is normal).
After the vinegar cycle, sprinkle 1/2 cup of baking soda on the bottom of the tub and run another short hot cycle. This freshens the interior and removes odors.
Recommended Products
Drop-in cleaning tablets that dissolve mineral buildup, grease, and food residue inside the dishwasher tub, pump, and drain. Use monthly for optimal performance.
Liquid cleaner that targets grease and limescale in the hidden parts of your dishwasher. Place upside-down in the bottom rack and run empty. Works in a single cycle.
Replacement air gap assembly with cap, body, and hose. Chrome finish matches most kitchen fixtures. Easy 10-minute installation. Prevents dishwasher backflow.
Affiliate Disclosure: We earn a small commission when you buy through our links at no extra cost to you.
Tips & Warnings
- Clean the dishwasher filter once a month. This single habit prevents 90% of drainage problems.
- Scrape plates before loading (no need to pre-rinse, but remove large food pieces). Seeds, bones, and labels are common culprits.
- Run hot water at the kitchen faucet for 30 seconds before starting the dishwasher. This ensures the first fill is hot, which dissolves grease better.
- Run the garbage disposal before starting the dishwasher. A clogged disposal blocks the dishwasher drain path.
- Never put your hand into the dishwasher sump without first checking for broken glass. Use a flashlight and pliers to remove sharp objects.
- If the dishwasher is completely full of standing water (not just a puddle), bail most of it out before removing the filter to avoid a flood.
- If you smell gas near the dishwasher, leave the house and call your gas company. Some dishwashers are near gas lines that could have shifted.
Frequently Asked Questions
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