Few things are more frustrating than opening your dishwasher and finding dirty water sitting in the bottom. The good news is that many drainage problems can be fixed without replacing expensive parts.
Before scheduling a service call, check these common causes.
- Check the Dishwasher Filter
Most modern dishwashers have a removable filter at the bottom of the tub.
Food particles, grease, and debris can clog the filter and restrict water flow.
What to Do:
- Remove the lower rack.
- Twist and remove the filter.
- Wash it thoroughly under warm water.
- Reinstall and test the dishwasher.
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- Inspect the Drain Hose
The drain hose carries wastewater from the dishwasher to the sink drain or garbage disposal.
Common problems include:
- Kinks
- Clogs
- Crushed sections
Disconnect and inspect the hose if accessible.
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- Check the Garbage Disposal
If a garbage disposal was recently installed, the knockout plug may still be in place.
This completely blocks dishwasher drainage.
Signs:
- Dishwasher won’t drain after installation.
- Water backs up into the sink.
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- Clean the Air Gap
Some homes have an air gap mounted near the kitchen faucet.
Food debris can clog the air gap and prevent proper drainage.
Remove the cap and clean out any buildup.
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- Inspect the Drain Pump
The drain pump pushes water out of the dishwasher.
Common symptoms of a failing pump include:
- Humming noise
- Standing water
- Intermittent draining
Check for broken glass, food, or debris that may be jamming the impeller.
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- Verify the Drain Solenoid
Some dishwashers use a drain solenoid to redirect water during the drain cycle.
A failed solenoid may prevent the unit from draining properly.
Signs include:
- No drain activity
- Buzzing sounds
- Water remaining after every cycle
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- Check the Control Board
If all mechanical components test good, the electronic control board may not be sending power to the drain system.
This is less common but can occur after power surges or electrical failures.
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Most Common Causes Ranked
In order of likelihood:
- Clogged filter
- Blocked drain hose
- Garbage disposal knockout plug
- Dirty air gap
- Drain pump obstruction
- Failed drain pump
- Control board issue
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Estimated Repair Costs
Repair Estimated Cost
Filter Cleaning Free
Drain Hose $15-$40
Air Gap Cleaning Free
Drain Pump $50-$200
Control Board $150-$400
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Final Thoughts
A dishwasher that won’t drain doesn’t automatically mean an expensive repair. Most problems are caused by clogs, filters, hoses, or simple drainage restrictions that homeowners can often fix themselves.
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