Dishwasher Not Draining? 5 Common Causes
You start your dishwasher, let it run through a full cycle, and open the door expecting clean dishes. Instead, there is dirty standing water in the bottom of the tub.
Before you assume your dishwasher needs to be replaced, start with the most common causes. A dishwasher that will not drain often has a clog, installation issue, or failed part that may be much less expensive than a new appliance.
Why Is My Dishwasher Not Draining?
The most common reasons a dishwasher will not drain are:
- A clogged dishwasher filter
- A blocked drain hose
- A clogged garbage disposal connection or air gap
- A faulty drain pump
- A stuck check valve or drain solenoid
Dishwasher Not Draining Troubleshooting Guide
| Symptom | Possible Cause | What To Check First |
|---|---|---|
| Standing water in the bottom | Clogged filter | Remove and clean the filter assembly |
| Dishwasher drains slowly | Blocked drain hose | Inspect the hose for clogs or kinks |
| New dishwasher will not drain | Garbage disposal knockout plug | Make sure the knockout plug was removed |
| Humming sound but no draining | Faulty drain pump | Check the pump for debris or failure |
| Water drains then comes back | Bad check valve | Inspect the valve for sticking or damage |
The Most Common Fix
For many homeowners, the first thing to check is the dishwasher filter. Food particles, grease, broken glass, paper labels, and small debris can collect in the bottom of the dishwasher and block water from draining properly.
Before replacing parts, remove the lower rack, take out the filter assembly, rinse it under warm water, and clear any debris around the sump area.
Parts That May Fix a Dishwasher That Won't Drain
- Dishwasher Drain Pump
- Drain Hose
- Filter Assembly
- Check Valve
- Drain Solenoid
- Sump Assembly
Always verify compatibility using your model number before ordering replacement parts.
1. A Clogged Dishwasher Filter
A clogged filter is one of the most common reasons a dishwasher leaves water in the bottom after a cycle. The filter is designed to catch food particles and debris before they reach the drain system.
Signs of a clogged dishwasher filter include:
- Standing water after the cycle ends
- Dirty water in the bottom of the tub
- Bad odors coming from the dishwasher
- Food particles left on dishes
- Slow draining
Remove the lower rack and clean the filter assembly. If the filter is damaged, cracked, or missing pieces, it may need to be replaced.
2. A Blocked Drain Hose
The drain hose carries dirty water from the dishwasher to the sink drain, garbage disposal, or plumbing connection. If the hose is kinked, crushed, or clogged with grease and food debris, the dishwasher may not drain correctly.
Signs of a blocked drain hose include:
- Water drains slowly
- Standing water remains after the cycle
- Gurgling sounds near the sink
- Water backs up into the dishwasher
Check the drain hose behind or under the dishwasher. Make sure it is not kinked or crushed. If the hose is clogged or damaged, it may need to be cleaned or replaced.
3. A Clogged Garbage Disposal Connection or Air Gap
If your dishwasher drains through a garbage disposal, the connection can become blocked. On newer installations, the disposal knockout plug may not have been removed.
Signs of a disposal or air gap issue include:
- The dishwasher has not drained correctly since installation
- Water backs up into the sink
- Water leaks or sprays from the air gap
- No clog is found in the dishwasher filter
If the dishwasher was recently installed, confirm that the garbage disposal knockout plug was removed. If your sink has an air gap, remove the cap and clean out any debris inside.
4. A Faulty Drain Pump
The drain pump pushes water out of the dishwasher during the drain cycle. If the pump is clogged, jammed, or failing electrically, the dishwasher may leave water in the tub.
Signs of a possible drain pump problem include:
- The dishwasher hums but does not drain
- The drain cycle sounds different than normal
- Water remains after the filter and hose are clear
- The dishwasher stops mid-cycle with water inside
Sometimes debris such as glass, plastic, or food particles can jam the pump. If the pump is clear but still does not operate, it may need to be replaced.
5. A Stuck Check Valve or Drain Solenoid
Some dishwashers use a check valve or drain solenoid to control water flow. The check valve helps prevent drained water from flowing back into the dishwasher.
Signs of a valve or solenoid issue include:
- Water drains but returns to the tub
- Draining works sometimes but not every cycle
- The dishwasher leaves a small amount of dirty water
- Other drain parts appear clear
If the check valve is stuck open, dirty water can flow back into the dishwasher. If the drain solenoid fails, the dishwasher may not activate the drain system correctly.
Before You Buy a New Dishwasher
Many homeowners assume standing water means the dishwasher is finished. In reality, the issue may be a clogged filter, blocked hose, garbage disposal connection, drain pump, or another replaceable part.
Save the appliance. Save your money.
Before replacing the entire dishwasher, check the simple causes first.
When To Call A Professional
If you have cleaned the filter, checked the drain hose, inspected the garbage disposal connection, and the dishwasher still will not drain, it may be time for a professional diagnosis.
A failed drain pump, electrical problem, control issue, or internal blockage may require testing beyond basic homeowner maintenance.
Frequently Asked Questions
Why is there standing water in my dishwasher?
Standing water is usually caused by a clogged filter, blocked drain hose, clogged garbage disposal connection, faulty drain pump, or bad check valve.
What should I check first if my dishwasher is not draining?
Start with the dishwasher filter. Remove the lower rack, clean the filter assembly, and check for debris around the drain area.
Can a garbage disposal stop a dishwasher from draining?
Yes. If the dishwasher drains through the garbage disposal, a clog or an unremoved knockout plug can prevent water from draining properly.
Can I run my dishwasher if it is not draining?
It is not recommended. Running the dishwasher with standing water can cause odors, poor cleaning, leaks, and possible damage to internal parts.
How often should I clean my dishwasher filter?
Most homeowners should clean the dishwasher filter about once per month.
Is it worth repairing a dishwasher that will not drain?
Often, yes. Many dishwasher draining problems are caused by clogs, installation issues, or replaceable parts that cost much less than a new dishwasher.
Final Thoughts
A dishwasher that will not drain can be frustrating, but it does not always mean the appliance needs to be replaced. Start with the simple causes first: clean the filter, check the drain hose, inspect the garbage disposal connection, and clear any visible debris.
If the problem continues, a common replacement part may be the fix.
Before you replace it, check the part.
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