Key Takeaways
- Standing water usually means a clog, a blocked drain hose, a faulty pump, or an electrical/control fault.
- Start with simple checks: filter, sink/disposal connection, and drain hose before moving to the pump.
- Many blockages are DIY-fixable; electrical or pump faults usually require a service technician.
- Always cut power and be careful with sharp parts; contact a pro if you’re unsure or see electrical damage.
Common Symptoms
- Standing water at the bottom of the dishwasher after a cycle
- Dishwasher completes cycle but water remains
- Gurgling or bubbling sounds during draining
- Unpleasant odors coming from standing water
- Error codes or flashing lights indicating drain fault
Possible Causes & Solutions
Clogged or dirty dishwasher filter and sump
How to Identify: Remove the bottom rack and inspect the filter and sump area for food debris, grease, and sediment. If water drains slowly after removing large particles, the filter or sump is likely the issue.
Solution: Remove and clean the filter (usually twist-and-lift) with warm soapy water and a soft brush. Clear debris from the sump and screen. Reassemble and run a short rinse cycle to test. Regular cleaning prevents recurrence.
DIY: Yes
Blocked or kinked drain hose
How to Identify: Locate the drain hose under the sink or behind the dishwasher. Check for visible kinks, loops that trap water, or blockages by disconnecting the hose (place a bucket underneath). Run water through the hose or use a plumber’s snake if accessible.
Solution: Straighten kinks and flush the hose with water. If clogged, detach and use a flexible brush or small auger to clear it. Replace the hose if cracked, collapsed, or permanently clogged. Ensure proper high loop or air gap is present when reinstalling.
DIY: Yes
Garbage disposal knockout plug or disposal blockage
How to Identify: If the dishwasher drain ties into the garbage disposal, check whether the knockout plug was removed when the disposal was installed. Run the disposal with the dishwasher disconnected and check for blockages or poor drain performance.
Solution: If the disposal is new and the knockout plug wasn’t removed, remove it following manufacturer instructions (power off first). Clear disposal clogs and run water to ensure free flow. Reconnect the dishwasher and test.
DIY: Yes
Faulty drain pump or motor
How to Identify: Listen for the pump running during the drain cycle. If the pump is silent or makes grinding or humming noises without moving water, it may be faulty. You can access the pump when power is off and try to rotate the impeller gently to check for obstructions.
Solution: First, clear any debris around the impeller. If the pump hums or doesn't run, it often requires replacement. Replacing a pump involves electrical wiring and may require removing the dishwasher—consider a professional if unfamiliar with appliance repairs.
DIY: No - Professional recommended
Clogged air gap or improper air gap installation
How to Identify: If your sink has an air gap (small cylinder above the sink), remove the cap and inspect for debris. Water or food can block the air gap, preventing proper draining. Also check that the air gap hoses aren’t kinked.
Solution: Clean the air gap by removing the cap and flushing with water; use a brush to remove buildup. Ensure hoses are installed correctly with a high loop and no kinks. Replace damaged components if necessary.
DIY: Yes
Control board or timer/electrical failure
How to Identify: If all mechanical parts are clear and the pump doesn't activate or the dishwasher shows electronic/drain error codes, the control board, timer, or wiring may be faulty. Inspect wiring for burn marks or loose connections only after power is off.
Solution: Electrical diagnosis and replacement of control boards or timers are advanced tasks. Unless you have appliance electrical experience, contact a qualified technician for safe testing and replacement.
DIY: No - Professional recommended
When to Call a Professional
Call a professional when you encounter electrical damage, persistent leaks, or when the drain pump or internal motor needs replacement. Technicians have the tools to safely test voltage, remove and replace pumps, and reseal plumbing connections. If odor or backed-up water is spreading to other drains or causing contamination, a pro can diagnose connected plumbing issues. Also hire a professional if you’re uncomfortable working with wiring, removing the dishwasher from cabinetry, or if clearing visible clogging doesn’t restore drain function. A certified appliance repair technician will provide a safe, efficient repair and can advise on replacement cost vs. repair when the unit is older.
Frequently Asked Questions
How do I clean my dishwasher filter?
Locate the filter at the bottom of the dishwasher under the lower spray arm—typically a twist-and-lift or pull-out design. Remove food particles by hand, then wash the filter with warm soapy water and a soft brush. Reinstall and run a rinse cycle. Regular monthly cleaning prevents most filter-related drain issues.
Can a clogged garbage disposal stop my dishwasher from draining?
Yes. Many dishwashers drain into a garbage disposal. If the disposal is clogged or the knockout plug wasn’t removed when the disposal was installed, water can back up into the dishwasher. Clear the disposal by cutting power, using a disposal wrench, and running it with water before retesting the dishwasher.
Is it safe to run the dishwasher if it’s not draining?
No. Running a cycle with standing water can worsen clogs, cause leaks, or damage the pump. Turn off power to the dishwasher and address the cause. If you must rinse dishes, do so by hand until the issue is fixed.
How much does it cost to replace a dishwasher drain pump?
Costs vary by model and labor rates. Parts typically range from $50–$200; labor can add $100–$300. Older or less common models may cost more. Get a diagnosis and written estimate from a qualified technician before authorizing repairs.