Dishwasher Not Draining? Causes and Fixes

First, rule out the easy stuff

Before taking anything apart, make sure the cycle actually finished. Opening the door mid-cycle, a power blip or someone leaning on the buttons can stop a cycle before the drain step. Close the door and run a short rinse or a drain/cancel cycle. If the water goes, there’s nothing wrong with the machine.

Step-by-step checks you can do

1. Turn off the power at the breaker. Safety first, since you’ll have your hands in water.
2. Bail out the standing water with a cup and towels.
3. Clean the filter. Twist it out of the bottom of the tub and scrub it under hot water. Look for labels, glass, popcorn kernels, seeds and plastic film in the sump underneath.
4. Run the garbage disposal with water for 20 seconds. Many Naperville kitchens route the dishwasher drain through the disposal, and a backed-up disposal stops the dishwasher from draining.
5. New disposal? If one was just installed, check that the knockout plug inside the dishwasher inlet was removed. If it wasn’t, the dishwasher has nowhere to drain. This is one of the most common causes after a new install.
6. Check the sink. If the sink drains slowly too, the clog is in the house plumbing, not the dishwasher.
7. Look under the sink at the drain hose. It should rise in a high loop (or run to an air gap on the sink deck) and shouldn’t be kinked or crushed behind storage bins.
8. If you have an air gap (the small chrome cap beside the faucet), pull the cap off and clear any debris.
9. Restore power and run a short cycle. Listen at the end: a hum with no water moving points to the drain pump.

Causes a tech looks for

Cause	How to tell	Typical fix
Clogged filter or sump	Dirty water, food smell, slow draining	Clean the filter and sump
Backed-up disposal or sink drain	Sink drains slowly too	Clear the disposal or call a plumber
Knockout plug left in	Started right after a new disposal install	Remove the plug from the disposal inlet
Kinked or clogged drain hose	Hose crushed under the sink, or packed with debris	Straighten, flush or replace the hose
Clogged air gap	Water spits out of the cap by the faucet	Clean the air gap
Drain pump jammed	Humming at drain time, glass or a seed under the pump cover	Clear the impeller
Drain pump failed	No hum, no draining, filter and hose clear	Replace the drain pump
Check valve stuck	Dirty water flows back into the tub	Clean or replace the check valve
Control or wiring	Pump tests fine but never gets power	Diagnose the board or harness

The Naperville angle

The median home in Naperville was built in 1990. In many of those kitchens the dishwasher still drains through an aging disposal and a drain hose that’s been pushed around by years of under-sink storage. A slow disposal or a crushed drain hose can look exactly like a failed pump, so a good tech checks both before quoting you a pump.

Error codes that mean a drain problem

Brand	Code	Meaning
Bosch / Thermador	E24	Drain blocked: hose, filter or disposal connection
Bosch / Thermador	E25	Drain pump cover or impeller obstructed
Bosch / Thermador	E22	Filter blocked
Samsung	5C / 5E	Drain error
Samsung	OC / 0C	Too much water, often from a drain or fill problem

Codes vary by model, so confirm in the manual for your exact model number.

What it costs to fix

Clearing a clog or a kinked hose often costs nothing but your time. A replacement drain pump runs about $100 to $250 nationally with parts and labor; our Naperville price is [PRICE]. Full numbers are on the dishwasher repair cost page.

When to call a technician

• The filter, disposal, sink and hose are all clear and it still won’t drain
• You hear humming or grinding at drain time
• Dirty water keeps flowing back in after it drains
• It shows a drain code that comes back after a reset
• You’d rather not disconnect hoses under the sink

Book online or call [PHONE]. The [FEE] diagnostic is credited to the repair. See our pricing and policies.

Not draining: common questions

Is it safe to leave standing water in the dishwasher?

For a day or two, yes, but it will start to smell and can attract bacteria. Bail it out and clean the filter. If you can’t get it to drain, turn off the power until it’s fixed.

Should I pour drain cleaner into the dishwasher?

No. Chemical drain cleaners can damage the pump, seals and plastic parts. Clean the filter by hand and clear the disposal instead.

Why does my dishwasher drain into the sink?

If water comes up in the sink or out of the air gap when the dishwasher drains, the shared drain or the air gap is clogged. Clear the disposal and the air gap first.

Can a dishwasher drain without a high loop?

It can, but without a high loop or air gap, dirty sink water can siphon back into the dishwasher, causing smells and dirty dishes. The hose should loop up under the countertop.

Reviewed by [TECH NAME], appliance technician. Last updated October 27, 2026.