Household Atlas
Household Atlas
Dishwashers

Dishwasher Not Draining? Find the Clog in Five Places

A dishwasher pumps its water through a short, narrow path: filter, sump, pump, hose, sink drain. A clog anywhere along it leaves a pool in the tub. Work along the path and you will usually find it.

By Household Atlas Editors Updated 4-minute read 3 sources

Quick answer

Start with the filter at the bottom of the tub: twist it out, rinse it and clear the sump beneath it. Then run the garbage disposal, check the drain hose under the sink for kinks, and clean the air gap cap on the sink if you have one. If you just installed a new disposal, its knockout plug may still be in place. A pump that hums without draining is jammed or failing.

Difficulty
Easy DIY
Check first
The filter and sump at the bottom of the tub
Normal
A little clean water in the sump, not a pool over the tub floor
Never use
Chemical drain cleaner in the dishwasher
Technician job
Drain pump, control board, hard-wired electrical work
On this page

At the end of each wash and rinse, a small pump at the bottom of the dishwasher pushes the water out through a hose to the sink drain, an air gap or the garbage disposal. Food that gets past the filter, a kink in the hose or a clog in the sink can stop that flow. The fix is almost always cleaning, not parts.

Before you start

  • Turn off the power at the circuit breaker, not just the control panel. Many dishwashers are hard-wired.
  • Bail out the water with a cup into a bucket, then use a turkey baster or sponge for the last of it. Lay towels in front of the door.
  • Do not pour drain cleaner into the dishwasher. It can damage seals and the pump, and it will be in the water you handle next.

Work along the drain path

  1. Clean the filter.

    Remove the lower rack. On most models you twist the upper filter counterclockwise and lift it out, then lift out the coarse filter beneath. Rinse both under warm water with a soft brush. Do not use scouring pads, which tear the mesh.

  2. Clear the sump.

    With the filters out, shine a flashlight into the well below. Pull out seeds, labels, broken glass, bones and toothpicks. Hard debris here is what jams the drain pump.

  3. Run the garbage disposal.

    Most dishwashers drain into the disposal. If it is full of food, the dishwasher cannot drain through it. GE recommends running the disposal before every dishwasher cycle. If the disposal was just installed, make sure its knockout plug was removed (see below).

  4. Check the drain hose under the sink.

    Look for kinks, crushed sections or a sag. The hose should rise in a high loop fastened to the underside of the counter, or connect to an air gap. Loosen the clamp at the disposal or sink tailpiece, check the hose end for gunk, and flush the hose with water.

  5. Clean the air gap.

    If there is a small chrome cylinder on the back of the sink, pull or twist off its cap and clear the debris inside. Water spurting from it during a drain means the clog is farther down.

  6. Check the sink drain.

    If the sink itself drains slowly, the dishwasher has nowhere to go. Clear the sink trap or call a plumber.

  7. Run a rinse cycle and listen.

    You should hear the pump and see the water go. If it hums and nothing moves, or makes no sound at drain time, the pump or controls need service.

What the water tells you

What you see Likely cause Next step
A little water just above the filter Partial clog in the filter, sump or hose Clean filters and sump; check the hose
Water nearly up to the door Severe blockage, or the pump is not running Check hose, disposal knockout and pump
Water backs up out of the air gap Clog between the air gap and the drain Clear that hose and the sink drain
Pump hums, no water moves Jammed impeller or failing pump Look for hard debris in the sump; then service
Suds left in the tub Wrong detergent (dish soap) or too much Use dishwasher detergent only; run a rinse
New install never drained Disposal knockout plug in place, or no high loop Remove the plug; fix the hose routing

The knockout plug. A new garbage disposal ships with a solid plastic plug inside its dishwasher inlet. It must be knocked out with a screwdriver and hammer, and the loose piece fished out of the disposal, before the dishwasher hose is connected. Both Whirlpool and GE list a forgotten plug as a cause of a dishwasher that will not drain at all.

Why the high loop matters

Without a high loop or air gap, dirty water from the sink and disposal can flow back down the hose into the dishwasher, and the dishwasher can siphon its own water out mid-cycle. GE’s instructions specify the loop height in each model’s installation guide. If someone recently worked under the sink, check that the hose is still clipped up high.

Keep it draining

  • Scrape plates into the trash; a rinse is not needed, but bones, seeds and labels should not go in.
  • Clean the filter on the schedule in your manual, more often if you run the dishwasher daily.
  • Run the disposal before starting the dishwasher.
  • Use only detergent made for dishwashers.

When to call a technician

If the filter, sump, hose, air gap and sink drain are all clear and the dishwasher still will not drain, the drain pump, a drain valve on older models, or the control is likely at fault. Dishwashers are often hard-wired and sit on a water supply, so pump and control work is usually a service call. InterNACHI puts typical dishwasher life at about 9 years; on an older machine, the repair or replace calculator helps you decide.

Bottom linePower off, bail out the water, then clean along the path: filter, sump, disposal, hose, air gap, sink drain. New install? Check the disposal knockout plug and the high loop. A humming pump that moves no water needs a technician.

Frequently asked questions

Is some water in the bottom of a dishwasher normal?

A little clean water in the sump area under the filter is normal on many models; it keeps seals from drying out. GE says that on its models without an ultra-fine filter, 1 to 2 cups of clean water covering the bottom is normal. Dirty water, or water that covers most of the tub floor, is not.

Why does my dishwasher drain into the sink?

If water comes out of the air gap, the small chrome cap on the back of the sink, the blockage is downstream: in the hose from the air gap to the disposal or drain, or in the sink drain itself. Clean the air gap and clear that hose or the sink trap.

Can I use Drano or baking soda and vinegar to unclog a dishwasher?

Do not put chemical drain cleaners in a dishwasher; Whirlpool and GE both warn against it because they can damage parts and create a hazard if you later open the drain. Mechanical cleaning of the filter, sump and hose is safer and more effective.

Why won’t my new dishwasher drain?

Two installation mistakes cause most cases: a garbage disposal knockout plug that was never removed, and a drain hose with no high loop or air gap. Check both before calling for service.

My dishwasher hums but won’t drain. What is wrong?

A steady hum with no water moving usually means the drain pump impeller is jammed by debris such as glass or a seed, or the pump has failed. With power off at the breaker, remove the filter and look into the sump for anything hard. If it is clear, the pump likely needs a technician.

Sources

  1. Dishwasher Not Draining: How to Diagnose and Fix the Problem Whirlpool
  2. Dishwasher: Not Draining GE Appliances
  3. Standard Estimated Life Expectancy Chart for Homes International Association of Certified Home Inspectors (InterNACHI)

First published October 7, 2026. Last reviewed October 7, 2026. Spot an error? Tell us and we will check it against the source.

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