Repair guide
Dishwasher not draining
Updated 30 Sep 2026 · AR Logic LLC · 3 sources
Rarely an emergency
Standing water after a cycle is almost always a blockage, not a broken dishwasher: a clogged filter, a kinked or low drain hose, or — on a new install — the garbage disposal’s knock-out plug that was never removed. Check those three before calling anyone; the drain pump is the usual culprit only when all three are clear.
Is a dishwasher that won’t drain an emergency?
Rarely. Standing water in the tub can wait while you check the filter and the drain hose. It becomes urgent if water is leaking onto the floor or reaching outlets or cords: switch off the dishwasher’s breaker and turn off its water supply under the sink.
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Managers: set it up for your buildings →What to check, in order
Clean the filter
Most dishwashers made in the last fifteen years have a manual filter under the lower spray arm. Twist it out, rinse it under the tap and scrub the fine mesh. A clogged filter is the most common reason water stays in the tub [1].
Look at the drain hose
Under the sink, follow the ribbed hose from the dishwasher to the disposal or drain. It must not be kinked or crushed behind the cabinet, and it needs a “high loop” — raised and fastened up near the underside of the counter — or an air gap, so dirty sink water cannot run back into the tub [1][3].
New disposal? Check the knock-out plug
A new garbage disposal ships with a plastic plug sealing its dishwasher inlet. If the dishwasher was just connected to a new disposal and has never drained, the plug is almost certainly still there; it has to be knocked out from inside the inlet [1][2][3].
Run the disposal and clear the sink drain
The dishwasher drains through the same pipe as the sink. Run the disposal with cold water; if the sink itself drains slowly, the clog is in the sink drain, not the dishwasher.
Clear the air gap
If there is a small chrome cap on the sink deck, pull the cover off and clear any debris inside. A blocked air gap often shows as water spurting from it during the drain.
Listen to the drain pump
Start a drain (on most models, cancel the cycle). A hum with no water moving points at a jammed or failed pump; broken glass or a fruit pit in the sump is a common jam. Brands show this as a code: Bosch E24/E25, LG OE, Whirlpool and KitchenAid a flashing drain light [2][3].
By brand
Safety first
- Switch off the dishwasher at its breaker before reaching into the sump or unclamping a hose.
- Scoop or sponge the water out before removing the filter; the tub can hold a gallon or more.
- Watch for broken glass in the sump.
When to call a pro
Call an appliance technician if the filter, hose, disposal and sink drain are clear and the pump still hums without moving water, or if water is leaking under the machine.
What to photograph
For the Triage Profile, photograph the open tub with the lower rack pulled out, so the standing water and the filter area are visible. One clear photo in good light is enough; the Triage Profile says what it is, how urgent it is (emergency, today, this week or whenever), and which trade to call.
Questions people ask
Why is there always a little water in the bottom?
Many dishwashers leave a small amount of clean water in the sump to keep the pump seal wet. An inch or more of dirty water is a drain problem.
Can I use drain cleaner in a dishwasher?
No. Chemical drain cleaners can damage the pump and hoses. Clean the filter and clear the hose instead.
Sources
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