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Dishwasher won't drain — what to check

Standing water in the bottom is almost always a clog, and most are DIY. In order: clean the filter at the bottom, check the drain hose for kinks or blockage, clear the air gap if you have one, and — if you just installed a garbage disposal — make sure its drain plug (knockout) was removed. Check the safety note below first if there's water on the floor near an outlet.

First, a safety check — is any of this true right now?

No hazard flagged — the diagnostic steps below are appropriate. If any of the above changes, stop and follow the safety guidance.

The clog checklist, cheapest first

1) Filter: twist out the cylindrical filter in the tub floor and rinse away food and grease. 2) Drain hose: check it isn't kinked and isn't clogged where it meets the disposal or sink drain. 3) Air gap: the little cylinder on the sink — pop the cap and clear debris. 4) Disposal knockout: a brand-new disposal ships with a plug that must be knocked out, or the dishwasher can't drain into it.

Scoop out standing water first with a cup and towel so you can work.

When it's worth a pro (or a replacement)

If it still won't drain after those, the drain pump or a control fault is likely — a repair call. A dishwasher lasts about 9 years (InterNACHI); if yours is near that and the repair is pricey, weigh replacement. See common repair costs.

When to call a professional

  • • Water on the floor near an outlet — follow the safety step (cut power/supply) before touching it.
  • • It won't drain after clearing the filter, hose, air gap, and disposal — likely the drain pump.

Common questions

Is standing water in a dishwasher normal?
A small amount in the sump can be; a full pool of dirty water after a cycle is not — it's a drainage clog to clear.
Why did it stop draining after a new disposal?
Almost always the disposal's drain knockout plug wasn't removed during install. That's the first thing to check.

Sources

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