Fix a Dishwasher That Won't Drain
An inch of grey water sitting in the bottom of the dishwasher looks like a dead pump and usually isn't. Work from the filter outward — most no-drain dishwashers are fixed with a scrub brush and ten minutes, no parts at all.
What is actually broken
A dishwasher drains through a filter, out a hose, and into the sink drain or garbage disposal. Anything that blocks that path leaves water in the tub: a filter matted with grease and labels, food sludge in the air gap on the sink, a kinked or clogged drain hose — or, the classic, a brand-new garbage disposal whose dishwasher inlet plug was never knocked out, so the dishwasher has been pumping against a wall. Only after the whole path is proven clear does a failed drain pump become the likely answer.
Safety first
- Kill the power at the breaker before reaching into the sump or pump area — and fish carefully: the number-one thing hiding in dishwasher sumps is broken glass.
- Standing dishwasher water is greywater — gloves on, and don't use the 'clean' dishes from the interrupted load without re-washing.
- Mop up before you work: a slow leak plus a pulled dishwasher plus a wet floor is how a $0 fix becomes a floor repair.
The fix, step by step
1 Clear the tub and scrub the filter
Cancel the cycle, bail the standing water with a cup into the sink, and pull the bottom rack. The filter is the mesh cylinder or flat screen in the floor of the tub — twist or lift it out and scrub it under the tap with a brush and a drop of dish soap. On many machines this alone restores draining; filters clog invisibly under a film of grease.
Tip: While the filter is out, wipe the sump beneath it and pick out any debris, labels, or bones with a gloved hand — carefully, feeling for glass edges first with a spoon, not your fingers.
2 Check the air gap or high loop
If your sink has a little chrome cap beside the faucet, that is the air gap — pop the cap and cover off and pull out any food sludge plugging it. No air gap? The drain hose should loop up high under the counter (a 'high loop'); if it has fallen flat, draining slows and sink water can back-flow. Re-secure it up high with a strap.
Tip: Run the sink disposal for 15 seconds with cold water while you are here — a half-full disposal backs up the shared drain path.
3 Rule out the disposal knockout plug
Was a new garbage disposal installed around when the draining problem started? Then suspect the knockout: disposals ship with a plastic plug sealing the dishwasher inlet, and if it was never knocked out, the dishwasher physically cannot drain. Power off, remove the drain hose from the disposal inlet, and look inside — a solid plastic disc is the plug. Knock it out with a screwdriver and hammer, fish the disc out of the disposal, and reconnect.
Tip: This is the single most-missed diagnosis in the trade — service techs charge full call-out fees to knock out a 10-cent plug.
4 Flush the drain hose
With power off, disconnect the drain hose at the sink/disposal end (bucket ready — it holds water) and check for clogs at the fitting. Blow through it or flush it with a garden hose outside; a hose that is kinked behind the machine or chewed flat gets replaced, not cleared. Reconnect with the clamp snug.
Tip: Take a photo of the hose routing before disconnecting anything. The high loop position matters when it goes back.
5 Test the drain pump last
Power back on, pour a gallon of water into the tub floor, and start a cancel/drain cycle. You should hear the pump hum and see the water leave. A hum with no flow and a clear path means something is jammed in the pump impeller (power off, access from inside the sump on most models). Total silence from a pump with power is a dead pump — a model-specific part, about $25–$45, and a fair DIY swap; boards and motors beyond that are pro territory.
Tip: Not sure which sound is the pump? Snap a photo of the standing water and your model plate into the ClickTheFix app — the diagnosis will name the likely part before you order anything.
Stop and call a pro if…
Call an appliance tech or plumber if water is leaking under the machine onto the floor (pump seals and inlet valves leak differently than clogs), if the dishwasher trips the breaker, or if the drain path is clear, the pump runs, and it still won't drain — that points at the control board.
Your work, your responsibility
If you do this repair yourself: you attempt it entirely at your own risk. This guide is general information, not professional advice, and it can be wrong or incomplete. ClickTheFix is not responsible for injury to you or anyone else, or for damage to your property, that results from following — or misfollowing — this guide. Follow the safety warnings, use proper protective gear, follow the manufacturer's instructions and your local codes, and stop if any step is beyond your skill or comfort.
If a contractor does the work: any contractor you hire is an independent professional working under an agreement between you and them alone. ClickTheFix does not provide repair services, does not supervise or control their work, and does not guarantee or warranty it. ClickTheFix is not liable for a contractor's errors, omissions, poor workmanship, property damage, or injuries.