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Dishwasher won't drain

Standing water looks worse than it usually is. The most common cause by far is a clogged filter that most owners have never been shown — free to clean in ten minutes. Work down the list before anyone talks about pump replacement.

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Select anything that matches and the checklist below reorders to fit. Not sure? Skip it.
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In Canadian homes, the most common cause to rule out is the filter — a twist-out cylinder and flat screen under the bottom spray arm that most owners have never been shown. Cut power at the plug or breaker first (some models hide a chopper blade in the sump), lift out the bottom rack, twist the filter free, and rinse it clean. Free, ten minutes, and the fix more often than everything else on this page combined.

Ranked from real-world failure data. The order updates as you select what you’re noticing above.

Likely causes, in the order to check them

Showing the typical order
Beginner-friendly Doable, with care Safety-critical Call a pro

visibilityHow to check

report Cut the power before you reach into the sumpUnplug the dishwasher or switch off its breaker before putting your hand into the bottom of the tub. Some models have a small chopper blade in the sump right under the filter, and the machine only needs a confused float switch to try to start with your fingers in there. Ten extra seconds, zero risk.
  1. Cut the power first: unplug the dishwasher (the plug is often reachable under the sink) or switch off its breaker.
  2. Slide out the bottom rack and look under the bottom spray arm for a round twist-out cylinder — that's the filter. Twist it counter-clockwise, lift it out, and lift out the flat screen beneath it.
  3. A mat of food scraps, grease, seeds, or a stray jar label on the screen is the whole story on most no-drain calls. Scoop any loose debris out of the sump opening while you're there.
buildNo tools schedule10 min

handymanHow to fix it

Rinse the filter and screen clean under hot water, scoop out the sump, reseat everything until it locks, and run a rinse cycle. Free, and worth repeating every month or two.

  1. Rinse the filter cylinder and flat screen under hot running water; an old toothbrush or dish brush shifts the grease film.
  2. With the power still off, wipe out the sump opening and fish out anything solid — glass shards, fruit pits, and toothpicks are the usual finds.
  3. Reseat the screen, twist the filter back in until it locks (a loose filter lets debris straight into the pump), restore power, and run a short rinse cycle to confirm it drains.
schedule15 min savingsusually free

visibilityHow to check

  1. Open the sink cabinet and follow the corrugated hose from the dishwasher. It should rise in a high loop secured near the countertop before dropping to the drain — a hose that sags flat, or one pinched by a garbage can or a pot, is the tell.
  2. If the hose ends at a garbage disposal, run the disposal for ten seconds with the water on — a packed disposal blocks the dishwasher's outlet at the same time.
  3. Start a drain cycle and put a hand on the hose. The pump humming with no pulse of water moving through the hose points to a blockage in the run.
buildflashlight schedule20 min

handymanHow to fix it

Disconnect the hose at the sink end with a bucket and towels ready, clear the clog, then re-secure the high loop so it can't sag back.

  1. Bail most of the standing water out of the tub first — whatever is in the hose is coming out when you open it. Bucket under the connection, towels down.
  2. Squeeze or unscrew the hose clamp at the disposal inlet or drain tee and work the hose off. Let it drain into the bucket.
  3. Clear the clog: straighten out any kink, then flush the hose into the bucket or work a flexible drain brush through it. Sludge usually sits at the low, flat spots and at the very end.
  4. Reconnect and clamp the hose, then secure the high loop up near the countertop (a zip tie or the clip that came with the machine). The loop is what stops sink water from siphoning back into the dishwasher. Run a rinse cycle and watch the connection for drips.
schedule40 min savings$0–25

visibilityHow to check

report Unplug it before the pump testThis check mixes standing water and electrical connectors, so the machine must be unplugged or its breaker off — not just cancelled at the panel — before you remove any panel or touch the pump. If pulling a dishwasher out and metering a pump isn't your idea of a good Saturday, that's a fine place to stop: this is a routine, fairly quick visit for an appliance tech.
  1. Bail the standing water, then start a drain cycle and listen low at the front of the machine: a steady hum with no water moving points to the pump — jammed, or burned out.
  2. Cut the power, remove the filter and screen, and feel carefully around the sump opening. A shard of glass or a fruit pit jamming the impeller is the common happy ending — clear it and test again.
  3. To test the pump itself: unplug the machine, remove the kick panel (on many models the pump is reached from underneath or by pulling the unit out), disconnect the pump's wiring connector, and check across the pump terminals with a multimeter set to ohms. An open reading (OL) points to a dead winding and a replacement pump.
buildmultimeterbuildscrewdriver schedule45 min

handymanHow to fix it

With the machine unplugged and the water bailed, swap the drain pump for the exact part for your model — most twist or screw onto the sump from below — then reconnect the wiring and hose and test a drain cycle before pushing the unit back in.

  1. Unplug the machine (or switch off its breaker), shut the water supply valve under the sink, and bail the tub as dry as you can.
  2. Remove the kick panel; on many models you'll also disconnect the supply line and drain hose and pull the unit out to lay it back or reach underneath. Photograph the connections as you go.
  3. Disconnect the pump's wiring connector and hose, then release the pump — most twist a quarter-turn or come off with two or three screws. A towel catches the cupful of water that follows.
  4. Seat the new pump with its seal, reconnect the wiring and hose, and run a drain cycle while the unit is still accessible — watch the pump for leaks before you push everything back and re-level the feet.
schedule90 min savings$40–130
Dishwasher drain pumpMatch your model number — the sticker is on the door edge or tub rim; pumps are model-specific
gavel Check your province first AB: homeowner may do this · BC: homeowner may do this · ON: homeowner may do this · PE: homeowner may do this · QC: homeowner may do this
Repairing a cord-and-plug appliance with the power disconnected is appliance repair; no fixed wiring is altered. REVIEW: confirm no province treats hardwired-dishwasher disconnection as regulated electrical work.

visibilityHow to check

  1. Under the sink, find where the dishwasher's drain hose meets the disposal: a small side inlet near the top of the disposal body.
  2. With a towel ready, loosen the clamp and slip the hose off the inlet, then shine a flashlight in. An intact plastic disk sealing the opening means the knockout plug was never removed.
  3. No disposal? Check the air gap instead — the small chrome cylinder on the sink deck. Pop its cap and clean out any debris packed inside.
buildflashlight schedule10 min

handymanHow to fix it

warning Unplug the disposal before reaching inYou'll be putting a screwdriver — and then tongs — into the disposal's grinding chamber. Unplug it or switch off its breaker first, and use tongs or pliers to retrieve the plastic disk, never fingers. If the disposal is hardwired with no plug, the breaker is your off switch.

Unplug the disposal, punch the plastic knockout plug into the grinding chamber with a screwdriver and a tap of a hammer, fish the loose disk out, and reconnect the hose.

  1. Unplug the disposal (or switch off its breaker if it's hardwired). You're about to reach into it.
  2. Seat a flat screwdriver against the plastic plug through the inlet and give it a firm tap or two with a hammer — the disk breaks free and falls into the grinding chamber.
  3. Fish the loose plastic disk out of the chamber with pliers or tongs — not fingers — so it can't rattle around in the grinder later.
  4. Reconnect and clamp the drain hose, restore power, and run a drain cycle to confirm the water flows.
schedule15 min savingsusually free

visibilityWhat you can spot yourself

  1. Run the kitchen sink hard for a minute. Slow draining, gurgling, or water rising points to a clog downstream of both the sink and the dishwasher.
  2. Start a dishwasher drain cycle and watch the sink: dirty water burping up into the basin (or the air gap spitting onto the counter) says the dishwasher is pumping fine — the water just has nowhere to go.
buildNo tools schedule5 min

handymanHow to fix it

Treat it as a sink-drain clog, not a dishwasher fault: empty and clean the P-trap under the sink (bucket first), run hot water, and retest. If backups recur or other fixtures gurgle too, the blockage is deeper in the branch or main — that's a plumber's auger, not a dishwasher part.

schedule30 min savings$0–15
sort

Why the list is in this order

We don’t sort by likelihood alone. We sort the way a good, honest tradesperson thinks: rule out the free, safe, common causes first. That’s why the cheap checks outrank the expensive repairs — and why anything dangerous gets a hard stop instead of a pep talk. The order exists to save you money, not to sell you anything.