Fix it
Why won't my dishwasher drain?
Standing water in a dishwasher is a blocked path more often than a broken pump — and the path has exactly four checkpoints: the filter, the drain hose, the air gap or high loop, and the connection into the sink drain.
What it usually is
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A clogged internal filter and sump
Modern dishwashers have a cylindrical filter at the tub floor that most owners have never removed. Food film and glass shards accumulate until water simply cannot reach the pump.
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The drain hose kinked or blocked
The corrugated hose to the sink pinches behind the unit or clogs at its narrowest point — commonly right at the connection into the disposal or drain tee.
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A disposal connection still wearing its knockout plug
After a disposal replacement, the dishwasher inlet plug must be knocked out; a forgotten plug blocks drainage completely. New-disposal-then-no-drain is this, every time.
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A failed drain pump or its check valve
If the machine hums at drain time with clear paths, or is silent when it should pump, the pump or its one-way valve has failed.
What you can check yourself
Twist out the filter, rinse it, and clear the sump beneath (wear a glove — glass hides there). Bail the tub, pull the unit forward and straighten the hose. Run the disposal briefly — it clears the shared connection. After any disposal work, verify the knockout. Then run a rinse cycle and listen for the pump.
When it’s a job for a pro
A silent or humming pump with clear paths is a part replacement — moderate cost, awkward access under the tub. Repeated clogs deserve a look at hose routing and the high loop, which prevents dirty sink water from back-feeding.
Filter and hose clearing is $0 DIY; a drain pump typically runs $150 to $350 installed. The knockout fix is a screwdriver and thirty seconds.
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