Dishwasher Not Draining? 7 Causes and How to Fix Them
Standing water in the bottom of your dishwasher is the single most common dishwasher problem we see across Washington — and the good news is that most causes are simple. Work through these seven checks in order. If you get stuck, our techs at A One Dishwasher Repair WA fix drain issues same-day statewide: (253) 549-3002.
1. The Filter Is Clogged
Pull out the bottom rack and twist out the cylindrical filter assembly. If it's caked with food debris and grease, that's your problem — water can't reach the drain. Rinse it under hot water with a soft brush. This alone fixes maybe a third of "not draining" calls.
2. The Garbage Disposal Knockout Plug
Just had a new garbage disposal installed? The dishwasher drain hose connects to it — and installers routinely forget to knock out the disposal's drain plug. No plug removed = no drainage, ever. We see this constantly in kitchens across Washington after remodels.
3. Kinked or Clogged Drain Hose
The corrugated hose runs from the dishwasher to the disposal or sink drain. Pull the dishwasher out slightly (power off first) and check for kinks. Also verify the hose has a high loop — it should rise up under the countertop before connecting. No high loop = dirty sink water flows back into the dishwasher.
4. The Air Gap Is Blocked
That little chrome cylinder next to your faucet is the air gap. Pop its cap and clear any gunk. A blocked air gap causes slow draining and water backing into the sink.
5. The Drain Pump Is Dead
If everything above is clear and it still won't drain, the pump motor has likely failed — you'll hear a hum but no water movement, or nothing at all. Drain pumps are a wear item (5–8 years). Replacement is a routine same-visit repair for us.
6. The Check Valve Is Stuck
A small flapper valve keeps drain water from flowing back in. When it sticks shut, water can't get out. Quick part, quick fix.
7. Glass or Debris in the Pump
A shard of glass or a fruit pit in the drain pump impeller stops it cold. Don't reach in blind — pumps have sharp edges. This is a 20-minute pro job.
When to Call a Pro
If you've checked the filter, hose, air gap, and disposal connection and there's still standing water — it's the pump, the valve, or an electrical issue. That's our territory. Same-day appointments anywhere in Washington, $89 diagnostic waived with repair: (253) 549-3002.
Dishwasher Drain FAQs
Can I run my dishwasher if it's not draining?
No — you'll just add more water to the tub and risk overflowing onto your floor. Bail out the standing water and troubleshoot or call us.
Why does my dishwasher drain into the sink?
Missing or failed high loop / air gap. Dirty water is backflowing. Fix the loop — it's also a code requirement.
How much does it cost to fix a dishwasher that won't drain?
Filter/hose issues: minimal (often just the diagnostic). Drain pump replacement: typically $150–$280. See our 2026 Washington repair cost guide for the full breakdown.
For prevention, add a yearly maintenance tune-up to your routine — a clean filter and clear drain system stop most drain calls before they start.