Direct answer: If your dishwasher is noisy while draining, the usual cause is debris hitting the drain pump impeller or a partial blockage in the filter, sump, air gap, or drain hose. If the noise only shows up during drain and the tub empties slowly or leaves water behind, stay on the drain-path checks before assuming the pump is bad.
Most likely: Most often, a hard bit of food, glass, label scrap, or bone chip has made it past the dishwasher filter and is rattling around at the drain pump.
Pin down when the sound happens. A grinding or rattling only during drain points you toward the drain path. A wash-phase swishing or spray noise is a different problem. Reality check: a healthy dishwasher is never silent, but a harsh growl, grind, or rattling burst at drain time is not normal. Common wrong move: running cycle after cycle hoping it will clear itself usually just chews debris deeper into the pump.
Don’t start with: Don’t start by ordering a dishwasher drain pump just because the sound is loud. A lot of these turn out to be debris or a kinked drain hose.
A harsh grinding, clicking, or pebble-in-a-fan sound starts when the dishwasher begins pumping water out.
Start here: Start at the filter and sump area. Small debris in the dishwasher drain pump is the most likely cause.
You hear a steady motor hum during drain, but the tub empties slowly or not fully.
Start here: Look for a blocked dishwasher filter, clogged air gap, or restricted dishwasher drain hose before blaming the motor.
The dishwasher gets noisy at drain time and water burps or spits from the air gap on the sink deck.
Start here: The downstream drain path is restricted. Check the air gap and the dishwasher drain hose route to the sink drain or disposal.
The drain sound is louder than usual and comes with a hot electrical smell or repeated stalled buzzing.
Start here: Stop using the dishwasher. A seized dishwasher drain pump or wiring issue needs closer inspection.
This is the classic cause when the noise is sharp, sudden, and only happens during drain. Hard debris can rattle, grind, or jam the impeller.
Quick check: Remove the dishwasher filter and look into the sump for glass, seeds, bone chips, paper label scraps, or broken plastic.
A dirty filter can starve the pump, make it cavitate, and send extra debris toward the drain side. The sound is often more of a rough growl than a metallic grind.
Quick check: Pull the dishwasher filter and check for grease, soft food buildup, and standing dirty water under it.
When the pump has to push against a blockage, it gets louder and the drain sound can turn into a strained hum or gurgle. You may also see slow draining or water backing up at the sink air gap.
Quick check: Inspect the dishwasher drain hose for kinks and remove the air gap cap to check for packed debris if your sink has one.
If the drain path is clear and the same loud hum, growl, or grinding returns every drain cycle, the pump bearings or impeller may be worn.
Quick check: After cleaning the drain path, run a short cycle. If the noise is unchanged and clearly comes from the pump area, the dishwasher drain pump moves up the list.
Dishwashers make different normal sounds during wash, fill, and drain. You want to avoid chasing the wrong component.
Next move: You’ve narrowed it to the drain side, which keeps the next checks focused and cheaper. If the sound happens during wash, fill, or all the time, this page is no longer the best fit.
What to conclude: Noise only during drain usually points to debris, a restriction, or a failing dishwasher drain pump.
This is the safest and most common fix. A lot of loud drain noises come from junk sitting right where the pump picks it up.
Next move: Reassemble and test. If the drain noise is gone or much quieter, the problem was debris or a clogged filter. If the filter area is clean and the noise is still strong, keep going down the drain path.
What to conclude: A dirty dishwasher filter or debris in the sump is the most likely cause when the sound is new and sudden.
A partial blockage downstream makes the pump work harder and louder. This is especially common when the dishwasher drains into a sink air gap or disposal connection.
Next move: If the dishwasher drains faster and the noise settles down, the restriction was in the air gap or hose route. If the hose route is clear and the noise still comes from the dishwasher base, the pump itself becomes more likely.
Once the easy blockages are cleared, the remaining question is whether the dishwasher drain pump is damaged or just still obstructed deeper inside.
Next move: If the sound pattern clearly changed after cleaning, you likely removed most of the blockage and can recheck for anything left behind. If the same loud drain noise returns with a clear filter and hose path, plan on pump access or service.
At this point you should know whether you fixed a blockage, need a hose replacement, or are down to a pump problem.
A good result: The dishwasher should drain with a brief smooth pump sound, no harsh grinding, and little or no water left in the sump area.
If not: If a new hose or cleaned drain path does not change the sound, the dishwasher drain pump is the next likely repair.
What to conclude: You’ve ruled out the common cheap causes and narrowed it to the actual failed part or a repair that needs hands-on access.
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That usually means the problem is on the drain side, not the wash side. The most common causes are debris in the dishwasher drain pump area, a clogged dishwasher filter, a restricted dishwasher drain hose, or a blocked sink air gap.
Yes. A packed dishwasher filter can let sludge and small debris collect in the sump, which makes the pump work harder and sometimes sends debris into the impeller area. Clean the filter first before assuming the pump has failed.
A failing dishwasher drain pump often makes a steady loud hum, rough growl, or repeated grinding during the drain portion of the cycle. If the filter, sump, air gap, and hose are clear and the same noise keeps returning, the pump is a strong suspect.
That usually means the dishwasher is trying to push water through a restricted path after the air gap. The air gap itself may be clogged, or the dishwasher drain hose or sink-side connection may be restricted. If that is your main symptom, see /dishwasher-air-gap-spitting-water.html.
No. If the sound is harsh or new, stop and check the filter and sump first. Repeatedly running it can grind debris deeper into the pump or overheat a pump that is already struggling.
Not if the sound is clearly harsher than it used to be. A little pump noise is normal, but a new rattling, grinding, or strained hum usually means debris is still in the drain path or the dishwasher drain pump is wearing out.