Sour or rotten-food smell when you open the door
The odor is strongest near the bottom rack or filter area, especially after the dishwasher sits closed overnight.
Start here: Start with the filter, sump, and lower spray arm area.
Dishwasher odor troubleshooting
Dishwasher Smells Bad
Direct answer: A bad dishwasher smell usually comes from trapped food sludge in the filter area, standing water in the sump, or dirty water backing in through the drain path. Start with the inside of the tub and the drain route before assuming a failed part.
Most likely: The most likely cause is a dirty dishwasher filter or debris packed around the sump and lower spray arm base.
Separate the smell first. A sour or sewer smell points to food residue or drain-path trouble. A hot plastic or electrical smell is a different problem and should be treated as a safety issue. Reality check: most smelly dishwashers need a deep clean in the right spots, not a new machine. Common wrong move: running bleach or strong cleaner through a dishwasher that still has grease and food packed in the filter area.
Don’t start with: Don't start with deodorizer pods or random parts. They can mask the smell for a day and leave the real buildup in place.
If the smell is sour, swampy, or like old dishwater,check for standing water, a slimy filter, and debris under the bottom spray arm first.
If the smell is burnt, sharp, or like hot plastic,stop using the dishwasher and treat it as a separate overheating or electrical problem.
Last reviewed: 2026-04-04
What kind of dishwasher smell are you dealing with?
Sewer smell from the dishwasher
The smell is more like drain gas or dirty sink water than food, and it may get worse after using the sink.
Start here: Start with the drain hose routing, sink air gap if you have one, and signs of sink water backing toward the dishwasher.
Musty smell after a cycle
Dishes may come out mostly clean, but the tub smells damp and stale after the cycle ends.
Start here: Start with the filter, door gasket folds, and whether water is left in the sump after the cycle.
Burning or hot plastic smell during a cycle
The smell shows up while running, not just when the door is opened, and may come with unusual heat or noise.
Start here: Stop here and treat it as a separate overheating or electrical issue, not a cleaning problem.
Most likely causes
1. Food sludge packed in the dishwasher filter and sump
This is the most common source of a bad smell. Bits of food, grease, paper labels, and soft debris collect below the lower rack where rinse water keeps them wet.
Quick check: Pull the bottom rack, remove the dishwasher filter if your model has one, and look for slime, gray paste, or trapped food in the sump opening.
2. Dirty water sitting in the bottom of the dishwasher
If the dishwasher is not draining fully, the leftover water turns sour fast and the smell comes back even after a rinse cycle.
Quick check: After a completed cycle, check the tub floor. A small clean puddle in the sump area can be normal, but visible dirty standing water is not.
3. Drain-path problem letting sink water or odor back in
A low drain hose loop, clogged air gap, or partial blockage can let nasty sink water wash back toward the dishwasher.
Quick check: Run the kitchen sink, then sniff near the dishwasher tub and check whether the drain hose rises high under the counter before dropping to the sink drain or disposal.
4. Buildup on the dishwasher spray arms, door gasket, and tub seams
When the filter is only mildly dirty, odor often hides in the spray arm holes, around the door seal folds, and along the lower lip of the tub.
Quick check: Wipe the door gasket and inspect the spray arm holes for grease, seeds, paper, or white mineral crust trapping residue.
Step-by-step fix
Step 1: Make sure this is a cleanup problem, not a heat or electrical smell
Bad odors and burning odors get confused all the time. You want to separate a dirty dishwasher from an unsafe one before you start taking anything apart.
- Open the dishwasher and smell near the tub opening before running it again.
- If the odor is sour, musty, rotten, or sewer-like, continue with the next step.
- If the odor smells burnt, like hot wiring, melting plastic, or overheated rubber, stop using the dishwasher.
- Look for obvious melted plastic on the heating area or a utensil that may have fallen onto a hot surface.
Next move: If you confirm it's a food, mildew, or sewer smell, move on to the cleanup and drain checks. If the smell is clearly burnt or electrical, do not keep testing cycles to 'see if it clears up.'
What to conclude: A dirty-water smell usually comes from residue or drain trouble. A burning smell points to a different failure and needs a safer diagnosis path.
Stop if:
- You smell burning insulation, melting plastic, or see smoke.
- The dishwasher trips a breaker or shuts off unexpectedly.
- You find a scorched wire, melted component, or heat damage beyond a stray plastic item.
Step 2: Check for standing water and clean the dishwasher filter area thoroughly
This is the highest-payoff step on a smelly dishwasher. Most odor starts in the wet debris packed around the filter and sump.
- Turn off power to the dishwasher before reaching into the sump area.
- Pull out the bottom rack.
- Remove the dishwasher filter and any coarse screen pieces that come out without forcing them.
- Wash the dishwasher filter with warm water and mild dish soap. Use a soft brush only if needed.
- Wipe sludge, food bits, and grease from the sump opening, filter well, and the floor of the tub.
- Remove labels, glass chips, bones, or other debris carefully if you can reach them safely.
Next move: If the filter area was dirty and the smell drops sharply after cleaning, you've likely found the main source. If the filter area was fairly clean or the smell returns fast, keep going and check the drain path next.
What to conclude: Heavy slime or trapped food strongly points to routine buildup. Dirty standing water points to a drainage issue feeding the odor back.
Step 3: Clean the spray arms, door gasket, and lower tub seams
Odor often lingers in places homeowners skip. Even after the filter is cleaned, grease and food paste can stay trapped where rinse water doesn't flush well.
- Inspect the lower dishwasher spray arm for clogged holes, stuck debris, or greasy film.
- If the spray arm is removable without force, take it off and rinse it out under warm water.
- Use a toothpick or similar non-metal pick gently to clear blocked spray holes if needed.
- Wipe the dishwasher door gasket folds, the bottom door edge, and the lower lip of the tub with warm water and mild soap.
- Clean around the hinge-side corners where residue tends to hide.
Next move: If the smell fades after these hidden surfaces are cleaned, the dishwasher likely had residue buildup rather than a failed component. If the odor still reads more like sewer or dirty drain water, move to the drain hose and sink-side checks.
Step 4: Check the dishwasher drain path for backflow or trapped sludge
A dishwasher can smell bad even when the tub looks clean if dirty sink water is washing back through the drain hose or an air gap is clogged.
- Look under the sink and trace the dishwasher drain hose.
- Make sure the dishwasher drain hose rises high under the counter before connecting to the sink drain or disposal.
- If your sink has an air gap on the countertop, remove its cap and check for gunk inside.
- Look for kinks, sags full of dirty water, or greasy buildup at the dishwasher drain hose connection point.
- If the hose is easy to remove and you are prepared for water spillage, flush or clean the hose only after shutting off power to the dishwasher and protecting the cabinet area.
Next move: If you find a clogged air gap, a sagging hose, or obvious sludge in the drain hose, correcting that usually fixes recurring sewer smell. If the hose routing is correct and the smell still comes back quickly, the problem may be a deeper internal drain issue or repeated sink-side backup.
Step 5: Run a hot cleanup cycle, then decide whether a part is actually justified
Once the real residue is removed, a final hot cycle tells you whether the smell was simple buildup or whether a repeat problem points to a worn dishwasher part.
- Reassemble the dishwasher filter and spray arm correctly.
- Run hot water at the kitchen sink first so the dishwasher starts with hot water.
- Run the hottest normal wash cycle with the dishwasher empty.
- If you want a mild follow-up cleaner, use one simple option only, such as a dishwasher-safe cleaning cycle with vinegar placed in a bowl on the top rack. Do not mix cleaners.
- After the cycle, open the door and check for odor, leftover water, and whether the tub smells clean after drying for a few hours.
- If the smell returns mainly after sink use or you keep finding dirty water in the bottom, plan on correcting the drain hose or sink-side backflow issue rather than guessing at internal parts.
A good result: If the odor is gone and the tub stays clean-smelling after drying, the fix was buildup removal and drain-path cleanup.
If not: If odor returns within a day or two and you keep seeing physical signs like a torn gasket, cracked filter, or sludge trapped in a damaged hose, replace only the part that matches what you found.
What to conclude: A dishwasher that smells clean after a hot cycle usually needed maintenance, not parts. A quick return of odor means something is still trapping residue or letting dirty water back in.
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FAQ
Why does my dishwasher smell like sewer?
A sewer smell usually means dirty water or drain odor is getting back toward the dishwasher. The usual culprits are a clogged air gap, a low or sagging dishwasher drain hose, or sink-side drainage trouble. Start under the sink, not with random dishwasher parts.
Can a dirty dishwasher filter really make the whole kitchen smell?
Yes. A dishwasher filter packed with wet food sludge can stink badly, especially after the door stays closed for hours. When you open the door, that trapped odor comes out all at once.
Is vinegar safe to use in a smelly dishwasher?
Usually yes as a simple follow-up cleaning step after you remove food debris and sludge first. Use one mild cleaning approach only, and do not mix vinegar with other cleaners. Vinegar will not fix a clogged drain hose or standing dirty water by itself.
Why does the smell come back right after I clean the dishwasher?
If the smell returns fast, something is still feeding it. The most common reasons are dirty water left in the bottom, sludge trapped in the dishwasher drain hose, or sink water backing toward the dishwasher after sink use.
Should I replace the pump if my dishwasher smells bad?
Not based on smell alone. A bad smell is much more often caused by residue or drain-path trouble than by a failed pump. Only move toward deeper internal diagnosis if you also have poor draining, unusual noise, or repeated standing water after the simple checks are done.