Quick answer: A dishwasher smell almost always starts in the filter. Most dishwasher smells come from food trapped in the filter, under the spray arms or in the drain hose. Clean the filter first, because it accounts for the majority of cases. A smell of sewage or drains that returns immediately after cleaning is different: that is waste water coming back into the machine because the drain hose has no high loop. A burning smell is electrical and means stop using it.
Key Takeaways
- Filter first, always. It is under the bottom rack and it lifts out with a quarter turn.
- Egg and fish smells are trapped protein. Wet dog is usually biofilm in the hose.
- Sewage that comes straight back after a clean is drain hose routing, not hygiene.
- Standing water in the bottom of the tub turns any smell into a worse one within a day.
What each dishwasher smell tends to mean
Smell to cause
| Smell | Usual source | What fixes it |
|---|---|---|
| Rotten eggs, sulphur | Trapped egg or dairy protein in the filter | Clean filter and spray arms |
| Fish | Protein residue, or a failing motor winding | Clean first. If it persists, technician |
| Wet dog, musty | Biofilm in the drain hose and sump | Deep clean, hot cycle with cleaner |
| Sewage, drains | Waste water siphoning back in | High loop in the drain hose |
| Stagnant water | Machine not draining fully | Filter, then pump |
| Burning, hot plastic | Motor, heater or wiring | Stop using it. Technician |
Start with the filter
Pull out the bottom rack. In the floor of the tub there is a cylindrical filter, usually marked with an arrow or a padlock. Twist it anticlockwise and lift it out, then lift out the flat mesh screen underneath.
What comes out is often unpleasant, and that is the point. Rinse both parts under hot water, scrub the mesh with an old toothbrush, and refit them making sure the tower locks into place.
While the filter is out, look into the recess beneath it. That is the sump, and food that gets past a loose filter collects there. A cloth and hot water is enough.
The full routine, including the spray arms, is in how to clean a dishwasher.
Then the spray arms and the door
Take the spray arms off and run water backwards through the jets. Blocked jets hold food, and they are also why the top rack often comes out dirty.
Wipe the inner face of the door, especially the bottom lip below the level the water reaches. Grease builds there and never gets washed. Run a cloth around the rubber door seal at the same time.
Then run the machine empty on its hottest cycle with a dishwasher cleaner, or a cup of white vinegar on the top rack. That handles what is left in the hoses and the sump.
The smell that comes straight back
Here is the test that saves people cleaning the same machine repeatedly.
Do a full clean. Filter, arms, door, hot cycle. Then use the machine normally for a day or two.
A hygiene smell improves noticeably and stays improved for weeks. A smell that is back by the next morning, particularly if it smells like drains rather than old food, was never inside the machine.
In that case, pull the dishwasher out and look at where the drain hose goes. It needs to rise into a high loop above the level of the tub before it drops to the waste connection, or it needs an air gap fitting. Without that, dirty water from the sink drain flows back down into the dishwasher every time you empty the sink, and sewer gas travels up the same path.
This turns up most often after a kitchen renovation, after a sink or waste disposal is replaced, or after the machine has been pulled out and pushed back. It is a plumbing job rather than an appliance repair, and it is fair to say so.
Standing water makes everything worse
A shallow film of water in the filter recess is normal and keeps the seal wet. Water lying across the floor of the tub is not.
Water that sits between cycles goes stagnant within a day, and it will overpower any amount of cleaning. If the machine is not draining fully, start with the filter, then look at the drain hose, then the pump. Until it drains properly the smell will keep coming back.
Habits that keep it away
Scrape plates rather than rinsing them. Modern detergent needs something to act on, but bones, seeds, labels and eggshell should never reach the filter.
Run the machine often enough. A dishwasher used twice a month sits damp and warm in between, which is ideal for biofilm. If you genuinely use it rarely, run a short hot cycle empty every couple of weeks.
Leave the door ajar after the cycle. It is the same principle as a front loading washer, and it does more than any cleaner.
Clean the filter monthly. That one habit prevents most of what is on this page.
When it is a fault
Cleaning will not resolve any of these, and they are worth a diagnosis rather than another bottle of cleaner:
- Water remains in the tub after every cycle, with a clean filter.
- The water never gets hot, so detergent does not dissolve and grease is not cut.
- A fishy or hot plastic smell during the cycle rather than between cycles.
- An error code that returns after switching the machine off and on.
When you book, leave the machine as it is. Do not unplug it and do not pull it out of the cabinet to investigate first. A fault still present when we arrive is a fault we can usually deal with in one visit.
Frequently asked questions
Why does it smell like wet dog?
Biofilm, which is a bacterial layer that forms in the drain hose and sump on machines run mostly on eco or short cycles at low temperatures. A hot cycle with a proper dishwasher cleaner is what shifts it.
Can I use bleach in a dishwasher?
Not in stainless steel tubs, and never combined with vinegar. A dedicated dishwasher cleaner or citric acid is safer and works better on the film that actually holds the odour.
The smell is only when I open it after a cycle. Is that normal?
A warm, damp smell immediately after a cycle is normal. It should be neutral, not foul. Foul means residue somewhere.
Does a garbage disposal cause this?
It can. A dishwasher draining into a disposal that has food sitting in it will pick up the smell, and a disposal plug left in place on a new installation stops the dishwasher draining at all.
Would replacing it be cheaper than fixing it?
For a smell, almost never. For a failed pump or heater on an older machine, sometimes. We will tell you when a repair does not make financial sense rather than quote you for it.
Where to go from here
If the results are the problem rather than the smell, see a dishwasher that is not cleaning properly and film and spots on dishes. For water on the floor, five reasons a dishwasher leaks. The washing machine version of this problem is a washing machine that smells like sewer, and the causes are close to identical.
For anything mechanical, book dishwasher repair in Winnipeg.
Appliance still not right? Our Winnipeg technicians diagnose faults that other companies could not solve. Call (431) 813-3999 or book a visit online. Diagnosis is $85 in the city, and if you go ahead with the repair the quote you are given is the whole price, not a bill on top of the call-out.
