A dishwasher that smells is not failing to wash; it is failing to drain and dry. Food particles, rinse aid residue and hard-water scale collect in the filter, the spray arms and the door seal, and those three places decide whether the machine smells clean or sour.
Clean the filter first, always
Start by removing and washing the filter, because that is where the smell and the performance loss begin. Then run a hot cycle with a descaler or a machine cleaner, wipe the door seal and the detergent dispenser by hand, and check the spray-arm holes for blockages.
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The five-minute filter job
- Pull the bottom rack out and lift out the filter assembly (most machines have a coarse and a fine filter).
- Rinse both under warm running water and scrub with a soft brush. If the mesh is greasy, use a little machine dishwash liquid rather than an abrasive pad.
- Check the sump below the filter for glass and food debris and wipe it out.
- Refit, and make sure the filter seats flat. A filter that sits proud lets food recirculate, which is why dishes come out gritty.
The maintenance cycle
Run the machine empty on the hottest cycle with a descaler at label dilution. That removes the mineral film from the heating element and the pump, which is the film that makes glasses look cloudy and the machine smell after a cycle. Where the water is hard, do this monthly rather than yearly.
| Product | Use | Price |
|---|---|---|
| Machine Dishwash Liquid 128 | Everyday machine detergent | A$32.00 |
| Machine Dishwash Powder 510 | Heavier soil and baked-on starch | A$48.00 |
| Freshway Descaler 145 | Scale removal in the maintenance cycle | A$48.00 |
| Freshway Rinse Aid 140 | Drying and spotting control | A$35.00 |
| Rinse Aid with built-in descaler | Rinse aid with descaling action | A$43.00 |
Spray arms, seals and the dispenser
The spray arms lift out on most machines. Hold them up to the light and clear any blocked holes with a pin or a piece of fine wire; scale and food lodge in the end jets first, which is why the back of the load comes out dirty.
Then the door seal: run a cloth around the inner fold and the corners. That black film is biofilm, and it is the source of the smell that returns the day after a clean. Finish with the detergent dispenser and the rinse-aid reservoir, which both hold residue that goes stale.
Vinegar, bicarb and the dishwasher tablet trick
Vinegar is a weak acid, so it softens light scale and does not touch grease or biofilm. A dishwasher tablet in an empty machine is a common suggestion and it does clean mildly, because tablets contain alkalinity and enzymes — but the dose is designed for a full load, and the tablet never reaches the filter, which is where the problem usually is.
Bicarbonate of soda is a mild abrasive and a deodoriser. It is useful on the seal and the door, and it does nothing for scale on the element. Match the chemistry to the problem: acid for scale, alkaline for grease, and elbow grease for the filter.
Commercial machines and food premises
A commercial dish or glasswasher needs the same three jobs on a documented schedule: filter and sump daily, seals and spray arms weekly, descale monthly or to the water hardness. Food Standards Australia New Zealand sets the sanitation expectations for food premises, and SafeWork NSW covers the chemical handling in chemicals and other substances.
Questions we get asked most
- What is the best thing to clean the inside of a dishwasher?
- A descaler on an empty hot cycle for scale, and a machine detergent for grease, plus hand cleaning of the filter, seal and dispenser. The hand work is what removes the biofilm that causes the smell.
- How do I deep clean my dishwasher?
- Remove and scrub the filter and sump, clear the spray-arm holes, wipe the door seal fold and the dispenser, then run the hottest cycle with a descaler. Repeat the cycle on badly scaled machines.
- Can you run vinegar through a dishwasher to clean it?
- You can, and it works on light scale because it is acidic. It does nothing for grease or biofilm, and on hard water it is much weaker than a formulated descaler.
- Do you just run an empty dishwasher to clean it?
- No. An empty cycle with a cleaner treats the inside of the tank, but the filter, seal and spray arms need the machine open and a cloth or brush. Those are the parts that make it smell.
- How often should a dishwasher be cleaned?
- Filter weekly in a domestic machine and daily in a commercial one; a descale cycle monthly in hard water. In a food business, put all three on the cleaning schedule and record them.
References
- Food Standards Australia New Zealand — cleaning and sanitation in food premises.
- SafeWork NSW — chemicals and other substances.
Running a commercial dish or glasswasher?
Tell us the machine and how hard the water is, and we will set up the detergent, rinse aid and descaling schedule around it. Browse cleaning chemicals or ask our team.