Short answer
Rinse the filter in the base weekly, run a hot cleaning cycle with a machine cleaner once a month, and take the spray arms off to clear the jets every three months.
The intervals at a glance
| Task | Interval | Why |
|---|---|---|
| Rinse the filter | weekly | Otherwise food debris is recirculated back onto the dishes |
| Cleaning cycle at 65–70 °C | monthly | Dissolves the grease film in pump and pipes |
| Wipe the door seal | monthly | Collects grease and hardens until it leaks |
| Remove and rinse spray arms | every 3 months | Blocked jets are the most common cause of poor results |
| Check salt and rinse aid | monthly | Without salt the ion exchanger scales up permanently |
A dishwasher does not clean itself
The objection is reasonable: an appliance running 65 °C water and detergent ought to end up clean. For the inner walls that is true. What remains is everything that drops out of the water circuit: food debris in the filter, grease on the door seal, limescale on the heating element.
Grease is the underrated problem. It is emulsified during the cycle and pushed through pump and pipes, but it settles again as the water cools — in places no detergent reaches. Over months this builds a film that causes smell and reduces pump performance.
The filter is the important weekly job
At the base of the machine sits a multi-part filter: a coarse screen for large debris and a fine micro-filter beneath it. Twist it out, brush it under running water with an old toothbrush, put it back. Two minutes, once a week.
Skip it and something counterintuitive happens: the machine washes the debris back onto your dishes. The water circulates, and whatever the filter fails to hold goes back through the spray arms onto the plates. The typical grey film on supposedly clean dishes comes from exactly this.
The monthly cleaning cycle
Once a month, run the machine empty on its hottest programme with a machine cleaner in the cabinet — not in the detergent compartment, but loose in the lower basket so it acts across the whole cycle. This dissolves the grease film in the pump, hoses and heat exchanger.
Temperature is what matters: grease only dissolves reliably well above 60 °C. An eco cycle at 50 °C washes dishes clean but does not clean the machine. If you run eco exclusively — which makes sense energetically — the monthly hot cycle matters all the more.
Salt, rinse aid, and why all-in-one tabs are not always enough
Dishwashers soften water with an ion exchanger that needs regenerating salt. If the salt reservoir runs dry, the resin scales up — and that damage is not reversible. Dishes go dull and glasses develop a milky haze that no amount of polishing removes.
All-in-one tabs contain a small amount of softener, enough for soft to medium water. Above roughly 14 °dH it is no longer enough and salt needs topping up separately. For that to work, the water hardness must be set correctly in the machine, or it doses the salt wrong.
Common questions
Do I need to pre-rinse the dishes?
No, and it is actively counterproductive. Modern detergents contain enzymes that break down starch and protein — they need something to work on. On pre-rinsed dishes they have nothing to do. Scraping off the coarse debris is entirely sufficient.
Why does my dishwasher smell?
Almost always one of three causes: a full filter, a grease film in the pump and pipes, or a blocked drain hose. Check in that order. If all three are clean and it still smells, the problem is usually in the sink trap it drains into.
Can I put vinegar in the dishwasher?
Better not. Over time the acid attacks rubber seals and the stainless steel fittings. Regenerating salt handles limescale and a machine cleaner handles grease — both are matched to the materials.
How often do the spray arms need cleaning?
Every three months. They usually come off without tools. Clear the jets with a toothpick and flush the arms through — blocked jets are by far the most common reason dishes come out only partly clean.