Quick answer: Remove and clean the filter under a tap weekly, unclip the spray arms and clear their nozzles with a cocktail stick, then run an empty hot cycle with a cup of white vinegar in the bottom, followed by a second hot cycle with bicarbonate of soda. Wipe the door seal with a damp cloth after each use to stop mould building up in the folds.
A dishwasher is supposed to clean itself as a side effect of cleaning your dishes, but that is only true up to a point. Grease, food debris, and limescale build up in places the daily cycle does not fully reach, which is why dishes can start coming out less than sparkling even though nothing else has changed.
Why Dishwashers Need Cleaning
Food particles, grease, and detergent residue collect in the filter and spray arm nozzles over time, gradually reducing how effectively water circulates during a wash. In UK homes with hard water, limescale adds to this build-up, coating internal surfaces and, on newer machines, sometimes interfering with sensors. Left unchecked, the result is smells, cloudy glassware, and dishes that need rewashing.
What You Will Need
- White vinegar
- Bicarbonate of soda
- An old toothbrush or small brush
- A cocktail stick
- A microfibre cloth
Step 1: Clean the Filter
The filter sits at the base of the dishwasher, usually under the bottom basket, and catches food particles and debris before they can recirculate onto your dishes.
- Remove the filter, which typically twists or lifts out by hand.
- Rinse it under a running tap to clear loose debris.
- Scrub any trapped residue with an old toothbrush, paying attention to the mesh and any small gaps.
- Reinsert the filter, making sure it clicks or twists back into place securely.
Clean the filter weekly, or more often if you notice food debris building up quickly.
Step 2: Clean the Spray Arms
The spray arms distribute water during the wash, and their small nozzles are prone to blocking with food particles and limescale.
- Unscrew the upper spray arm and unclip the lower one, following your model’s release mechanism.
- Use a cocktail stick to clear out each nozzle individually, checking that water can pass freely through.
- For heavier blockages, soak the spray arms in a vinegar solution to dissolve limescale and food residue.
- Rinse thoroughly under a tap, then reattach both arms and give them a manual spin to confirm they move freely.
Step 3: Clean the Door Seal
The rubber seal around the door traps moisture and food splashes, making it a common source of smells and mould if left unattended.
- Wipe around the entire seal with a damp cloth, paying attention to the folds where residue collects.
- For visible mould or grime, use a cloth dampened with white vinegar and leave it against the seal for a few minutes before wiping.
- Dry the seal afterwards to reduce the chance of mould returning.
Step 4: Deep Clean the Interior
- Empty the dishwasher completely so nothing is left inside during the clean.
- Place a cup of white vinegar upright in the top rack, or pour it into the base of the machine.
- Run a full hot cycle, ideally at 60°C or higher.
- Once finished, sprinkle a cup of bicarbonate of soda across the base and run a second, shorter hot cycle to lift any remaining odours and residue.
Use cleaning vinegar or distilled white vinegar rather than other types, since some vinegars contain plant dyes that can discolour certain surfaces inside the machine.
Step 5: Clean the Exterior
Wipe down the control panel, door, and handle with a soft cloth and a mild cleaning spray. Avoid abrasive cleaners on the display panel, since these can scratch or dull the finish over time.
Descaling in Hard Water Areas
If you live in a hard water area, limescale can build up faster than a standard vinegar clean fully addresses, particularly around the heating element and internal sensors on newer smart dishwashers. A dedicated dishwasher descaler or cleaner formulated with citric acid, run through an empty hot cycle, tackles this more thoroughly than vinegar alone and is worth using every few months in these areas.
How Often Should You Clean a Dishwasher?
- Filter: weekly, or whenever visibly clogged
- Spray arms: monthly, or sooner if you notice uneven cleaning
- Door seal: wipe after each use, deep clean monthly
- Full interior deep clean: every three to six months for most homes, quarterly in hard water areas or with daily use
Preventing Build-Up Between Cleans
- Scrape large food scraps into the bin before loading dishes, rather than relying on the filter to catch everything.
- Run a hot wash regularly rather than only ever using cooler eco cycles, since higher temperatures help prevent grease build-up.
- Leave the door slightly ajar after a cycle finishes to let the interior air out and dry properly.
Related Guides
Frequently Asked Questions
Why does my dishwasher smell?
Trapped food debris in the filter, blocked spray arm nozzles, and moisture in the door seal are the most common causes. A regular clean of all three usually resolves persistent smells.
How often should I clean my dishwasher filter?
Weekly for most households, or more often if you notice food debris building up or dishes coming out less clean than usual.
Can I use vinegar and baking soda in the same dishwasher cycle?
It is better to run them in separate cycles rather than combining them, since mixing the two reduces their individual cleaning effectiveness.
Does hard water affect dishwasher performance?
Yes. Limescale from hard water builds up on internal surfaces and heating elements, reducing efficiency over time and, on some newer models, potentially interfering with sensors.
Final Thoughts
A dishwasher stays effective when the filter, spray arms, and door seal are kept clear of the build-up they naturally collect during normal use. A weekly filter check, a monthly deep clean, and extra attention to descaling in hard water areas will keep both the machine and your dishes properly clean.