When your dishwasher begins to smell, leaves grit on glasses or simply stops cleaning as well as it once did, it probably needs some attention. Fortunately, cleaning a dishwasher rarely requires dismantling the machine or experimenting with a cocktail of household chemicals.
The quick answer: Empty the dishwasher, remove debris, wash the removable filter, inspect the spray arms, wipe the door seals and run an empty cleaning cycle using a product approved by the manufacturer. For a frequently used dishwasher, aim to do this roughly once a month.
This guide explains how to clean a dishwasher safely, including what to do about standing water, mineral deposits and stubborn odours.
How often should you clean a dishwasher?
There is no single schedule for every household. A dishwasher used twice a day will need attention sooner than one used twice a week. Hard water, greasy cookware and the amount of food left on dishes can also affect how quickly residue accumulates.
| When | What to do |
|---|---|
| After each load | Remove any large pieces of food left in the bottom of the machine. |
| Weekly | Check the filter area, wipe visibly dirty door edges and make sure the spray arms can rotate freely. |
| Monthly | Clean the filter and give a frequently used dishwasher a more thorough inspection. |
| Every 3 to 6 months | Use a manufacturer-approved cleaner or descaler if needed, particularly in a hard-water area. |
| As soon as a problem appears | Investigate persistent smells, poor drainage, gritty dishes, leaks or a noticeable decline in cleaning performance. |
This is a practical schedule rather than a rigid rule. Your dishwasher manual may recommend different intervals for your particular model.
How to clean a dishwasher step by step
1. Empty the dishwasher and check the manual
Remove all dishes, racks of loose items and cutlery. Switch the dishwasher off before removing any user-serviceable parts.
Then consult the manual, especially if this is the first time you have cleaned the filter or spray arms. Filters, fasteners and cleaning programmes differ between manufacturers. If the paper manual has vanished, search for the model number on the manufacturer’s website.
Avoid removing pumps, electrical components or fixed panels unless the manual specifically identifies them as user-serviceable. Those jobs belong to a qualified technician.
2. Remove food and debris from the tub
Inspect the bottom of the dishwasher for food scraps, pieces of glass, labels from jars and other debris. Wear gloves if broken glass may be present, and remove sharp objects carefully.
Pay particular attention to the area around the filter and drain opening. Debris here can create odours and interfere with drainage.
A small amount of water beneath the filter or inside the sump can be normal because it helps prevent seals from drying out. A visible pool covering the floor of the dishwasher is different and may indicate a blocked filter, obstructed drain hose or drainage fault.
3. Clean the dishwasher filter
The filter is usually found beneath the lower spray arm, although its precise position and removal method depend on the model.
- Remove the lower rack.
- Unlock and lift out the filter according to the manual.
- Rinse it under warm running water.
- Use a soft brush and a little mild washing-up liquid to loosen greasy residue.
- Rinse thoroughly and reinstall it securely.
Do not use a wire brush or abrasive scouring pad, as these can damage the filter mesh. It is also important to lock the filter back into position. A loose or incorrectly installed filter may allow debris to reach parts of the machine it should not.
For a dishwasher used regularly, Bosch recommends checking and cleaning the filter approximately once a month. Other manufacturers may specify a different schedule.
4. Inspect and clean the spray arms
The spray arms distribute water around the dishwasher. If their holes become obstructed by food, mineral deposits or fragments of packaging, some dishes may receive very little water.
First, turn each arm by hand to make sure it can rotate freely. Check that tall plates, utensils or pan handles will not obstruct it once the dishwasher is loaded.
If your manual permits the arms to be removed, rinse them with warm water and gently clear blocked holes using a wooden toothpick or another non-metallic tool. Do not enlarge the holes or force anything deep inside them.
Bosch provides model-specific instructions for cleaning removable spray arms, but you should follow the directions for your own appliance.
5. Wipe the door, seals and detergent compartment
The main washing cycle does not always reach the outer edges of the door. Grease, crumbs and mould can therefore collect around the gasket, hinges and lower lip.
Use a soft damp cloth with a small amount of mild detergent to wipe:
- the rubber door gasket;
- the sides and lower edge of the door;
- the detergent and rinse-aid compartments;
- the area around the hinges; and
- the controls, using only a lightly dampened cloth.
Do not flood the gasket or control panel with water. Check the seal for cracks, deformation or areas that have pulled away from the door. A damaged gasket may need replacing if the dishwasher is leaking.
6. Deal with grease, limescale and mineral deposits
White film or chalky deposits usually point to hard water rather than ordinary food residue. Greasy buildup, meanwhile, can result from repeatedly using short or low-temperature programmes for heavily soiled loads.
The safest option is a dishwasher cleaner or descaler specifically approved for your model. Follow both the appliance manual and the cleaner’s instructions, including the recommended cycle and dosage.
Vinegar is frequently promoted as a universal dishwasher cleaner, but it is acidic and repeated exposure may harm certain seals, hoses or metal components. Only use it if your dishwasher manufacturer permits it. If allowed, place it in a dishwasher-safe container on a rack rather than pouring it directly into the machine.
Never combine vinegar, descaler, bleach or another cleaning product. In particular, the CDC warns that bleach must not be mixed with other cleaners because dangerous vapours can be released.
7. Run an empty cleaning cycle
Replace the filter and spray arms, then run the dishwasher empty using its machine-care programme, if it has one. Otherwise, use the cycle recommended by the manufacturer or the instructions on an approved dishwasher cleaner.
Do not use ordinary hand-washing liquid. It produces far more foam than dishwasher detergent and can cause suds to escape from the machine.
There is also no need to pour boiling water into the dishwasher. The appliance controls its own water temperature, while sudden exposure to boiling water could damage plastic components or seals.
8. Wipe the interior and let it dry
Once the cycle finishes and the interior has cooled, wipe away any remaining residue with a clean cloth. Leave the door slightly open for a while so moisture can escape.
If the dishwasher still smells immediately after a thorough clean, the problem may be deeper in the drainage system rather than on the visible surfaces.
Why does my dishwasher smell?
A smelly dishwasher is usually caused by trapped food, greasy residue or water that is not draining properly. Common culprits include:
- a dirty filter;
- food trapped beneath the filter or around the door seal;
- a blocked spray arm;
- an obstructed or incorrectly installed drain hose;
- standing water caused by a drainage fault; or
- long periods with the door closed while the interior is damp.
Begin with the filter, tub and gasket. If the odour resembles sewage, returns quickly or is accompanied by widespread standing water, inspect the drainage guidance in the manual or contact a technician.
Why is there water in the bottom of my dishwasher?
A shallow amount of water inside the sump, below the filter, may be part of the dishwasher’s normal design. Water spread across the tub floor after a completed cycle is more likely to signal a problem.
Check that:
- the filter is clean and correctly installed;
- the programme finished rather than being interrupted;
- the kitchen sink and shared waste connection are draining;
- the accessible portion of the drain hose is not kinked; and
- the waste-disposal connection, if present, is correctly configured.
Do not reach into a pump or remove fixed covers while the appliance is connected to power. If the water remains after the accessible checks, arrange a repair rather than repeatedly running the machine.
Why are dishes still dirty after a cycle?
A dirty dishwasher is only one possible explanation. Poor results can also come from loading, detergent or programme selection.
- Grit or food particles: Clean and securely reinstall the filter.
- Dirty items in one part of the rack: Inspect the corresponding spray arm for blocked holes.
- Food remains on crowded dishes: Leave space for water to circulate and avoid overlapping plates.
- Cloudy glasses or white deposits: Check for hard water, rinse-aid settings and limescale.
- Greasy cookware: Choose a programme designed for heavily soiled loads.
- Detergent left in the dispenser: Make sure a large plate or utensil is not blocking the compartment.
Items should generally face the centre and downward towards the spray, while the arms must be able to rotate freely. Bosch offers a useful visual guide to dishwasher loading, although rack layouts differ between brands.
How dishwasher maintenance saves water and energy
A properly loaded, well-maintained dishwasher can be an efficient way to wash dishes. Blocked spray arms, a clogged filter or an unsuitable programme may lead to poor results and repeat cycles, wasting both water and electricity.
For more efficient washing:
- scrape plates rather than thoroughly pre-rinsing them under running water;
- wait for a full load, but do not overcrowd the racks;
- use the eco programme when it is suitable for the load;
- select air drying or open-door drying if your model provides it;
- keep the filter and spray arms clear; and
- repair serviceable faults instead of replacing the entire appliance prematurely.
Eco programmes often take longer because they reduce energy use by heating water more gradually and relying on longer soaking periods. A longer cycle does not necessarily mean a more wasteful one.
ENERGY STAR reports that efficient modern dishwashers can use substantially less energy than washing dishes by hand, although the comparison depends on the appliance, programme and hand-washing method.
The dishwasher is only one part of household consumption. Our discussion of energy-efficient homes and climate change considers why efficient technology works best alongside thoughtful everyday behaviour. Similar questions arise around the environmental impacts of laundry and the choices covered in our eco laundry guide.
When should you call a dishwasher technician?
Stop using the dishwasher and seek professional help if you notice:
- a burning smell, smoke or signs of overheating;
- water leaking from beneath the appliance;
- repeated electrical faults or tripped circuits;
- standing water that remains after the filter and accessible drain areas are checked;
- a damaged power cable, hose or door seal;
- unusual grinding noises; or
- an error code that returns after following the manual.
If the machine is leaking or appears electrically unsafe, switch off its power and water supply if you can do so safely. Do not continue running test cycles.
Frequently asked questions
Can I clean a dishwasher with vinegar?
Only if the manufacturer of your dishwasher permits it. Vinegar is acidic and may damage some seals, hoses and metal components. A manufacturer-approved dishwasher cleaner is the safer default. Never mix vinegar with bleach or another cleaning product.
Can I use bleach in a dishwasher?
Do not use bleach unless your appliance manual explicitly says it is safe. Bleach can damage stainless steel and must never be combined with vinegar, ammonia, descaler or another cleaner.
Can I use baking soda to clean a dishwasher?
Baking soda may be suitable for some dishwasher interiors, but it should not be treated as universally safe. Check the appliance manual first and never combine it with another cleaner inside the machine.
How often should I clean the dishwasher filter?
For a frequently used machine, monthly is a sensible starting point. Clean it sooner if you notice odours, visible debris, gritty dishes or slower drainage. The manufacturer may recommend a different interval based on the filter design.
Should I rinse plates before putting them in the dishwasher?
Remove bones, seeds and large food scraps, but thorough rinsing is usually unnecessary for a modern dishwasher. Excessive pre-rinsing wastes water. Follow the appliance and detergent manufacturer’s directions if your results are inconsistent.
Is a little water beneath the dishwasher filter normal?
Often, yes. Some machines retain a small amount of water in the sump. Water covering the tub floor, producing persistent odours or remaining with food debris is more likely to indicate a drainage problem.
Why does my dishwasher smell even after cleaning?
The drain hose, waste connection or pump may contain trapped material, or the dishwasher may not be draining completely. If the filter, seals and accessible tub are clean but the smell quickly returns, consult the manual or arrange an inspection.
Does a dishwasher need a hot empty cycle?
An occasional empty machine-care cycle can help remove grease and residue. Use the programme and cleaning product recommended for your model rather than automatically choosing the hottest possible setting.
A clean dishwasher should not require guesswork
The most useful dishwasher maintenance is also the least dramatic: remove debris, clean the filter, keep the spray arms unobstructed and use the correct programme. These small actions can improve cleaning performance, prevent unnecessary repeat cycles and help the appliance remain useful for longer.
When a problem persists after these basic checks, resist the temptation to dismantle the machine or add stronger chemicals. The manual, the manufacturer and a qualified repairer are safer guides than an improvised cleaning mixture.