How to clean a dishwasher step by step

To clean a dishwasher, remove the filters at the bottom and rinse them under running water, clear any blocked nozzles on the spray arms, wipe the door seal and finally run an empty cleaning programme with a special dishwasher cleaner. The filters are worth checking after every wash, and a full clean is advisable roughly once every two months. You can prevent limescale deposits by setting the water hardness correctly and using regenerating salt.

The procedure below is based on the manual for the Bosch SBV6ZCX16E dishwasher and the manufacturer's support pages. The shape of the filters and the position of the parts vary between models, so keep the manual for your own dishwasher at hand.

What you will need

• a soft brush and a cloth,
• a toothpick or tweezers for the nozzles,
• washing-up liquid,
• a sponge and a spoon (in case there is standing water at the bottom),
• a dishwasher cleaner and, if needed, a descaler intended for dishwashers,
• gloves.

1. Filters at the bottom of the dishwasher

The filters catch food residue, and when they become blocked, water cannot circulate and the dishes stay dirty. The Bosch manual recommends checking after every wash whether any food residue has remained in the filters.

1. Remove the lower basket.
2. Turn the coarse filter anticlockwise and pull out the whole filter assembly. Take care that no small objects fall into the pump opening.
3. Separate the assembly: on the model in the manual, the micro-filter is pulled down and the coarse filter is released by pressing the catches.
4. Rinse the parts under running water. Clean thoroughly, especially the edge between the coarse and fine filter, where dirt tends to cling.
5. If heavily soiled, use water with detergent and a soft brush, as recommended by Bosch support on cleaning the dishwasher filter. Do not use abrasive sponges or steel wool.
6. Assemble the filters, insert them back and turn the coarse filter clockwise until the arrow marks line up.

2. Spray arms

According to the manual, limescale and dirt from the wash water can block the nozzles and the mountings of the spray arms, so they should be cleaned regularly. The arms must turn freely and the nozzles must not be blocked.

1. Unscrew the upper spray arm and pull it down.
2. Pull the lower arm upwards.
3. Check under running water that water flows freely from the nozzles. Clear blocked nozzles with a toothpick, as stated on the Bosch page on a dishwasher that does not wash thoroughly.
4. Rinse the arms, let them drain and put them back. Push the lower arm down until it clicks into place and screw the upper one on.
5. Check by hand that both arms turn freely.

3. Door seal, interior and control panel

The manual recommends regularly wiping the door seal, the front of the dishwasher and the control panel with a damp cloth and washing-up liquid. Remove coarse dirt inside the tub with a damp cloth.

Never use products containing chlorine to clean the tub. The Bosch manual explicitly warns that they are a health hazard. A steam cleaner is not suitable either, as according to the manual it may damage the appliance.

4. Cleaning programme

Food residue and limescale gradually build up even in places you cannot reach during routine cleaning. If your dishwasher does not have a cleaning programme reminder, the Bosch manual recommends running it every two months.

1. Clean the filters and remove coarse dirt in the tub.
2. The dishwasher must be empty. Check that there are no aluminium items inside, such as cooker hood grease filters or aluminium pots.
3. Add the cleaner or descaler according to the instructions on its packaging and in the dishwasher manual. On the model in the manual, the descaler goes into the interior and the machine cleaner into the detergent compartment.
4. Start the cleaning programme, or a programme with the highest temperature without any dishes.

Use only products intended for dishwashers. The manual warns that strongly alkaline or strongly acidic cleaning products, especially those from professional establishments, can cause an explosion in combination with aluminium items in the dishwasher. Solvents do not belong in the dishwasher either. How to wash aluminium cooker hood filters safely is described in the article How to clean a cooker hood filter.

Regenerating salt and water hardness

Hard water leaves limescale marks on dishes and in the tub and can clog dishwasher components. That is why most dishwashers have a water softener, which needs special regenerating salt and a correct water hardness setting.

You can find out the water hardness in Prague from the waterworks. Pražské vodovody a kanalizace states that drinking water in Prague is mostly soft to moderately hard, depending on which treatment plant it comes from, and you can find the value for your specific area on their water quality map. For conversion: 1 mmol/l corresponds to 5.6 °dH, which is the unit used by most dishwasher manuals.

• Set the hardness according to the table in the manual. For the Bosch dishwasher in the manual, salt does not need to be used at a hardness of 0 to 6 °dH and the softener can be switched off.
• Use only special dishwasher salt. The manual for this model explicitly excludes table salt and salt tablets.
• Top up the salt just before starting a programme. According to the manual, spilled salt in the tub can cause corrosion.
• According to manufacturers, combination tablets with a salt substitute generally work only up to a hardness of 21 °dH. From 14 °dH, Bosch recommends using salt and rinse aid anyway for the best result.

If limescale also builds up on taps and tiles, the article How to remove limescale will help.

How to load the dishwasher so that it clogs less

Loading it correctly saves a great deal of cleaning work. On its page about a dishwasher that does not wash thoroughly, Bosch recommends:

• putting cups and glasses in the upper basket, pots, pans and plates in the lower one, and heavily soiled dishes at the bottom,
• arranging the dishes so that they do not obstruct the rotation of the spray arms and do not stand in front of the detergent dispenser,
• placing knives and sharp utensils with the point down,
• washing wooden chopping boards by hand,
• choosing a programme with a higher temperature for dishes with dried-on residue.

The washing results will also tell you when cleaning is needed: sand or food residue on the dishes, water at the bottom after the programme ends, white marks on glasses or an undissolved tablet. In that case, first check the filters and arms, and only then look at the programme and detergent.

Why the dishwasher smells and what to do about it

The most common source of odour is food residue in the filters and around the pump, and deposits, which the manual gives as the reason for a regular cleaning programme. The following helps:

• scrape off larger food residue before loading the dishes (according to Bosch, rinsing is not necessary),
• check the filters after every wash,
• wipe the door seal regularly,
• if you are not using the dishwasher for a long time, leave the door slightly ajar, as recommended by the manual.

When there is standing water at the bottom

If the wash water does not drain, the waste water pump is usually blocked. The Bosch manual gives the following procedure: disconnect the dishwasher from the mains, remove the baskets and filters, pump out the water, for example with a sponge, release the pump cover with a spoon and remove food residue and foreign objects. Beware of broken glass and sharp objects that may get caught in the pump. The pump cover must click audibly into place when refitted. If the water still does not drain, it is time to call a service technician.

A washing machine has a similar procedure for the filter and pump, see How to clean a washing machine. Wiping the seal and the front of the dishwasher can also be included in regular home cleaning.