If glasses come out gritty or food particles appear in the bottom of your dishwasher, one of the first things to inspect is the filter. Its job is to catch debris before it can circulate or obstruct the pump. When it becomes clogged, dirty water may drain more slowly and washing results can suffer.
The filter is usually straightforward to clean, but not every dishwasher has the same removable arrangement. Some older models use different filtration systems, and forcing a component that isn't designed to twist out can break it. Start by checking the layout for your particular appliance.
Make sure the dishwasher is safe to handle
Wait until the programme has finished and the interior has cooled. Hot water trapped beneath a filter can scald, and sharp fragments may be hidden in the debris.
Switch the dishwasher off. Follow the manual if it requires disconnecting power before user maintenance.
Remove plates, cutlery and other loose items. Keep children and pets away from the open machine while the lower basket and small filter components are exposed.
Find the filter in the base
On many modern dishwashers, a round filter assembly sits in the floor beneath the lower spray arm. Pull the bottom basket out carefully to see it.
Bosch UK's guide describes unlocking a cylindrical filter at the bottom of its machines, then lifting out the assembly. Other brands may use different clips, handles or arrows.
Don't confuse the filter with the dishwasher's drain pump cover. They may be nearby, but accessing a pump can require a separate process.
Check the manufacturer's removal method
Read the relevant manual or markings around the filter housing. Some cylindrical units turn anticlockwise to unlock; others use a clip or separate coarse screen.
Take a photograph before removing several interlocking parts if that helps with reassembly. Note how the filter sits relative to the spray arm.
If it resists the specified movement, stop and check for a locking mechanism or trapped debris rather than applying more force.
Lift the assembly out carefully
Remove the filter in the direction shown by the maker, letting excess water drip back into the machine.
Inspect for glass fragments, bones or sharp metal before reaching into collected debris. Use gloves where appropriate and do not blindly grab material in a dark sump.
Empty loose food waste into the appropriate bin rather than washing a large amount straight into the kitchen drain.
Separate removable sections
Some filters have an inner fine-mesh cylinder and an outer or flat coarse filter. Bosch explains that its units can be separated for cleaning after removal.
Keep the components together on a clean surface. Check for damaged mesh or cracks while they are out.
Don't prise apart parts that are moulded together or not intended to be separated. The manual determines which pieces are user-serviceable.
Rinse under running water
Hold each suitable filter section under warm running tap water and gently rinse loose grease and food deposits away.
Bosch recommends running water and a small soft brush for debris caught in the filter. Avoid stiff abrasive scourers because they can tear fine mesh.
Work around the edges where small pieces of rice, seeds or labels can lodge. Rotate the filter to inspect both sides rather than cleaning only the visible top.
Clear stubborn greasy residue
If the filter has an oily coating, use a little mild detergent if the manufacturer's cleaning instructions permit it. Rinse it off thoroughly afterwards.
Do not soak plastic components in boiling water unless approved. Sudden high heat can distort some plastic and prevent the filter fitting securely.
Avoid chlorine bleach, strong acids and aggressive drain cleaners. These products may harm seals or components and should not be introduced into a dishwasher casually.
Check the surrounding sump without dismantling it
With the filter removed, you may see debris around the opening. Wipe accessible surfaces gently, taking care of broken glass or other sharp material.
Do not remove a pump impeller cover or reach deep into a drain passage unless the user manual explicitly describes that maintenance.
If you suspect an obstruction beneath the filter, consult the appliance's official blocked-pump troubleshooting guide. A spoon handle pushed into an unknown opening may cause damage.
Reassemble every filter component
Put the cleaned pieces together in their original arrangement and seat the complete assembly in its housing.
Bosch instructs users to twist the assembly until the locking arrows align on suitable models. The exact position may differ on your dishwasher.
A loose or missing filter can allow large debris into the circulation system. Never deliberately run a dishwasher with a filter removed just to 'flush out' the drain.
Make sure the lower spray arm can turn
Once the basket is back in place, ensure the lower spray arm isn't obstructed by the filter or tall items.
If the arm is dirty, follow the manufacturer's separate spray-arm cleaning instructions. Filter cleaning and spray-arm cleaning are related maintenance jobs but are not the same process.
Do not force the arm around a poorly fitted component. Correct installation should leave it able to move as designed.
Run a suitable programme
After everything is locked back into place, run the machine normally or use an approved cleaning cycle if due.
Watch for unusual noises or water escaping. If the dishwasher reports a drain fault, don't repeatedly restart it in the hope the problem will disappear.
If the original symptoms persist, consider the spray arms, drain pump, waste hose and detergent use in the context of the model's troubleshooting guidance.
How often should the filter be cleaned?
Bosch's UK dishwasher maintenance guidance recommends checking or cleaning its filter at least every two weeks for the models covered in its general advice.
Actual frequency depends on how often you use the appliance and how much food residue enters it. A household doing several loads a day may need more frequent inspection.
The best habit is checking before dirt has built up into a thick blockage rather than waiting for the machine to stop draining.
Scrape plates before loading
Large pieces of food, toothpicks, paper labels and fragments of packaging should be removed before plates go inside.
You don't necessarily need to prewash every plate under the tap. Modern dishwashers are designed to deal with ordinary food residue, but not large bones or solid scraps.
Bosch specifically advises scraping food debris to reduce filter, spray-arm and pump blockages. That small action can save considerable cleaning.
Know when it isn't just a dirty filter
Standing water after a completed cycle may indicate a blocked drain hose, pump issue or another fault. A clean filter is worth checking, but it does not prove the plumbing is clear.
If dishes remain greasy while water drains normally, consider loading, detergent, water temperature and spray arms as well.
An unusual burning smell, leaking water or electrical fault is a reason to stop using the machine and arrange service. Filter cleaning is not a fix for every symptom.
Avoid common mistakes
The most damaging mistakes are using an abrasive brush on delicate mesh, breaking a locking clip and forgetting to reseat the assembly.
Another is rinsing away a large clump of food into the sink where it causes another blockage. Put solid debris in the bin first.
Never reach bare-handed into a filter full of unknown sharp pieces. A few seconds of checking is worth avoiding a cut.
A quick routine worth remembering
Cool the machine, remove the lower basket, unlock the user-removable filter, rinse it gently, clear accessible debris and lock it firmly back into place.
Regular checks keep the dishwasher doing its actual job: washing dishes instead of moving yesterday's food particles onto today's glasses.