Dishwasher Not Cleaning Properly - What to Check in St Helens

Published August 2026 | Dishwasher Not Cleaning Properly

This guide walks you through the most common reasons a dishwasher stops cleaning properly and shows you exactly what to check before calling anyone out. Whether your dishes are coming out greasy, gritty, or still covered in food, this is for homeowners who want to diagnose the problem themselves first.

Before You Start - Safety First

Before you touch anything inside your dishwasher, switch it off at the control panel and unplug it from the mains socket. Water and electricity do not mix, and even a machine that appears to be off can still have power running to it through the door switches.

You do not need to turn off your water supply for most of the checks in this guide. If you do need to pull the machine away from the wall - for example to inspect the inlet hose - turn off the isolation valve under the sink first. It is usually a flat-headed screw you turn 90 degrees to close. Our engineers in St Helens see this catch people out regularly, so take a moment to locate yours before you start.

If you smell burning, notice any scorching around the door seal, or see water leaking from underneath the machine, stop. Do not run another cycle. Call a professional instead.

What You Will Need

Most of these checks require nothing more than what is already in your kitchen. Here is what to have ready before you start:

• A soft brush or old toothbrush
• Washing up liquid
• White vinegar (a bottle from any supermarket)
• A bowl or tray to catch water
• A small flathead screwdriver (for some filter covers)
• A torch
• A toothpick or thin piece of wire for clearing spray arm holes

Set aside about 45 minutes to an hour for the full check. If you are dealing with a heavily scaled machine - which is common in parts of Merseyside where water hardness can vary - budget a bit longer for soaking components.

Step-by-Step Instructions

Step 1 - Check and Clean the Filter

The filter is the number one cause of a dishwasher not cleaning properly. It sits at the bottom of the machine, typically beneath the lower spray arm, and catches food debris from every wash cycle. If it is blocked, dirty water recirculates through the machine and deposits itself back onto your dishes.

On most machines - including popular brands like Bosch, Hotpoint, and Beko - the filter comes out by twisting it anticlockwise and lifting it free. Some models have a two-part filter: a coarse mesh outer section and a finer cylindrical inner piece. Remove both. Check your instruction manual for the specific procedure on your model, as filter designs vary.

Rinse the filter under warm running water and use an old toothbrush to scrub away any grease or food residue. For stubborn buildup, soak it in warm soapy water for 10 to 15 minutes before scrubbing. You should be able to hold it up to the light and see through the mesh clearly before you put it back.

Our engineers in St Helens find that a blocked or dirty filter is responsible for the majority of poor cleaning complaints. In most cases, cleaning the filter alone resolves the problem entirely.

Step 2 - Inspect and Clear the Spray Arms

Your dishwasher has at least two spray arms - one beneath the lower rack and one beneath the upper rack. Some machines, including certain Samsung and LG models, have a third arm at the very top of the cabinet. These arms spin during the wash and jet water over your dishes. If the holes are blocked, coverage drops dramatically and whole sections of the wash get almost no water at all.

Remove each spray arm - they typically unscrew or unclip by pulling upward - and hold them up to the light. Look through each individual hole. Food debris, limescale, and even small fragments of broken glass can block them. Use a toothpick or thin wire to clear each hole one by one.

Once cleaned, put the arms back and give each one a spin by hand. It should rotate freely without any resistance. If it catches on something, check that no tall items in the rack are hanging down and obstructing the arm during the cycle.

Step 3 - Check the Detergent Dispenser

A dispenser that is not releasing the tablet or powder at the right point in the cycle will leave your dishes dirty regardless of everything else working correctly. Open the dispenser door manually and look for any detergent residue inside. If old detergent has caked up around the lid or the hinge mechanism, it may not be opening fully during the wash.

Clean the dispenser compartment with a damp cloth and make sure the lid clicks shut properly before running a cycle. If you use tablets, check that the tablet is sitting flat inside the compartment and not jammed sideways. After a cycle, if you find an undissolved tablet or an intact tablet wrapper still sitting in the dispenser, you have found your problem.

Also check you are using the correct amount of detergent for your water hardness. In parts of Merseyside, water hardness varies enough to affect how well detergent performs. If you use powder or gel rather than tablets, you may need to increase the dosage slightly if your water is on the harder side.

Step 4 - Check Salt and Rinse Aid Levels

UK dishwashers use salt to regenerate the internal water softener, which both protects the machine from limescale damage and improves cleaning results. If the salt reservoir is empty, you will typically see a warning light on the control panel - but not always. Some older Hotpoint and Beko machines are less obvious about flagging it.

The salt reservoir is at the bottom of the dishwasher tub, sealed with a screw cap. Open it and look inside. You should see white granules. If it looks empty or there is water sitting there with no salt visible, refill it with dishwasher-specific salt only - never table salt or cooking salt, as these can damage the softener unit.

Rinse aid goes into a separate reservoir near the detergent dispenser. If it is low or empty, dishes will come out streaky and still wet. Top it up and run a cycle to see if that makes a difference.

Step 5 - Review How You Are Loading the Machine

Loading errors are one of the most frequently overlooked causes of poor cleaning results, and one of the most common things our engineers come across in St Helens when investigating a complaint. Overcrowding the racks means water cannot reach all surfaces. Large items blocking the spray arms mean entire sections of the wash get no coverage at all.

Follow these loading basics for better results:

• Face plates and bowls inward toward the centre of the rack
• Do not nest spoons and forks together - alternate them in the cutlery basket
• Put tall items like baking trays and chopping boards around the outside edges of the lower rack
• Make sure nothing is hanging down through the lower rack and blocking the spray arm below it
• Glasses and cups go upside down in the upper rack so water drains off them

Run a test cycle with a lighter load than usual and compare the results. If cleaning improves noticeably, overloading was the issue.

Step 6 - Run a Dedicated Cleaning Cycle

If the machine has not had a cleaning cycle in a while, grease and mineral deposits can build up inside the drum, on the door seal, and in the internal pipework. This affects how effectively the machine cleans everything that goes inside it.

Pour 250ml of white vinegar into a dishwasher-safe bowl and place it on the bottom rack. Run the hottest programme available with nothing else in the machine. Vinegar helps dissolve limescale and grease from internal surfaces. After that cycle, sprinkle a handful of bicarbonate of soda across the bottom of the drum and run a short hot cycle.

You can also use dedicated dishwasher cleaner products - brands like Finish produce specific cleaning tablets designed for this. We typically recommend running a cleaning cycle like this every one to three months as routine maintenance to keep the machine performing well.

Step 7 - Check the Water Temperature

Dishwashers need hot water to dissolve grease and activate detergent properly. Most machines heat their own water internally, but if the heating element is starting to fail, water may not reach the required temperature. The typical operating temperature for a main wash cycle is between 50 and 65 degrees Celsius.

You can check this roughly by running a cycle and placing your hand flat on the exterior of the door about 20 minutes in - it should feel clearly warm to the touch. If the machine feels cold during the cycle and your dishes are consistently greasy rather than just gritty, a failing heating element could be the cause. That is not a DIY repair - it needs a trained engineer with the right equipment to test and replace safely.

What to Do If This Does Not Fix It

If you have worked through all seven steps and your dishwasher is still not cleaning properly, the issue is likely internal and will need further diagnosis. Common underlying causes at this stage include a faulty circulation pump - responsible for pushing water through the spray arms - a blocked or failed inlet valve, or a worn wash motor.

Before booking an engineer, try using the Voltrade GoFIX diagnostic tool. It asks you a series of questions about what your machine is doing and which symptoms you are seeing, then gives you a shortlist of likely causes along with an estimated repair cost. This means you go into any conversation with a repairer knowing exactly what you are dealing with, rather than taking someone's word for it.

You can also try running the machine on its hottest setting with a commercial dishwasher cleaner as a final attempt. In some cases, a heavy-duty clean cycle will shift buildup in internal components that a standard rinse cycle misses.

When to Stop and Call a Professional

Some dishwasher problems are outside the scope of what a homeowner should attempt. Call a qualified appliance engineer if:

• You can hear the motor running but no water is entering the machine - this points to a blocked or failed inlet valve
• The machine fills with water but you cannot hear the spray arms running - likely a circulation pump fault
• Water is pooling in the bottom of the tub after the cycle finishes - could be a drain pump failure
• You see any signs of burning or smell an electrical burning odour from the machine
• Your control panel is showing error codes that will not clear after a reset

For most repair jobs in St Helens and across Merseyside, a call-out and labour charge typically runs between 60 and 100 pounds. Parts vary considerably by brand and model - a replacement circulation pump for a Bosch or Samsung machine typically costs between 40 and 120 pounds for the part alone. A full heating element replacement including parts and labour usually comes out somewhere between 100 and 200 pounds.

If the total repair cost is approaching 60 to 70 percent of what the machine would cost to replace new, it is worth having a frank conversation with the engineer about whether repair or replacement makes more financial sense. A good engineer will give you an honest assessment. When booking in Merseyside, check that the engineer has experience with your specific brand - Bosch and Siemens machines in particular use proprietary parts that require some brand familiarity to diagnose correctly.

Questions About This Process

How often should I clean my dishwasher filter in St Helens?

Most manufacturers recommend checking and cleaning the filter at least once a month. If you are running the machine daily or cooking meals that produce a lot of food debris - rice, pasta, lentils - check it every two to three weeks. Keeping on top of it is much easier than clearing a heavily clogged filter that has been left for months, and it makes a noticeable difference to cleaning results over time.

Why are my dishes coming out with white spots or a cloudy film?

White spots and a cloudy film on glasses are typically caused by limescale deposits or insufficient rinse aid. Check your rinse aid reservoir first and top it up if it is low. Also confirm your dishwasher salt is full, since the internal softener depends on it to treat incoming water. If the problem persists, try increasing the rinse aid dosage setting on your machine - this is usually adjustable through the settings menu on most Bosch, Hotpoint, and Beko models.

Is it worth repairing my dishwasher or should I buy a new one?

As a rough guide, if the machine is less than five years old and the repair cost is under half the price of a replacement, repair is usually the sensible option. For machines over eight to ten years old, factor in that other components are also ageing and may fail soon after a repair. In St Helens and across Merseyside, a decent mid-range replacement dishwasher typically costs between 350 and 600 pounds supplied and installed, so weigh the repair quote against that figure when making your decision.