Dishwasher Not Cleaning Properly - What to Check in Andover

Published September 2026 | Dishwasher Not Cleaning Properly

You unload the dishwasher after a full cycle and the glasses are cloudy, the plates still have last night's pasta baked onto them, and the mugs smell vaguely of old water. It's one of those annoying domestic problems that sneaks up on you - the machine is running, it's filling with water, it sounds normal, but the results are getting worse week by week. For a lot of Andover homeowners, the instinct is to assume the machine is dying, but in most cases the fix is simpler than you'd expect.

Understanding What's Actually Going Wrong

A dishwasher cleans through a combination of hot water, detergent, and mechanical spray action. When any one of those three elements is compromised, the results deteriorate. The machine may complete its programme and drain correctly, which is why it can be confusing - nothing obviously breaks, the cycle runs, but the dishes come out dirty.

What our engineers see most often is a gradual decline rather than a sudden failure. A filter that hasn't been cleaned in six months, spray arm holes that have silently blocked with mineral deposits, or a detergent dispenser that's sticking shut. These issues compound each other. Hard water - which is common across Hampshire - accelerates limescale build-up on the internal components, and that limescale then reduces water pressure through the spray arms, which reduces cleaning effectiveness, which means food residue builds up faster on the filter. It becomes a cycle.

Before assuming you need a new appliance or even an expensive repair, it's worth working through the most likely causes methodically. The Voltrade GoFIX diagnostic tool can help you identify the exact fault before any engineer visits, which saves time and means you're not paying for unnecessary call-outs.

The Most Common Causes of Poor Dishwasher Cleaning

A Blocked or Dirty Filter

The filter is the single most common cause of dishwashers underperforming. It sits at the bottom of the machine, usually under the lower spray arm, and its job is to catch food particles and debris so they don't recirculate onto your dishes. When it blocks up, water flow is restricted and dirty water can actually be redistributed around the drum during the wash cycle.

Most manufacturers recommend cleaning the filter every month, but realistically most people do it far less often. On a Bosch or Siemens machine, you'll find a cylindrical filter that twists out by hand. On Hotpoint and Indesit models, the filter system is slightly different but equally accessible. Rinse it under warm running water and use an old toothbrush to clear any stubborn debris from the mesh. If it's heavily caked, a short soak in white vinegar will break down grease and limescale.

Blocked Spray Arms

The spray arms - typically one below the lower rack and one under the upper rack - rotate and jet water across your dishes. The small holes along these arms can become blocked with limescale deposits, food particles, or even tiny bits of broken glass or labels from jars. When the holes block, the water pressure drops and coverage becomes uneven, which explains why you might notice the top rack isn't getting cleaned while the bottom rack is fine.

Remove the spray arms (most simply unclip or unscrew) and hold them up to the light. You should be able to see through each hole clearly. Use a cocktail stick or thin wire to clear any blockages, then run water through them to flush everything out. On machines like the Samsung DW60M series or LG QuadWash models, the spray arm design varies, so check your manual if the arms don't come away easily.

The Detergent Dispenser Isn't Opening Properly

If your detergent tablet or powder isn't dissolving, the chemistry side of the wash is basically missing. The dispenser door is spring-loaded and opens at a specific point in the wash programme. If the door is obstructed by a large item in the lower rack, or if the spring mechanism has become stiff or faulty, the tablet can sit in the dispenser through the entire cycle and come out intact at the end.

Check that nothing in the lower rack is physically blocking the dispenser door. It's also worth testing whether the door springs open freely when you press the release by hand. If it feels stiff or sluggish, the spring or latch mechanism may need replacing - that's a relatively minor repair, typically costing between 40 and 80 pounds for parts and labour.

Water Temperature Is Too Low

Dishwashers clean most effectively at 60 to 65 degrees Celsius on a standard programme. If the water isn't getting hot enough, detergent won't activate fully and grease won't break down. The heating element inside the machine warms the water during the cycle, but if it's failing or the thermostat is faulty, temperatures may be significantly below what the programme specifies.

A quick test: open the door partway through a hot wash and feel the steam. If there's very little heat coming out compared to usual, low water temperature is likely the issue. A faulty heating element on a Beko or Hotpoint dishwasher typically costs between 80 and 150 pounds to replace including labour, making it worth repairing on a machine that's otherwise in good condition.

Limescale Build-Up from Hard Water

Hampshire has moderately hard water across much of the county, and in some parts of Andover the hardness level is high enough to cause noticeable build-up on glassware and internal components within months. Limescale coats the heating element (reducing its efficiency), furs up the spray arm holes, and leaves that characteristic white film on glasses and cutlery.

If you're not already using a rinse aid, start. It makes a significant difference to drying and prevents mineral deposits on glassware. Check that your dishwasher's salt reservoir is topped up - dishwasher salt softens the water entering the machine and dramatically reduces limescale build-up. The salt compartment is usually at the bottom of the drum. Running a dedicated dishwasher cleaner or a cup of white vinegar on an empty hot cycle every month or two keeps the internal components clear.

Overloading and Incorrect Loading

This sounds obvious, but it's remarkably easy to pack a dishwasher in a way that physically blocks water from reaching everything. Bowls nested inside each other, plates too close together, mugs loaded face-up so they fill with water rather than drain - all of these reduce cleaning effectiveness regardless of how well the machine itself is performing.

As a general rule: place plates facing the centre, bowls and cups on the upper rack angled downwards, and keep large items from blocking the rotation path of the spray arms. Pots and pans should go on the lower rack with their soiled surfaces facing the spray. On the upper rack, glasses should have enough gap between them that water can get to all surfaces.

Solutions That Actually Work

Work through these steps before calling anyone out. In our experience, this sequence resolves the problem in the majority of cases:

1. Remove and clean the filter thoroughly. If you can't remember the last time you did it, assume it needs doing.
2. Remove both spray arms and clear every hole with a cocktail stick. Run water through them to confirm they're clear before refitting.
3. Check the salt reservoir and top up if needed. Check the rinse aid dispenser too.
4. Ensure the detergent dispenser opens freely and isn't being blocked by items in the lower rack.
5. Run an empty hot cycle with a dishwasher cleaning tablet or 200ml of white vinegar placed in the bottom of the drum. This addresses internal limescale and grease.
6. Check your loading pattern against the diagrams in your machine's manual.
7. Run a full cycle on the hottest programme with a single tablet and note the results.

If the machine cleans well after this, you've likely solved it with maintenance rather than repair. Run a maintenance clean every four to six weeks to keep it performing consistently.

When to Call a Professional vs Sort It Yourself

The issues above are all things a homeowner can reasonably tackle without tools or technical knowledge. If you've worked through all of them and the machine still isn't cleaning properly, the problem is likely a component failure that needs a professional diagnosis.

Call an engineer if:

• The machine isn't reaching temperature - this suggests a faulty heating element or thermostat
• You can hear the pump running but water isn't reaching the spray arms - could indicate a circulation pump fault
• The detergent dispenser opens but the tablet doesn't dissolve even on a hot cycle - may point to low water flow or a wash arm sealing issue
• There's standing water in the bottom after a cycle - drainage pump or filter housing fault
• The machine is showing an error code - consult the manual first, but codes like E15 on Bosch machines or F01 on Hotpoint indicate specific component failures

Repair costs for most component failures in Andover typically range from 80 to 220 pounds depending on the part and the machine. A new budget dishwasher starts at around 250 to 300 pounds, so repair is almost always worth it on a machine that's fewer than seven or eight years old and otherwise functioning well.

What to Expect from a Repair Visit

When an appliance repair engineer visits your home in Andover, the visit typically follows a clear process. The first appointment is a diagnostic visit - the engineer will run through the fault symptoms with you, test the machine's key systems, and identify the cause. This usually takes 30 to 45 minutes and costs between 60 and 90 pounds, which is commonly waived if you proceed with the repair.

If a part is needed, many common components - heating elements, pumps, dispenser mechanisms, spray arm assemblies - are available for next-day delivery, so a second visit for the actual repair is usually scheduled within a day or two. Labour for a standard repair typically runs between 60 and 100 pounds per hour, and most repairs take under an hour once the part is on hand.

Our engineers carry diagnostic equipment that can read fault codes from the machine's control board on brands including Bosch, Samsung, LG, Hotpoint, and Beko. This removes the guesswork and means you get an accurate quote rather than an estimate. Ask for the quote in writing before agreeing to any parts being ordered.

Across Hampshire, reputable appliance repair companies will also advise you if a repair isn't economically sensible. If the cost of repair is coming close to 50 percent of the replacement cost, it's worth having that conversation about whether to proceed.

Common Questions from Andover Homeowners

Why are my glasses coming out cloudy even after a full cycle?

Cloudy glasses are almost always caused by hard water leaving mineral deposits on the glass surface. This is particularly common in parts of Hampshire where water hardness is high. Make sure your dishwasher salt is topped up, increase the salt hardness setting if your machine allows it, and use a rinse aid. Running a descaling cycle once a month helps keep it under control. If the cloudiness is etching rather than limescale - permanent scratching from the heat - that's caused by over-washing delicate glassware and can't be reversed.

My dishwasher cleans the bottom rack fine but the top rack comes out dirty - what's causing it?

This is a classic sign of a blocked upper spray arm. The arm that serves the top rack sits underneath it and can become clogged with limescale or debris without you noticing. Remove it, clear the holes, and refit it. Also check that tall items on the lower rack aren't physically blocking the upper arm from rotating during the cycle. If the spray arm is clear but the problem persists, the water supply to the upper arm may have a pressure issue that an engineer should check.

How often should I be cleaning my dishwasher in Andover?

Given Hampshire's moderately hard water, a monthly maintenance routine is sensible. Clean the filter every two to four weeks, check and top up the salt every month or so depending on how heavily you use the machine, and run a dedicated dishwasher cleaning cycle monthly. The rinse aid reservoir typically needs refilling every three to four weeks with daily use. This kind of regular maintenance extends the life of the machine significantly and prevents the gradual decline in performance that most people experience.

Is it worth repairing a dishwasher or should I just replace it?

For most faults, repair is the better choice if the machine is under eight years old. A new mid-range dishwasher costs between 350 and 600 pounds installed, whereas most common repairs come in well below 200 pounds. The exception is when multiple components fail at once, or when the control board is at fault on an older machine - board replacements can push repair costs to a point where replacement makes more financial sense. An honest local engineer in Andover will give you a clear-eyed view on this before you commit to anything.