How to Fix a Dishwasher Not Cleaning Properly
Last updated: 30 September 2026
Clean the filter, check the spray arms, use the correct detergent, and check the water temperature.
Overview
A dishwasher that leaves food debris or cloudy glasses is a common frustration. This guide covers diagnosing and fixing cleaning issues.
Step-by-Step Fix
Before beginning any repair, ensure you have isolated power or water supplies. Clear your workspace, gather standard hand tools, and wear appropriate personal protective equipment (PPE).
- First check the dishwasher filter. The filter is located at the bottom of the dishwasher under the lower spray arm. Twist and lift it out. Rinse it under running water and scrub with an old toothbrush to remove all food particles and grease. A clogged filter is the most common cause of poor cleaning.
- Inspect the spray arms for blockages. The spray arms are the rotating plastic arms above and below the dish racks. Use a toothpick or a thin wire to clear any food particles or limescale from the small holes. Rinse the spray arms under running water to confirm all holes are clear.
- Check the water inlet temperature. The dishwasher needs water at approximately fifty to sixty degrees Celsius to clean effectively. Run a hot tap in the kitchen before starting the dishwasher to ensure hot water reaches the appliance immediately. This is especially important on cold days.
- Use the correct amount of detergent. Too little detergent leaves food residue. Too much detergent can leave a cloudy film on glasses and dishes. Check the manufacturer recommendations for your water hardness. In hard water areas you may need more detergent or a rinse aid.
- Check the rinse aid dispenser and refill if empty. Rinse aid helps water sheet off dishes preventing water spots and improving drying. Most dishwashers have a rinse aid indicator light or a viewing window on the dispenser.
- Clean the dishwasher door seal. The rubber seal around the door can accumulate food debris and grime which can transfer to dishes. Wipe the seal with a damp cloth soaked in warm soapy water. Check for mould in the folds of the seal.
- Run a dishwasher cleaning cycle. Use a dedicated dishwasher cleaner or place a cup of white vinegar on the top rack and run a hot empty cycle. This descales the interior and removes grease buildup from hard to reach areas.
- Check the water hardness in your area. If you live in a hard water area limescale can build up inside the dishwasher reducing cleaning performance. Consider installing a water softener or using a dishwasher salt specifically designed for hard water.
- Ensure dishes are loaded correctly. Do not overcrowd the dishwasher. Leave space between dishes for water and detergent to circulate. Face soiled surfaces toward the spray arms. Do not block the spray arms with large items.
- If the dishwasher still does not clean properly after all these checks there may be a fault with the heating element or the water inlet valve. Call a qualified appliance technician to diagnose and repair the issue.
Common Symptoms & Diagnostic Resolutions
Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.
| Symptom / Code | Likely Root Cause | Recommended Resolution |
|---|---|---|
| Food remains on dishes | Blocked filter or spray arms | Clean the filter and clear the spray arm holes with a toothpick. Run a hot cycle with a dishwasher cleaner. |
| Cloudy glasses | Hard water or too much detergent | Use a rinse aid and adjust detergent amount. Consider using dishwasher salt in hard water areas. |
| Dishes not drying | Empty rinse aid or faulty heating element | Refill the rinse aid dispenser. If dishes still do not dry the heating element may be faulty. |
| White film on dishes | Limescale from hard water | Use a rinse aid and run a descaling cycle with vinegar. Install a water softener if the problem persists. |
Frequently Asked Questions
Why is my dishwasher not cleaning properly?
A blocked filter clogged spray arms incorrect detergent amount or low water temperature are the most common causes. Check each of these to identify the problem.
How often should I clean the dishwasher filter?
You should clean the filter monthly to prevent blockages. If you use the dishwasher daily clean it every two weeks. A clean filter is essential for effective cleaning.
Do I need to rinse dishes before loading?
Scrape off large food pieces but do not rinse dishes completely. Modern detergents need some food residue to activate. However too much food debris will clog the filter.
What is the best detergent for hard water?
Use a detergent that contains a built-in water softener or add dishwasher salt separately. Tablets with salt and rinse aid built in are convenient for hard water areas.