How to Fix a Dishwasher That Isn't Cleaning Properly
Few things are more frustrating than opening your dishwasher after a full cycle to find dishes that are still dirty, greasy or gritty. Before calling a technician or replacing your dishwasher, most cleaning problems can be diagnosed and fixed at home. Here's a systematic guide to troubleshooting a dishwasher that isn't cleaning properly.
Step 1: Check the Most Common Causes First
Filter is Clogged
The number one cause of poor cleaning performance in modern dishwashers is a dirty or clogged filter. Most dishwashers made in the last 10 years have a self-cleaning or manual filter at the base of the dishwasher interior. A blocked filter restricts water flow and recirculates dirty water through the wash cycle.
Fix: Remove the lower rack, locate the filter (usually a cylindrical mesh assembly that twists out), remove it and rinse it under running water. Use a soft brush to remove any trapped food debris. Replace and test.
Spray Arms Are Blocked
Dishwasher spray arms have small holes through which water jets at high pressure. If these holes are blocked by food particles, lime scale or debris, water won't reach all parts of the load.
Fix: Remove the spray arms (usually unclip or unscrew from the centre). Hold each arm over a sink and rinse, using a toothpick or skewer to clear any blocked holes. Reattach and check they spin freely.
Incorrect Loading
Overloading the dishwasher or blocking the spray arms with large items is a very common cause of poor cleaning. Items that block the spray arms prevent water from reaching other items in the load.
Fix: Load dishes so spray arms can rotate freely. Place large items like pots and pans around the edges of the bottom rack, not blocking the centre spray arm. Don't nest bowls or cups — water needs to reach every surface.
Step 2: Check Your Detergent and Rinse Aid
Detergent Quantity and Quality
Using too little detergent, or old/damp detergent that has lost effectiveness, will result in poor cleaning. Dishwasher tablets are generally more reliable than powder, which can clump. Gel detergent is effective but can leave residue if the dispenser is overfilled.
Rinse Aid Level
Rinse aid isn't just for drying — it helps water sheet off dishes during the final rinse, preventing spotting and improving cleaning of the last stage of the wash. If your rinse aid indicator is empty, refill it.
Hard Water
Sydney has moderately hard water. Scale build-up from hard water reduces cleaning efficiency over time. If your dishes have a white chalky residue, hard water is the cause. Run a dishwasher cleaner or a cycle with citric acid to remove scale.
Step 3: Check Water Temperature and Water Supply
Dishwashers need hot water to effectively dissolve grease and activate detergent. Most dishwashers connect to cold water and heat it internally. If your water supply is cold and your dishwasher's heating element is failing, water won't reach the right temperature (usually 55–65°C for a wash cycle).
Test: At the end of a hot wash cycle, carefully open the door slightly — you should see steam escaping. If the interior feels barely warm, the heating element may have failed.
Step 4: Run a Service Wash
Run an empty cycle with a dishwasher cleaner or a cup of white vinegar placed in the bottom rack. This removes grease, scale and odour-causing bacteria from internal components.
When to Call a Technician
If cleaning performance doesn't improve after all the above steps, the issue may be a failing pump, a faulty heating element, or a water inlet valve problem. These require a technician to diagnose and repair.
When Replacement Makes Sense
If your dishwasher is more than 10 years old and repair costs approach $300 or more, replacement is often better value. Oceania Appliances stocks quality dishwashers with free Sydney delivery. Visit 2/14 Centre Place, Wetherill Park (open 7 days, 10am–8pm), call or WhatsApp 0422 489 492.