Dishwasher Not Cleaning Properly? Here's What to Check

When a dishwasher stops cleaning effectively, most people assume it's broken. In reality, the most common causes are simple maintenance issues you can resolve yourself in under 30 minutes. Here's a systematic approach to diagnosing a dishwasher that's not cleaning properly.

Check 1: The Filter

This is the most common cause of poor dishwasher performance. The filter sits in the base of the machine (usually a round filter assembly you can lift out) and collects food particles. A clogged filter allows dirty water to recirculate over the dishes.

Fix: Remove the filter, rinse it under running water and use a soft brush to remove built-up debris. Run a cycle and check the results. If the filter is very blocked, soak it in warm soapy water for 10 minutes before brushing.

Check 2: Spray Arm Holes

The spray arms distribute water over the dishes through small holes. Mineral deposits and food debris can block these holes over time, reducing water pressure and coverage.

Fix: Remove the spray arms (they usually unscrew or unclip). Hold each arm up to the light and inspect every hole. Clear any blocked holes with a toothpick or a thin wire. Rinse under water, reattach and test.

Check 3: Loading Technique

Incorrect loading blocks water from reaching all surfaces. Plates facing outward rather than inward, bowls loaded flat, items blocking the spray arm rotation and cups that pool water are all common loading errors.

Fix: Ensure plates face inward and downward. Bowls tilt at 45 degrees. No item should overhang to block the spray arm's rotation. Check both spray arms spin freely after loading.

Check 4: Detergent and Rinse Aid

Using too little detergent, old detergent or the wrong type reduces cleaning performance significantly. Similarly, running out of rinse aid leads to water spotting and incomplete drying.

Fix: Use fresh dishwasher tablets or powder — not washing-up liquid. Check that the rinse aid dispenser isn't empty. Set rinse aid dosage higher if water spots persist.

Check 5: Water Temperature

Dishwashers need hot water to dissolve detergent and grease effectively. If your hot water system is set low (<55°C), the machine may not reach its target temperature.

Fix: Run the hot tap at the kitchen sink before starting the dishwasher to ensure hot water is in the pipes. Check your hot water system temperature setting.

Check 6: Limescale Build-Up

In Sydney, water hardness varies by area. Over time, mineral scale deposits can build up inside the dishwasher, on heating elements, spray arms and the walls of the cavity.

Fix: Run an empty cycle with a dishwasher cleaning tablet or add white vinegar to the bottom of the machine. For heavy scale, run several cleaning cycles.

When to Repair or Replace

If none of these fixes improve performance, the pump, heating element or water inlet valve may be faulty. At that point, compare the repair cost to replacement. Oceania Appliances stocks tested dishwashers with free Sydney delivery and a 3–6 month warranty. Contact us to explore your options.