Why Is My Dishwasher Not Cleaning Properly?
A dishwasher that leaves food residue, grease or cloudiness on dishes is frustrating — but the cause is usually simple and fixable without a service call. This guide covers the most common reasons dishwashers fail to clean properly and what you can do about each one.
1. The Spray Arms Are Blocked
The spray arms are the rotating arms inside the dishwasher that spray pressurised water over your dishes. They have small holes that can become blocked with food debris, mineral deposits or broken glass. When these holes are partially or fully blocked, water can't reach all areas of the dishwasher effectively.
Fix: Remove the spray arms (they usually unscrew or unclip easily) and rinse them under a tap. Use a toothpick or thin wire to clear any blocked holes. Reattach and test a cycle.
2. The Filter Needs Cleaning
Modern dishwashers have a filter at the bottom of the tub that catches food particles to prevent them from recirculating. If this filter becomes clogged, wash performance drops significantly and the water starts to smell stale.
Fix: Remove the filter (usually found by twisting counter-clockwise at the bottom of the dishwasher tub), rinse under warm water and gently scrub with a soft brush. Clean the filter at least monthly.
3. You're Not Using Enough Detergent (or the Wrong Type)
Using too little detergent, or a detergent that's past its use-by date and has clumped, will result in poor cleaning. Liquid detergents can also absorb moisture and lose effectiveness if left in the dispenser between cycles.
Fix: Use a fresh dishwasher tablet or powder, following the manufacturer's recommended dose. For hard water areas like parts of Sydney, you may need a slightly higher dose. All-in-one tablets with rinse aid and salt are convenient and effective for most households.
4. The Water Temperature Is Too Low
Dishwashers need hot water to properly dissolve grease and activate detergent. If your hot water system is set too low, or the dishwasher isn't heating the water properly, cleaning performance suffers.
Fix: Run the hot tap at the kitchen sink for 30 seconds before starting a dishwasher cycle — this purges the cold water from the pipes and allows the dishwasher to fill with hot water from the start. If the dishwasher has a temperature setting, ensure it's set to at least 60°C.
5. Incorrect Loading
How you load your dishwasher has a significant impact on how well it cleans. Common mistakes include:
- Nesting cutlery or stacking bowls so water can't reach all surfaces
- Placing items over the detergent dispenser, blocking it from opening
- Placing tall items in the lower rack that block the upper spray arm from rotating
- Overloading the dishwasher
Fix: Load dishes facing the centre of the machine where water sprays from. Alternate spoons and forks in the cutlery basket so they don't nest. Make sure the spray arms can spin freely before starting a cycle.
6. The Rinse Aid Is Empty
Rinse aid doesn't just prevent spotting on glasses — it also helps water sheet off dishes during the final rinse, improving drying and preventing residue. Without rinse aid, some detergent and food residue can be left on dishes.
Fix: Check the rinse aid indicator and refill when empty. Set the rinse aid dispenser to a medium setting and adjust if spotting continues.
7. Hard Water Scale Build-Up
In areas with hard water, mineral deposits (limescale) build up on the heating element, spray arms, and interior walls of the dishwasher. This reduces heating efficiency and can leave a white film on dishes and glassware.
Fix: Run an empty cycle with a dishwasher cleaning tablet or a cup of white vinegar placed in the bottom of the tub. For ongoing prevention, use dishwasher salt in the salt compartment (if your machine has one) or use an all-in-one tablet that includes salt action.
When to Call for Service
If none of the above fixes resolve the issue, the problem may be mechanical — a faulty water inlet valve, a worn pump, or a malfunctioning heating element. If your dishwasher is more than 8–10 years old, the cost of repair may approach the cost of replacement. Oceania Appliances stocks quality dishwashers at competitive prices with free delivery across Sydney.