How to Fix a Dishwasher That Isn't Cleaning Properly
A dishwasher that leaves food residue, cloudy glasses or greasy dishes is frustrating — but most cleaning problems have straightforward causes and fixes before you call a technician or consider replacing the machine. Work through these checks in order.
1. Check and Clean the Filter
The most common cause of poor dishwasher cleaning is a clogged filter. The filter sits at the bottom of the dishwasher tub and catches food debris. If it becomes blocked, water recirculation is restricted and dirty water is redistributed over the dishes.
To clean the filter: remove the lower rack, locate the cylindrical filter assembly at the bottom of the tub, twist and lift it out, rinse under warm running water and use a soft brush (an old toothbrush works well) to remove any debris caught in the mesh. Replace it firmly.
Frequency: clean the filter monthly if you use the dishwasher daily.
2. Check and Clean the Spray Arms
The spray arms distribute water throughout the dishwasher. The small holes in the spray arms can become blocked with mineral deposits or small food particles.
Remove the spray arms (usually they unscrew or unclip from their central mount), hold them under running water and use a toothpick or thin wire to clear any blocked holes. Run water through them and check that all holes spray freely before reinstalling.
3. Check Your Loading Technique
Poor loading is responsible for many cleaning complaints:
- Don't nest bowls or plates together — water can't reach surfaces that touch
- Face dirty surfaces toward the spray arms (down and inward)
- Don't block the spray arms by overloading tall items in the lower rack
- Place glasses and cups upside down in the top rack
- Put plastics on the top rack to avoid deformation and to get cleaner results
4. Check Your Detergent
Using the wrong amount or wrong type of detergent causes both over-sudsing (which reduces wash performance) and under-cleaning. Using too little detergent is a common cause of greasy dishes.
- Use a good-quality dishwasher detergent — budget brands perform noticeably worse
- Tablets (all-in-one) are easiest and usually give consistent results
- Don't use regular dish soap — it creates excessive foam and can damage the machine
- If you have hard water (common in some Sydney areas), add rinse aid and ensure the salt reservoir is filled for machines that have one
5. Run a Hotter Wash
Eco or quick cycles use lower temperatures that may not fully dissolve grease and detergent. If you've been defaulting to eco mode, run a full 65–75°C intensive cycle and check if cleaning improves. Regular use of full-temperature cycles also keeps the machine's interior cleaner.
6. Run a Machine Cleaning Cycle
Dishwashers build up grease, mineral deposits and limescale over time. Run a cleaning cycle with a dishwasher cleaner (Finish Machine Cleaner or similar) monthly or quarterly to remove internal buildup. If you don't have a dedicated cleaning tablet, fill the detergent compartment with white vinegar and run an empty hot cycle.
7. Check Water Temperature
If your dishwasher consistently underperforms, check that the hot water supply is reaching the machine at adequate temperature. Dishwashers perform best when incoming water is at least 50–55°C. If your hot water system is set very low or the dishwasher is at the end of a long run, it may start cycles with cold water.
When to Call a Technician
If you've worked through all the above and cleaning remains poor, the issue may be a faulty wash pump, a blocked water inlet, or a malfunctioning heating element. These require a qualified technician to diagnose and repair.
When to Replace Your Dishwasher
If your dishwasher is more than 10 years old and repairs are needed, compare the repair cost against the cost of a new machine. Modern dishwashers are significantly more energy and water efficient than machines from 10 years ago. At Oceania Appliances, we can help you identify a great replacement. Free delivery across Sydney. Visit 2/14 Centre Place, Wetherill Park, call or WhatsApp 0422 489 492, or email support@oceaniaappliances.com.au. Open 7 days, 10am–8pm.