How to Descale a Dishwasher: Step-by-Step Guide for Australian Homes

How to Descale a Dishwasher: Step-by-Step Guide for Australian Homes

Hard water is a reality in many parts of Sydney and broader New South Wales. Over time, mineral deposits (calcium and magnesium) from hard water build up inside your dishwasher's heating element, spray arms and interior walls. This limescale reduces cleaning performance, increases energy consumption and can shorten the lifespan of the appliance. Regular descaling keeps your dishwasher performing at its best. This guide explains everything you need to know.

Signs Your Dishwasher Needs Descaling

• White chalky deposits visible on the interior walls, door seal or heating element
• Glasses and dishes coming out with a white film or cloudiness
• Longer cycle times or reduced cleaning performance
• A film on the bottom of the tub that doesn't wash away
• Spray arm holes partially blocked with mineral deposits

How Often Should You Descale?

In Sydney and other hard water areas of NSW, descaling every 1–3 months is recommended for heavily used dishwashers. For lighter use, every 3–6 months. If you use a rinse aid and dishwasher salt (in models with a salt reservoir), scale buildup is significantly reduced and you can descale less frequently.

What You'll Need

• A dishwasher descaler tablet or liquid (commercial products: Finish Dishwasher Cleaner, Durgol, Bosch descaler)
• Or: white vinegar and bicarbonate of soda (DIY method)
• Soft cloth or sponge
• Soft brush (toothbrush-size) for spray arm holes

Method 1: Commercial Descaler (Recommended)

1. Ensure the dishwasher is empty — no dishes, no cutlery
2. Place the descaler product as directed (usually in the cutlery basket or on the bottom rack, or poured into the base of the tub)
3. Run the hottest cycle available (usually "Intensive" or "Heavy" at 70°C+)
4. When the cycle finishes, wipe down the interior with a damp cloth
5. Remove and clean the filter as usual

Commercial descalers are formulated to dissolve limescale effectively without damaging seals or components. For heavily scaled machines, a second cycle may be needed.

Method 2: White Vinegar (DIY)

1. Ensure the dishwasher is empty
2. Place a dishwasher-safe bowl or cup filled with 250ml of white vinegar on the top rack
3. Run a hot cycle (60°C or higher)
4. After the cycle, sprinkle 1 cup of bicarbonate of soda on the bottom of the tub
5. Run a short hot cycle
6. Wipe down the interior when cool

Note: Vinegar is mildly acidic and effective at dissolving light limescale buildup. For heavy buildup, a commercial descaler will be more effective. Never pour neat vinegar directly onto rubber seals or the door gasket repeatedly, as prolonged acid exposure can degrade rubber over time.

Cleaning the Spray Arms

During your descaling session, remove the spray arms (usually unscrew or unclip) and check the small holes for blockages. Use a toothpick or thin wire to clear any blocked holes. Soak the spray arms in a vinegar-water solution for 20 minutes if heavily blocked, then rinse and refit.

Using Dishwasher Salt to Prevent Scale

Dishwashers with a water softener reservoir (most European brands including Bosch, Miele and Electrolux have one) use dishwasher salt to regenerate the internal water softener resin. This removes calcium and magnesium from the water before it enters the wash cycle, dramatically reducing scale buildup. If your dishwasher has a salt reservoir, keep it topped up. Dishwasher salt is not the same as table salt; it's available from supermarkets and appliance stores.

Need a New Dishwasher in Sydney?

If your dishwasher's performance can't be restored by descaling, it may be time for a replacement. We carry brand new and quality-refurbished dishwashers in Sydney at Oceania Appliances, all with warranty and free delivery. Visit our Wetherill Park showroom at 2/14 Centre Place (open 7 days, 10am–8pm), call or WhatsApp 0422 489 492, or email support@oceaniaappliances.com.au.