How to Descale a Dishwasher: Step-by-Step Guide

How to Descale a Dishwasher: Step-by-Step Guide

Limescale (calcium carbonate deposits) is the natural enemy of dishwashers. Over time, minerals from tap water build up on heating elements, spray arms, filters and the interior surfaces of your dishwasher. This reduces wash efficiency, causes spotty glassware, increases energy use and shortens the appliance's lifespan. Regular descaling — every 3–6 months depending on your water hardness — keeps your dishwasher performing at its best.

Signs Your Dishwasher Needs Descaling

• White or grey deposits on the interior walls, door or racks
• Cloudy, spotted or filmy glasses after a wash cycle
• Reduced water pressure from spray arms
• Longer cycle times or reduced heating performance
• White crusty deposits around the door seal or filter

What You Need

• Dishwasher descaler/cleaner (commercial product) OR
• White vinegar (500mL–1L for a natural option)
• Citric acid powder (another natural alternative)
• Microfibre cloth
• Old toothbrush

Method 1: Commercial Dishwasher Descaler

Products like Finish Dishwasher Cleaner, Calgon or brand-specific cleaners (Bosch Dishwasher Cleaner, Miele Dishwasher Cleaner) are the most effective. These contain descaling agents specifically formulated for dishwashers.

1. Remove all dishes from the dishwasher
2. Place the cleaner product in the dishwasher according to the product instructions (some go in the detergent dispenser, some are placed upside-down in the bottom rack)
3. Run the hottest available programme (usually 65°70°C)
4. Open the door and inspect — repeat if heavy scale is still visible

Method 2: White Vinegar

White vinegar's acidity dissolves calcium deposits effectively and is a low-cost, chemical-free option.

1. Remove all dishes
2. Pour 500mL–1L of white vinegar into a dishwasher-safe bowl or measuring jug and place it on the bottom rack
3. Run a hot cycle (60°C+) without detergent
4. Allow the cycle to complete — the steam and hot vinegar will descale the interior

Note: Do not use vinegar in the detergent dispenser. The concentrated acid can damage rubber seals and components over time if used too frequently. Limit vinegar descaling to once per month.

Method 3: Citric Acid Powder

Citric acid is a highly effective descaler used in many commercial products. Add 2–3 tablespoons to the bottom of the dishwasher (not the detergent dispenser) and run a hot cycle. Very effective for heavy scale build-up.

Cleaning the Filter After Descaling

Always clean the filter after descaling:

1. Remove the filter (usually twist-and-lift from the base of the wash chamber)
2. Rinse under warm water to remove loose debris
3. Soak in warm white vinegar for 10–15 minutes if scale is present
4. Scrub gently with an old toothbrush
5. Refit the filter

Cleaning the Spray Arms

Remove spray arms (they usually unclip or unscrew) and check the holes for blockages. Soak in white vinegar, then use a toothpick to clear any blocked holes. Rinse and refit.

Preventive Maintenance

• Use dishwasher salt (in models with water softeners) — top up monthly
• Use a quality rinse aid every cycle
• Descale every 3 months (more often in hard water areas)
• Clean the filter monthly

Need a New Dishwasher?

If your dishwasher is old and descaling doesn't restore performance, it may be time to upgrade. Oceania Appliances stocks the full range of Bosch, Miele, AEG, Electrolux and Fisher & Paykel dishwashers. Free delivery across Sydney. Visit 2/14 Centre Place, Wetherill Park, call or WhatsApp 0422 489 492, or email support@oceaniaappliances.com.au.