How to Descale a Dishwasher: Step-by-Step Guide
If your dishwasher is leaving white residue on glasses, running less efficiently or showing scale build-up around the door seal and spray arms, it's time to descale. Here's how to do it properly.
Why Descaling Is Important
Hard water contains calcium and magnesium minerals that build up inside your dishwasher over time. This limescale reduces heating efficiency, blocks spray arm jets and shortens the lifespan of internal components. Sydney's water is moderately hard, making descaling a periodic necessity.
What You'll Need
- White vinegar or a commercial dishwasher descaler
- Baking soda (optional)
- A dishwasher-safe bowl or cup
Method 1: White Vinegar (Natural)
- Remove all dishes from the dishwasher
- Place a dishwasher-safe cup or bowl filled with 240ml of white vinegar on the top rack
- Run a hot cycle (60°C or higher) with no detergent
- The vinegar dissolves light to moderate mineral deposits
For extra freshness, after the vinegar cycle, sprinkle one cup of baking soda on the bottom of the dishwasher and run a short hot cycle.
Method 2: Commercial Dishwasher Descaler
- Remove all dishes
- Follow the product instructions (most go in the detergent compartment or on the base of the dishwasher)
- Run the recommended cycle (usually 60°C or the most intensive cycle)
Commercial descalers like Finish Dishwasher Cleaner, Durgol or branded products from Bosch and Miele are more effective than vinegar for heavy scale build-up.
Clean the Spray Arms
Remove the spray arms (usually unscrew or unclip) and soak them in vinegar for 15–20 minutes. Use a toothpick to clear any blocked jets. Rinse and reattach.
How Often to Descale
Once every 1–3 months, depending on your water hardness and how frequently you use the dishwasher. If you notice white film on glassware, increase frequency.
Prevent Scale Build-Up
- Always use rinse aid — it actively reduces water spotting and scale
- Keep the salt reservoir topped up (for dishwashers with a water softener)
- Use a wash temperature of at least 55°C
When to Upgrade
If descaling doesn't improve results and your dishwasher is over 10 years old, it may be time for a new model. Modern dishwashers are significantly more energy and water efficient. Browse our range at Oceania Appliances.