How to Descale Your Dishwasher

Limescale buildup is the silent killer of dishwashers. It reduces cleaning performance, causes white residue on glasses, and can eventually damage internal components. Regular descaling keeps your dishwasher running efficiently.

Why Descaling Matters

Hard water areas (most of the UK) cause calcium deposits to build up in your dishwasher. This affects:

• Spray arms: Blocked holes reduce water pressure
• Heating element: Limescale insulates the element, making it work harder
• Filters and pipes: Buildup restricts water flow
• Door seals: Can cause leaks over time

How Often Should You Descale?

• Hard water areas: Every 1-2 months
• Medium water areas: Every 2-3 months
• Soft water areas: Every 3-4 months

Not sure about your water hardness? Check your kettle – if it has visible limescale, your dishwasher has it too.

Method 1: White Vinegar

White vinegar is an effective, natural descaler that's gentle on your dishwasher.

Step 1: Empty the Dishwasher

Remove all dishes, racks, and the filter if easily accessible.

Step 2: Clean Visible Debris

Wipe around the door seal, spray arms, and filter area with a damp cloth. Remove any food particles.

Step 3: Add Vinegar

Place a dishwasher-safe bowl containing 250ml (1 cup) of white vinegar on the top rack.

Step 4: Run a Hot Cycle

Run the dishwasher on its hottest cycle, empty. The vinegar will circulate and break down limescale deposits.

Step 5: Fresh Rinse (Optional)

If you notice a vinegar smell afterward, run a short rinse cycle with nothing added.

Method 2: Citric Acid

Citric acid is more powerful than vinegar and leaves no smell.

Step 1: Get Citric Acid

Buy citric acid powder from supermarkets (often in the baking aisle) or online.

Step 2: Add to Detergent Dispenser

Put 3-4 tablespoons of citric acid powder in the detergent dispenser.

Step 3: Run Hot Empty Cycle

Run the hottest cycle available, with no dishes.

Method 3: Commercial Descalers

Brands like Finish and Calgon make dedicated dishwasher descalers. Follow the packet instructions – they're usually added to an empty hot cycle.

Descaling the Spray Arms

Don't forget to descale the spray arms separately:

1. Remove the spray arms (they usually twist off)
2. Soak in white vinegar for 30 minutes
3. Use a toothpick to clear blocked spray holes
4. Rinse and replace

Preventing Limescale Buildup

• Use rinse aid: It helps prevent water spots and mineral deposits
• Add salt: Keep your dishwasher salt topped up (even if you use all-in-one tablets)
• Run hot cycles: Occasional hot washes help prevent buildup

Signs You Need to Descale

• White film on glasses and dishes
• Cloudy glassware
• Dishwasher not cleaning properly
• Visible white deposits inside

When to Call an Engineer

If descaling doesn't improve performance, there may be:

• Blocked pipes requiring professional cleaning
• A faulty heating element
• Pump problems

Get a fixed price quote for expert dishwasher repair.