How to Descale a Washing Machine (Step-by-Step UK Guide)

Quick Answer

To descale a washing machine, run an empty hot cycle at 60–90°C with a citric acid-based descaler tablet in the drum. Wipe the door seal and detergent drawer afterwards, then run a short rinse cycle to flush loosened deposits. Repeat every two to four weeks if you live in a hard water area.

Signs Your Washing Machine Needs Descaling

Limescale builds up slowly, so the problems it causes tend to creep in rather than arrive overnight. Most people notice the laundry first: towels come out stiff, colours look dull, and clothes carry a faint musty smell even after a full wash. These are all signs that mineral deposits are interfering with how your machine cleans.

Check the rubber door seal. If you can see white, chalky residue around the folds, that same buildup is almost certainly coating the drum interior and the heating element you cannot see. A heavily scaled heating element takes longer to reach temperature, which means longer cycle times and higher electricity bills.

Other common signs include:

• White or grey flakes on dark clothing
• Detergent residue left on fabrics (scale prevents proper dissolving)
• A persistent damp or sour smell from the drum
• The machine taking noticeably longer to complete a cycle
• Error codes related to heating or drainage on newer models

If you are not sure whether your area has hard water, the Consumer Council for Water provides postcode-based lookup tools. Over 60% of English households are supplied with hard or very hard water, according to British Geological Survey data. You can also check our UK hard water map for a visual breakdown by region.

What You Will Need

Descaling a washing machine does not require specialist equipment. Gather the following before you start:

• A citric acid-based descaler tablet (or pure citric acid powder, roughly 100–150g per cycle)
• A clean microfibre cloth
• An old toothbrush for the door seal and detergent drawer
• A small bowl or basin for soaking the detergent drawer

Avoid using bleach at the same time as a descaler. Bleach is useful for sanitising, but it does not dissolve limescale. The two serve different purposes and should be used in separate cycles.

Step-by-Step Descaling Process

Step 1: Empty the Drum Completely

Remove all clothing, loose items, and anything sitting in the drum. Check the rubber door seal for trapped coins, hair grips, or debris. These can scratch the drum during a hot empty cycle and should be cleared out first.

Step 2: Clean the Detergent Drawer

Pull the detergent drawer out fully. Most drawers release by pressing a tab at the back of the softener compartment. Soak it in warm water with a small amount of citric acid powder for 15–20 minutes, then scrub with the toothbrush to clear any caked-on residue. Rinse and set aside to dry. While the drawer is out, wipe inside the drawer housing with a damp cloth.

Step 3: Add the Descaler

Place your descaler tablet directly into the drum, not in the detergent drawer. Direct drum placement ensures the active ingredients make full contact with the drum walls and reach the heating element below. If you are using citric acid powder instead, measure 100–150g and scatter it across the base of the drum.

Step 4: Run a Hot Cycle (60–90°C)

Select the hottest wash programme your machine offers. A 90°C cotton cycle is ideal. The combination of heat and citric acid dissolves calcium carbonate deposits on the drum, heating element, pipes, and pump. Do not add any detergent or fabric softener to this cycle.

Let the full cycle complete without interruption. Some people pause midway through, thinking a soak helps. With citric acid, continuous circulation is more effective because it keeps loosened deposits suspended in the water rather than letting them resettle.

Step 5: Wipe Down the Door Seal

Once the cycle finishes, open the door and wipe around the entire rubber seal with a damp microfibre cloth. Pay attention to the lower folds where water pools. You will likely see grey or brown residue on the cloth. This is dissolved limescale mixed with trapped grime. Keep wiping until the cloth comes away clean.

Step 6: Clean the Filter

Locate your machine's pump filter (usually behind a panel at the bottom front). Place a shallow tray or towel beneath it, twist the cap anticlockwise, and let the residual water drain. Remove any debris caught in the filter, rinse it under the tap, and replace it. This step catches any loosened scale fragments before they cause a blockage.

Step 7: Run a Short Rinse Cycle

Run a quick rinse or spin-only cycle to flush any remaining descaler residue from the system. This ensures your next load of laundry is not exposed to leftover cleaning agents.

How Often Should You Descale?

The frequency depends on your water hardness. As a general guide:

• Hard water areas (over 200 mg/l calcium carbonate): Every two weeks to once a month
• Moderately hard water (100–200 mg/l): Every one to two months
• Soft water areas (under 100 mg/l): Every three to six months, or when you notice buildup

Consistency matters more than intensity. A regular descaling routine prevents the thick, hardite-like deposits that are difficult to shift in a single cycle. For a full maintenance calendar, see our washing machine maintenance schedule.

Citric Acid vs White Vinegar for Descaling

Both citric acid and white vinegar are acidic, but they are not equally effective at removing limescale from a washing machine.

Citric acid (at concentrations of 10–30%) reacts directly with calcium carbonate to produce calcium citrate, water, and carbon dioxide. The reaction is efficient and leaves minimal residue. Purpose-made descaler tablets typically pair citric acid with sodium polyacrylate, a dispersant that prevents loosened scale from resettling on surfaces. This means the limescale actually leaves the machine rather than just moving around inside it.

White vinegar (acetic acid, usually 5–8%) is weaker. You would need a large volume to match the descaling power of a single citric acid tablet, and even then, acetic acid can degrade rubber seals and door gaskets over time. Several washing machine manufacturers, including Bosch and Miele, advise against using vinegar in their machines for this reason.

Vinegar also leaves a lingering smell that can take multiple wash cycles to clear. Citric acid is virtually odourless.

The practical conclusion: citric acid is more effective, safer for machine components, and easier to use. Vinegar works in a pinch, but it is not the better long-term option.

How to Prevent Limescale Returning

Descaling removes existing buildup, but without ongoing prevention, the deposits return within weeks in hard water areas. A few habits make a noticeable difference:

• Use the right amount of detergent. Overdosing does not improve cleaning. Excess detergent creates residue that limescale clings to. Follow the dosing guide on your detergent for your water hardness level.
• Run a hot cycle regularly. Most modern wash routines sit at 30–40°C, which is fine for clothes but does nothing to prevent mineral buildup. Run at least one 60°C cycle per week.
• Leave the door and drawer open after every wash. Moisture sitting in a warm drum encourages both limescale deposits and mould growth. Let it air dry.
• Wipe the door seal after each use. Takes 10 seconds and stops the seal becoming a breeding ground for limescale and mildew.
• Use a preventative descaler on a schedule. A fortnightly descaling cycle in hard water areas stops scale before it becomes a problem.

For more detail on maintaining your machine in hard water conditions, read our guide on how to clean your washing machine in UK hard water areas.

Frequently Asked Questions

Can I use vinegar to descale my washing machine?

You can, but citric acid is the better choice. White vinegar is a weaker acid and requires a much larger quantity to achieve the same result. It can also degrade rubber door seals with repeated use and leaves a strong smell that persists for several wash cycles. Citric acid is more effective, odourless, and gentler on machine components.

Will descaling damage the rubber seals?

Citric acid-based descalers are safe for rubber seals, plastic parts, and stainless steel drums. Purpose-made descaler tablets often include sodium silicate, which forms a protective layer on metal surfaces during the cleaning process. Avoid using neat hydrochloric acid or industrial-strength descalers, which can cause damage.

How do I know if I have hard water?

Check your water supplier's website or use the postcode lookup tool on the Consumer Council for Water's site. You can also look for physical signs: white deposits on taps and showerheads, scum floating on tea, and soap that does not lather easily. Water above 200 mg/l calcium carbonate is classified as hard. Most of south-east England, the Midlands, and East Anglia fall into this category.

Can I put a descaler tablet in the detergent drawer instead of the drum?

Placing the tablet directly in the drum is more effective. It ensures the descaler makes contact with the drum walls from the start of the cycle and reaches the heating element below. Tablets placed in the detergent drawer are dissolved and flushed in with water, which dilutes them before they reach the areas that need the most attention.

How long does a descaling cycle take?

A standard hot cotton cycle at 90°C typically runs for 90 minutes to two hours, depending on your machine. There is no need for a special programme. Just select the hottest cycle available, add the descaler to the drum, and let it run to completion.

Is descaling the same as cleaning a washing machine?

Not quite. Descaling specifically targets mineral deposits (limescale) using an acid-based product. A general clean may also address mould, bacteria, detergent residue, and odours. Both are important, but they tackle different problems. In hard water areas, descaling should be the foundation of your maintenance routine, with additional cleaning steps layered on top.

Do front loaders need descaling more than top loaders?

Both types are affected by limescale, but front loaders tend to show symptoms sooner. The horizontal drum and rubber door seal create more surfaces where moisture and minerals collect. Top loaders drain more completely after each cycle, which can slow buildup slightly. Regardless of type, regular descaling is recommended in hard water areas.