How do I descale a kettle?

Limescale on a kettle element makes it slower and less efficient, and eventually shortens its life. It's calcium carbonate, so it dissolves in mild acid — which means the job is mostly waiting rather than scrubbing.

What you'll need

• White vinegar or citric acid powder
• Cloth or soft brush
• Rubber gloves (optional)

Step by step

1. Empty the kettle and check how much scale there is.A white film needs one treatment; thick flaky deposits may need two.
2. Fill with equal parts white vinegar and water to just cover the scale.Or a tablespoon of citric acid powder in 500ml of water, which works faster and doesn't smell.
3. Bring to the boil, then switch off and leave to stand for an hour.The standing time does the work. Boiling alone barely touches established scale.
4. Pour the solution away and scrub any remaining deposit with a soft brush.It should come away easily. If it doesn't, repeat the soak rather than scrubbing harder.
5. Rinse thoroughly, then boil with fresh water and discard — two or three times.This is the step people skip, and it's why the next cup of tea tastes of vinegar.
6. Clean or replace the limescale filter in the spout if there is one.It clogs and is easily overlooked. Most lift out for rinsing.
7. Repeat monthly in a hard water area.Regular light descaling is much easier than occasional heavy descaling.

Tips

• Citric acid is cheaper by volume, works faster and leaves no smell. It's sold for home brewing and cleaning.
• Emptying the kettle after use, rather than leaving water standing, noticeably slows scale formation.
• Only boil the water you need. Less water boiled means less scale deposited and less energy used.
• Never use a metal scourer on the inside — it damages the element coating and gives scale more to grip.

Common mistakes

• Boiling without the soak — Contact time is what dissolves scale. A quick boil barely touches it.
• Not rinsing and boiling out enough — Vinegar taste lingers persistently. Two or three discarded boils are needed.
• Scrubbing with an abrasive — It damages the element and the surface, and scale then forms faster.
• Mixing descaler with bleach — Acid plus chlorine releases toxic gas. Never combine cleaning products.

Questions people ask