How to descale a kettle and a coffee machine

Quick facts

Limescale is not a hygiene problem, it is an electricity bill. A layer on the element insulates it, so the kettle takes longer to boil and draws more power every time — and the thicker it gets, the faster new scale forms on top.

What you'll need

• citric acid, a tablespoon per litre of water
• or white vinegar diluted 1:1

• a soft cloth
• nothing abrasive at all

Step by step

1. Fill the kettle with the solution. A tablespoon of citric acid per litre of water, enough to cover the scale. Do not overfill — it foams as it boils.
2. Boil and switch off. One boil is enough to start the reaction.
3. Leave it for fifteen minutes. The acid does the work while it stands. Boiling repeatedly does not speed it up.
4. Pour it out and check. Thick scale may need a second round rather than scrubbing.
5. Wipe, do not scrape. A soft cloth only. Scratching the inside gives new scale more to hold onto, so next time it builds faster.
6. Boil clean water twice and discard it. Leftover acid is noticeable in the first cup of tea and ruins the taste of good water.

What to use — and what not to

How often to descale

In Bratislava, where the water is moderately hard, every one to two months. If a white film appears on the bottom sooner, shorten the interval — scale lengthens boiling time and raises consumption long before it becomes visible.

What to watch out for

• Never descale a kettle that is switched on. Fill, boil once, switch off, then let it stand.
• Do not use vinegar in a coffee machine unless the manufacturer allows it — it degrades rubber seals.
• The filter in the spout comes out on most kettles and holds more scale than the body does.
• If scale keeps coming back within two weeks, a filter jug costs less than the extra electricity.

When to leave it to a professional

A kettle is a ten-minute job you never need to outsource. Where it matters is everything descaled at the same time — taps, shower enclosure, the inside of a dishwasher and the washing machine drum — which is what a deep clean covers in one visit.