Fill with equal parts white vinegar and water, or a tablespoon of citric acid in a full kettle, boil, then leave to stand for an hour. Citric acid is the better choice because it leaves no aftertaste.
Why scale forms
Hard water carries dissolved calcium and magnesium. Heating drives the reaction that makes those minerals come out of solution as a solid, which then settles on the hottest surface, meaning the element or the base. It is entirely harmless to drink, but it insulates the element, so a scaled kettle uses more energy and takes longer to boil.
The citric acid method, preferred
- Fill the kettle to about two thirds.
- Add one tablespoon of citric acid powder.
- Boil, then leave to stand for thirty minutes to an hour.
- Pour away, then rinse three times.
- Boil a full kettle of fresh water and discard it before making a drink.
The vinegar method
Equal parts white vinegar and water, boiled and left to stand for an hour, works identically. The only drawback is smell and residual taste, which needs two or three additional rinse boils to clear. If you use vinegar, do it in the evening so the kettle can air overnight with the lid open.
Cleaning the rest of the kettle
| Part | Method |
|---|---|
| Interior scale | Citric acid or vinegar soak |
| Spout filter | Remove it and soak separately, then brush |
| Stainless exterior | Bicarbonate paste, wiped along the grain |
| Fingerprints on steel | A drop of oil on a cloth, buffed off |
| Base contacts | Dry cloth only, never wet |
The spout filter is the part most people never remove. It is usually a small mesh cartridge that pulls straight out, and it holds the flakes that otherwise end up in a cup.
What not to do
- Do not scrape the element. Scratches give scale more surface to grip and it returns faster.
- Do not use bleach. Wrong chemistry for mineral deposits and hard to rinse from a drinking vessel.
- Do not submerge the base. The electrical contacts are there.
- Do not leave water standing. Emptying the kettle after each use slows scale formation considerably.
Slowing it down
Boil only what you need and empty the kettle rather than leaving water sitting in it. Standing water evaporates slightly and concentrates minerals, which accelerates deposition. In very hard water areas a filter jug used to fill the kettle roughly halves how often descaling is needed, though it does not eliminate it.