White flakes floating in your herbal tea, a rough layer on the bottom and a kettle that takes longer and longer to heat the water: that's limescale. In much of Spain the water is hard and limescale builds up quickly, especially in autumn, when we make more tea and herbal infusions. You don't need any special product. Here's how to descale a kettle with what you already have in the kitchen: citric acid, vinegar or lemon, with specific quantities.
Where kettle limescale comes from and whether it's harmful
Limescale is mainly calcium and magnesium carbonate, which is deposited when hard water is heated. It isn't dangerous to your health in itself, but it does have its drawbacks:
- it acts as an insulator, so the water takes longer to boil and the kettle uses more electricity;
- it spoils the taste and look of tea, herbal infusions and coffee;
- a thick layer can shorten the life of the heating element.
How to descale a kettle with citric acid
This is the most effective method and the easiest, because citric acid leaves no smell.
- Pour about a litre of water into the kettle (or enough to cover all the limescale) and add two tablespoons of citric acid.
- Boil the water and leave it to stand for 20 to 30 minutes. If the layer is thick, boil it again.
- Pour the mixture away and remove any residue with a soft sponge. Don't use a metal scourer: it scratches the bottom and sides.
- Fill the kettle with clean water, boil it and pour it away. Repeat once more to get rid of any remaining acid.
Don't fill above the MAX line: as it boils, the mixture that dissolves the limescale foams up and can overflow.
Vinegar or lemon if you don't have citric acid
White vinegar dissolves limescale just as well. Mix it with water in a 1:2 ratio, bring it to the boil, leave it to work for an hour and follow the same steps as with citric acid. It has just one drawback: the smell. Afterwards, boil clean water two or three times and open the window.
Lemon works for thin layers. Slice one or two lemons, cover the slices with water, bring to the boil and leave to stand for half an hour. The kitchen smells wonderful, but lemon isn't enough for a thick layer of limescale.
What about bicarbonate of soda? It features in lots of tips, but it doesn't work on limescale because it isn't an acid. It's more useful for cleaning the outside of the kettle or getting rid of bad smells.
The filter, the outer casing and stovetop kettles
- The spout filter can usually be taken out. Leave it for half an hour in water with citric acid and rinse it.
- The outer casing can be cleaned with a damp cloth. Never immerse an electric kettle in water and keep the base away from moisture.
- Kettles for gas or induction hobs are descaled the same way, with citric acid or vinegar. If they're enamelled, don't scrub them with harsh scourers.
Common mistakes when descaling a kettle
- Scraping off the limescale with a knife or spoon. It's easy to scratch the bottom or damage the heating plate. It's better to dissolve thick limescale in two or three rounds than to scrape it off.
- Making tea straight afterwards. If you don't rinse well, the water will taste acidic. Boiling clean water twice is the bare minimum.
- Mixing products. Shop-bought descalers work well, but use them according to the instructions and don't add vinegar or citric acid to them.
- Ignoring the warning signs. If the kettle is very noisy, takes much longer than it used to or switches off before the water boils, it already has quite a lot of limescale. Don't put it off.
How often to descale and how to reduce limescale build-up
With hard water, descale the kettle roughly every two to three weeks; with soft water, every two to three months is enough. Don't wait until the layer is thick: a thin layer comes off in a quarter of an hour, while a thick one needs several rounds.
Not sure how hard your tap water is? Most water companies publish water analyses on their websites, including hardness. You can also find simple test strips in hardware shops and DIY stores.
Limescale builds up more slowly if you:
- don't leave water in the kettle overnight: pour away what's left and leave the lid open so it can dry;
- only boil the water you're going to use (and save electricity while you're at it);
- use water from a filter jug.
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