What causes limescale?

Nothing will put you off your cup of coffee more than taking a peek inside the kettle and catching an eyeful of white, chalky flakes floating around in the water you’re about to drink.

This article will help you identify limescale, understand what it is and what causes it, and find a way to get rid of it.

What is limescale?

Limescale is the result of a long process, starting when it rains.

When rainfall descends, it picks up CO2 (carbon dioxide), making the water slightly acidic. By the time it reaches the ground, the water has become a natural solvent, and as it seeps underground, it dissolves minerals along the way and becomes ‘hard’. Hard water generally contains four hard minerals:

  • Calcium
  • Magnesium
  • Carbonate
  • Sulfate

Every water supply has some dissolved mineral content in it.

The limescale occurs when energy is applied to the water (such as when you boil your kettle), which causes minerals to drop out of the solution and settle on surfaces.

Is limescale bad for your health?

This is a hotly debated topic but the general consensus is that consuming the limescale from your kettle is not toxic because it’s predominately formed of calcium salt crystals that, although can be absorbed by the gut in small amounts, will usually pass straight through the digestive system.

To confirm this point, the World Health Organization (WHO) state: “There does not appear to be any convincing evidence that water hardness causes adverse health effects in humans.”1 The National Research Council even go as far to say that consuming limescale can be beneficial, reporting: “Hard water can partly satisfy ones calcium and magnesium dietary needs. In instances where calcium and magnesium concentrate are very high, this can be the primary magnesium and calcium contributor to the human diet.”

However, we do not advise resorting to a limescale-ridden kettle to maintain your daily magnesium and calcium quotas!

Can limescale break appliances?


The main problem is when limescale builds up around the fittings inside your appliances, causing them to malfunction. For instance, if limescale forms inside the heating element of your washing machine, it’ll act as an insulator, and a premature breakdown is likely if the element becomes hotter than usual. Additionally, limescale-coated heating elements reduce a machine’s efficiency, which means you’ll need more electricity and more washing detergent to ensure your clothes are cleaned effectively.

The limescale problem doesn’t stop at the washing machine either, as limescale can stain your bath and sink, and a build up in your central heating system, dishwasher, or other heated appliances, can severely shorten their lifespans. Similar to the way in which our arteries can become clogged up with cholesterol, the hoses and pipes within heated water appliances may fur up too, so it’s important to keep them healthy, particularly if you live in a hard water area.

How can I prevent and get rid of limescale?

There are plenty of water softening products on the market, most notably Calgon. Many consumers want to know if washing machines really do ‘live longer with Calgon’ as the advert says, and the short answer is yes, because it does use specific ingredients to soften hard water.

However, detergents usually contain these ingredients too, so water softeners don’t do anything that your usual detergent doesn’t do, providing you are using the correct measurement for the level of hard water in your area and the extent of soiling to your clothes.

If you live in a soft water area, you’re unlikely to encounter limescale problems, thus using a water softener as a preventative measure is not necessarily needed. Overdosing a washing machine with softener is not only a waste of money, but it can also result in excessive soap suds and poor wash quality, plus the detergent may not be able to fully dissolve so it won’t be able to do its job effectively.

London is considered a hard water area (see full UK hard water map here) but if you want an accurate reading, most water companies will send you a free testing pack for you to test your supply if you contact them.

If you are experiencing problems with your water appliances and think that limescale may be the issue, you can call out one of our experienced engineers to diagnose the problem and replace the necessary parts to restore your machine to new. Speak to us on 020 3773 5755 or contact us online today.

1 Tackling & Removing Limescale, 2015. [Online] Available at: https://tacklinglimescale.wordpress.com/2014/03/12/the-effects-of-limescale-on-health/. [Accessed 8th September 2015].

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