Almost every share-house I've lived in has had some nasty looking solids collecting inside. I always regret looking inside the kettle because a cup of tea never tastes quite as good after you've seen this:

enter image description here

What is that stuff? What's the physical process that causes it to collect and why is it usually concentrated around the heating element? Is it related to calcium in tap water, or is there any trick to prevent it appearing in your kettle? Is it dangerous to ingest and should be removed, or is it harmless?

  • $\begingroup$ You're wouldn't be living with Rick, Mike, Neil and Vyvyan Basterd would you? Just be thankful - the last kettle had a breakdown and exploded! $\endgroup$
    – WetSavannaAnimal aka Rod Vance
    Oct 29, 2013 at 2:37
  • 1
    $\begingroup$ As noted, it is limescale, which is typically white-ish (or if there are iron present, orange-ish). It's curious that it's yellow - could just be the camera... just wanted to offer that a natural way to clean the limescale (in addition to vinegar, which smells and might adversely affect your tea if you don't fully rinse it) is to use lemon or lime juice, which are also acidic in nature but would be a lovely addition to your tea. :-) $\endgroup$
    – Bunny
    May 26, 2021 at 8:18

1 Answer 1


This is limescale and you have it because your tap water is rich in minerals (mainly, calcium, as you note). You could remove these minerals with an ion exchanger, but you wouldn't to it with a tap water since these minerals give it a better taste. Limescale is not dangerous to ingest, but certainly not pleasant either (and I see on the photo that there is a slot for a mesh that should filter scales). Thick layer of limescale is also bad for the heating element – it hinders heat transfer to water and leads to overheating.

It is a good idea to remove limescale once in a while. You can dissolve limescale with any weak acid, like vinegar, but vinegar smells, so I suggest buying a descaling agent.


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