Scaling in kettles is caused by hard water, where calcium or magnesium are dissolved in water. As the kettle boils, insoluble calcium carbonate will form from the water which spreads across the appliance. This is presented as limescale which will remain in the kettle until it is thoroughly cleaned.

Does hot water cause more limescale?

Limescale will build up faster on hot water appliances. This is because hot water evaporates off a surface much quicker than cold water would. If you live in a soft water area, you won't have an issue with limescale, however you may find that your taps start to erode over time.

What is the white stuff after boiling water?

Have you ever noticed a white residue on the inside of your kettle after boiling water? If you have, there's nothing to worry about. That white substance is calcium, which exists as a dissolved mineral in water.