Contrary to its name, limescale is actually a build-up of calcium. When hard water containing high levels of calcium is evaporated, the white, chalky limescale will remain. Electric kettles that evaporate hard water on a regular basis will have significantly more limescale accumulation. Luckily, it is easy to remove limescale in an electric kettle using only a few household items.
Fill the electric kettle halfway full with one part water and one part white vinegar. The white vinegar will slowly dissolve the limescale from inside the kettle.
Bring the vinegar solution to a rolling boil. Turn the heat off and allow the liquid to sit in the kettle overnight. This will give the mixture enough time to dissolve most of the limescale.
Pour the vinegar water out of the electric kettle. Fill it a quarter of the way full with cool water and swish it around, then pour it back out.
Use steel wool to scrub the inside of the electric kettle. Most of the limescale should come out at this point.
Rinse the electric kettle with cold water to remove the smell of vinegar. If any limescale remains inside, repeat the procedure as necessary.
A scouring pad can be used in place of steel wool to clean the inside of the electric kettle.
Never leave the electric kettle turned on overnight, as this is a fire hazard.