Limescale manifests itself as chalky surface deposits. It inhibits heat conductivity, and clogs whistles of tea kettles, tubes in electric kettles and coffee makers, and hardens and clogs other parts that may need to move, such as important safety features like pressure release valves.

It is common in hard water, and to the degree of abundancy in naturally occurring calcium and magnesium. It is not common in softened water unless the softening system is not being properly maintained.

Frequency of de-scaling depends on frequency of use and degree of water hardness. Check regularly for surface deposits.
Add ½ cup of white vinegar to each quart of water and boil the mixture in the kettle for about 10 minutes. Rinse thoroughly.