The water supplied through our water systems contains calcium and magnesium minerals, which are responsible for its hardness. Heating up the water, the hardness produces a chemical reaction that forms calcium and magnesium carbonate (commonly called limescale), and carbon dioxide. Their amount and quality varies depending on the geographic area, producing water with a different “hardness". Limescale is the main factor that determines the scaling that builds up in the pipes and system, especially when the water is heated. Limescale is the result of the fact that these hardness salts settle when the water evaporates. The harder the water is, the more frequent and stronger is the limescale phenomenon.
Do you want to know more? Look at the video THE WORST ENEMY OF GLASS: LIMESTONE or go to the page TPA