Final answer:
Water containing high concentrations of calcium, magnesium, or iron is called hard water. It can cause problems in water heaters and pipes. Water softening techniques can remove these minerals and reduce scale build-up.
Step-by-step explanation:
Water containing high concentrations of calcium, magnesium, or iron is called hard water. Hard water is formed when minerals like calcium carbonate, CaCO3, dissolve in natural water bodies such as lakes, rivers, and underground waterways. It is the presence of these minerals that gives hard water its characteristic properties.
When hard water is heated, calcium carbonate can precipitate and form a deposit called limescale. This can cause problems in water heaters and can also impede the function of pipes, requiring more energy to heat water or even blocking water pipes.
In order to remove calcium, magnesium, and other metal cations in hard water, water softening techniques such as lime softening, ion-exchange resins, or reverse osmosis membranes can be used. Softening the water reduces scale build-up in pipes and fittings, extends the lifetime of plumbing, and requires less soap for cleaning.