What is Hard water?
[[Image:Dripping faucet 1.jpg|thumb|The hardness of the water results in a calcification]] '''Hard water''' is [[water]] that has a high [[mineral]] content (contrast with ''[[soft water]]''). The main components of these minerals usually are [[calcium]] (Ca<sup>2+</sup>) and [[magnesium]] (Mg<sup>2+</sup>) [[ion]]s. But there are also [[Solution|dissolved]] metals, [[bicarbonate]]s, and [[sulfate]]s. Calcium usually enters the water as either [[calcium carbonate]] (CaCO<sub>3</sub>) in the form of [[limestone]] and [[chalk]], or [[calcium sulfate]] (CaSO<sub>4</sub>) in the form of several other mineral deposits. The main source of magnesium is [[dolomite]] (CaMg(CO<sub>3</sub>)<sub>2</sub>). Hard water is generally not harmful and some hardness in water is a useful source of calcium for healthy [[bone]] development . == Other websites == *Alcoa Chemical, [http://www.alcochemical.com/products-markets/markets/LSI-Calculator.asp Langelier Saturation Index (LSI) Calculator] {{Webarchive|url=https://web.archive.org/web/20071201105027/http://www.alcochemical.com/products-markets/markets/LSI-Calculator.asp |date=2007-12-01 }} {{sci-stub}} [[Category:Water]]