Hardness of water is measured as the concentration of the dissolved mineral salts of calcium and magnesium and can be further categorised as temporary (carbonate hardness) and permanent (non-carbonate hardness). When water containing these hardness salts is heated, the salts become less soluble, and precipitate (unlike many other dissolved minerals which actually become more soluble as water is heated).
The precipitated hardness results in troublesome deposits, which may cause many problems. The inconvenience and problems caused by calcium are well known, and are evident in all aspects of daily life (industry, commerce, hotels, home etc.). For example,
in steam and hot water boilers in cooling towers and humidification systems
water heaters, dishwashers and glass washers
coffee and espresso machines
in mixer taps, faucets, pumps thermostatic valves etc.
showerheads, bathroom surfaces, basins, toilets