Water, Hard

Name:
Water, Hard
Detailed information:
Water containing low percentages of calcium and magnesium carbonates, bicarbonates, sulfates, or chlorides as a result of long contact with rocky substrates and soils. Degree of hardness is expressed either as grains per gallon or parts per million (ppm) of calcium carbonate (1 grain of CaCO₃ per gal is equivalent to 17.1 ppm). Up to 5 grains is considered soft; more than 30 grains is very hard. Hardness may be temporary (carbonates and bicarbonates) or permanent (sulfates, chlorides). Treatment with zeolites is necessary to soften permanently hard water. Temporary hardness can be reduced by boiling. These impurities are responsible for boiler scale and corrosion of metals on long contact. Hard waters require use of synthetic detergents for satisfactory sudsing.See Zeolite.