•           Water Hardness

The presence of calcium (Ca2+) and magnesium (Mg2+) ions in a water supply is commonly known as "hardness." It is usually expressed as parts per million (ppm). Hardness minerals exist to some degree in virtually every water supply. The following table classifies the degree of hardness:

Hardness Level   Classification

mg/L    

0-17                  soft water

17-60                slightly hard water

60-120              moderately hard water

120-180            hard water

>180                 very hard water

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