Water Hardness is the amount of dissolved calcium and magnesium in the water which expressed as the equivalent amount of calcium carbonate in parts per million (mg/l). Hard water is high in dissolved minerals, both calcium and magnesium. Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals. General guidelines for classification of waters are: 0 to 60 mg/L (milligrams per litre) as calcium carbonate is classified as soft; 61 to 120 mg/L as moderately hard; 121 to 180 mg/L as hard; and more than 180 mg/L as very hard.

Related Definitions in the Project: The Property and Unit