Why is hardness of water expressed as ppm?
The hardness of water is reported in grains per gallon, milligrams per liter (mg/l) or parts per million (ppm). One grain of hardness equals 17.1 mg/l or ppm of hardness. Hard water results when an excessive amount of calcium and magnesium are present. Total hardness is measured in grains per gallonof water (gpg) or milligrams per liter (mg/l). Grains per gallon (gpg) is a unit of weight for a volume of water, as is milligrams per liter (mg/l). Sometimes hardness is measured in parts per million (ppm). Parts per million (ppm) measures the unit(s) of a substance for every one million units of water. Milligrams per liter (mg/l) and parts per million (ppm) are roughly equal in water analysis. One gpg (1gpg) is equivalent to 17.1 ppm or mg/l. When conducting chemical analysis, laboratories usually measure hardness minerals in either grains per gallon (gpg) or milligrams per liter (mg/l)…
