DEFINITION OF HARDNESS

The hardness in your water supply is the total amount of ions that have have lost divalent cations and dissolved int he water and formed harder water. Magnesium and calcium are the two most common divalent cations, along with others such as iron, aluminum, and manganese that make up water hardness. Usually areas that harbor greater degrees of human activity such as mining locations produce water hardness as a result of higher concentrations of ions.

Water hardness is determined by parts per million and can be found by dividing the overall hardness level by 17.1 to get hardness in grains per gallon.