A formula developed by Dr. W. F. Langelier to determine the scale forming or corrosive tendencies of water.

A measure of the overall corrosive or scale forming tendency of the water. The LSI calculation takes into account the water temperature, Total Alkalinity, Calcium Hardness, and pH of the water. An index below - 0.3 indicates that the water tends to be corrosive, while an index above + 0.3 indicates scale forming potential.

An index calculated from total dissolved solids, calcium concentration, total alkalinity, pH and solution temperature that shows the tendency of a water solution to precipitate or dissolve calcium carbonate.