ABSTRACT
Fluoride is a pale, yellowish gas with a characteristic pungent odor. It belongs to the halogen family, and it is the most reactive nonmetallic element. Fluoride has an influence on bone metabolism in all organisms and dental health in humans. At a concentration of 1.0 to 2.00 ppm in the drinking water, fluoride is beneficial. Total hardness is commonly reported as equivalent concentration of calcium carbonate. Carbonate hardness is due to the presence of calcium and magnesium carbonates and bicarbonates. Noncarbonate hardness includes the calcium and magnesium sulfates, chlorides, and nitrates. Sulfates are often the only noncarbonate hardness compounds present. The preferred method for determining hardness is to compute it from the results of separate determinations of calcium and magnesium. If the sum of the normal carbonate and bicarbonate alkalinities is equal to the total hardness, the carbonate hardness is also equal to the total hardness.
