The Alkalinity of water is a measure of its capacity to neutralize acids. Alkalinity is imparted to water by bicarbonate, carbonate and hydroxide components. Bicarbonates represent the major form of alkalinity, since they are formed in considerable amounts from the action of carbon dioxide upon minerals in the soil.

Although there is no MCL* for alkalinity, a range of 30 to 100 mg/l of Calcium Carbonate is desirable for finished drinking water in order not to adversely affect taste and corrosivity. Alkalinity itself is not considered a health hazard.