How is alkalinity typically measured?

Alkalinity is typically measured through a titration process where a standard solution of either sulfuric acid or hydrochloric acid is added to a water sample until a predetermined pH endpoint is reached. This method is effective because alkalinity primarily reflects the concentration of carbonate, bicarbonate, and hydroxide ions in the water, which contribute to its capacity to neutralize acids. The titration allows for the precise determination of this capacity by observing changes in pH as the acid is incrementally added. When the specific pH endpoint is identified, it indicates that the alkaline substances have been fully neutralized, permitting the calculation of alkalinity in terms of mg/L as calcium carbonate (CaCO3) or equivalent units.

Other methods mentioned do not accurately measure alkalinity. Total dissolved solids would reflect all dissolved substances in the water, not specifically those contributing to alkalinity. Assessing color and clarity provides information about water quality but does not indicate alkalinity levels. Gas chromatography is used for analyzing volatile compounds and gases, not for measuring alkaline substances in water.