How Does Drinking Water Chlorination Work?
When chlorine disinfectants are added to water, free chlorine is formeda combination of hypochlorous acid and hypochlorite ion. While hypochlorous acid carries no electrical charge, hypochlorite ion carries a negative one. Of the two substances, hypochlorous acid is the more potent disinfectant. The pH, or the relative acidity of water, determines the ratio of hypochlorous acid to hypochlorite ion. Water treatment operators can adjust the pH during water treatment to make hypochlorous acid levels dominate hypochlorite levels. Another reason to maintain a predominance of hypochlorous acid during water treatment has to do with the fact that germ surfaces carry a natural negative electrical charge. For that reason, hypochlorite ion is repelled in the vicinity of germ surfaces, while hypochlorous acid can easily penetrate those surfaces. Favored by lower pH conditions, and its own electrical neutrality, hypochlorous acid pierces the barriers of germ slime coatings and resistant layers, des
