The sum of free chlorine
and combined chlorine.
Total chlorine is the sum of free chlorine and combined chlorine. Addition of chlorine is one method water treatment facilities use to disinfect and maintain water free of bacteria and harmful organisms. The presence of residual chlorine in drinking water indicates that: (1) a sufficient amount of chlorine was added initially to the water to inactivate the bacteria and some viruses that cause diarrheal disease; and (2) the water is protected from recontamination during storage.