Chlorine disinfection has been extremely effective in limiting the outbreaks of such water-borne diseases as typhoid fever, dystentary and cholera, virtually negating them from water supplies in America.
Chlorine is a very active element.
When added to a water supply it does not only disinfect it, but reacts with other chemicals in the water. An example of DPB production occurs when organic acids from decaying vegetation find their way into water supplies. THMs are linked to a number of serious health risks. Some are believed to cause cancer. One common THM, chloroform, is believed to retard fetus growth.