Original: English CHLORINE

Chlorination has played a critical role in protecting drinking water supplies from waterborne infectious diseases for nearly a century. The chlorination of drinking water has been widely recognized as one of the most significant advances in public health protection. Filtration and chlorination have virtually eliminated waterborne diseases such as cholera, typhoid, dysentery and hepatitis A in developed countries. In the United States over 98 % of water supply systems that disinfect drinking water use chlorine because of its germicidal potency, economy and efficiency. In addition, chlorine-based disinfectants are the only major disinfectants with the lasting residual properties that prevent microbial regrowth and provide continual protection throughout distribution from the treatment plant to the home. This paper discusses chlorine advantages and disadvantages and updates the reader on current knowledge about disinfection byproducts. 1. History Chlorination has played a critical role in protecting drinking water supplies from waterborne infectious diseases for 90 years. Filtration and chlorine disinfection of drinking water have been responsible for a large part of the 50 percent increase in life expectancy in developed countries during the 20th century. This fact led Life magazine to recently cite drinking water filtration and chlorination as "probably the most significant public health advance of the millennium." One of the earliest uses of chlorine as a disinfectant was introduced by Dr. Ignaz Semmelweis in 1846. While serving at a Vienna hospital, he determined that child bed fever and other infections were being transmitted among patients by doctors who failed to wash their hands between examinations. He instituted a disinfecting procedure requiring physicians to wash their hands with soap and chlorine water. One of the first known uses of chlorine for water disinfection occurred in 1854 when Dr. John Snow attempted to disinfect the Broad Street Pump water supply in London 2after an outbreak of cholera. Following a typhoid outbreak in 1897, Sims Woodhead used “bleach solution ” as a temporary measure to sterilize potable water distributio