Originally Answered: What is the background history of chlorine being used to clean our drinking water?
HOW SAFE IS OUR DRINKING WATER
I work in the area of water quality in my city (Tulsa, pop 400,00), and so I can tell you a bit about how we monitor tap water.
Water from the lakes or reservoir is piped into the city and the first thing that happens is it is filtered (using sand) to remove things like leaves and debris. Then it is filtered again to remove smaller particles of debris. Finally, chlorine is added.
The chlorine output is automatic and computerized and is continually tracked so that the level is consistent.
How safe is our water? We get 4-6 complaints per month about the odor, taste, or color of the water. We respond to every complaint and test the water for the chlorine level and the bacteria level (specifically e coli). The water has always tested OK. Always.
One call we get every once in awhile is that people will complain that their water smells like cat urine. The answer is always that they have had new carpeting put in and the chlorine in the air from when they run the water interacts with the chemicals in the new rug to create that odor. The water is safe, though.
HISTORY EFFECTIVENESS OF CHLORINE USE
Chlorination has played a critical role in protecting America's drinking water supply from waterborne infectious diseases for 90 years. The filtration and disinfection of drinking water has been responsible for a large part of the 50 percent increase in life expectancy in this century. That fact led Life magazine to recently cite the filtration of drinking water and use of chlorine as "probably the most significant public health advance of the millennium."
One of the first known uses of chlorine for water disinfection was by John Snow in 1850, when he attempted to disinfect the Broad Street Pump water supply in London after an outbreak of CHOLERA. In 1897, Sims Woodhead used "bleach solution" as a temporary measure to sterilize potable water distribution mains at Maidstone, Kent (England) following a typhoid outbreak.
Continuous chlorination of drinking water began in the early years of this century in Great Britain, where its application sharply reduced typhoid deaths. Shortly after this dramatic success, chlorination was begun in Jersey City, N.J., in 1908. Adoption by other cities and towns across the US soon followed and resulted in the virtual elimination of waterborne diseases such as CHOLERA, typhoid, dysentery and hepatitis A. Before the advent of chlorination for drinking water treatment, typhoid fever killed about 25 out of 100,000 people in the US annually, a death rate approximating that currently associated with automobile accidents.
Chlorine's most important attributes are its broad-spectrum germicidal potency and persistence in water distribution systems, providing residual protection against microbial regrowth. It also is used to control taste and odor problems by oxidizing many naturally occurring substances such as foul-smelling algae secretions, odors from decaying vegetation, hydrogen sulfide and ammonia.