The year 2008 marks a milestone for the drinking water disinfection method that is far and away the most commonly used in the world – and has been hailed as one of the greatest human advancements in history.
In 1908, the Jersey City, N.J. Water Works became the first water system in the United States to practice large-scale chlorination on a permanent basis. On the 100th anniversary of this landmark event, an estimated 98 percent of U.S. municipal water systems treat water employing chlorine-based disinfectants.
While the systematic chlorination of American water didn’t begin until the early 20th century, records indicate that it had been utilized in England about a half century earlier. In 1854, a devastating cholera epidemic broke out in the London neighborhood of Soho. In one month’s time, more than 600 residents died. In those days, it was generally thought that cholera was caused by a miasma, or bad air. But John Snow, a physician and a pioneer of the science of epidemiology (the study of diseases in a population), postulated that cholera was a waterborne disease. When he discovered that nearly all the people who had died of cholera were drawing their drinking water from a public pump at the corner of Broad and Cambridge streets, he convinced local authorities to remove the handle from the pump. The epidemic came to an almost immediate end.
Snow also was the first to attempt to treat water with chlorine. In 1897, not long after Snow’s efforts, a German bacteriologist named Sims Woodhead used bleach solution to disinfect distribution mains in Kent, England following a typhoid outbreak. But it wasn’t until 1902 in Middelkerke, Belgium, that the first chlorination plant and continuous water chlorination took place.
After the successful use of chlorine disinfection in New Jersey, chlorination spread to other eastern states, and adoption by other cities and towns across the country soon followed. As a result, cholera, typhoid, dysentery and hepatitis A were virtually eliminated in the country. More than 200 million Americans receive chlorine-disinfected drinking water every day. And in 1997, Life magazine named water chlorination and filtration “probably the most significant public health advancement of the millennium.”
Chlorine’s most important attributes are its broad-spectrum germicidal potency and persistence in water distribution systems, providing residual protection against microbial re-growth. It destroys a variety of bacteria, viruses and protozoa including Salmonella and Shigella. It also kills pathogens and prevents their accumulation in fish, shellfish and other aquatic organisms. Chlorine is used to control taste and odor problems by oxidizing many naturally occurring substances such as algae secretions, decaying vegetation, hydrogen sulfide and ammonia. And chlorination is by far the most common method used globally to disinfect water and wastewater.
In recent years, a number of alternative drinking water disinfection methods have been developed including ozone, chlorine dioxide and ultraviolet radiation. Each disinfection technology has its own unique strengths and limitations, and according to Jeffrey Sloan, senior director of water and sustainability for the Chlorine Chemistry Division of the American Chemistry Council, “no single disinfection method is appropriate for all circumstances. In fact, a multi-step process may be appropriate to meet overall treatment goals.”
While the use of chlorine alternatives has grown significantly in recent years, Sloan believes chlorine will continue to play a vital role in the disinfection of water, particularly in underdeveloped parts of the world. “Because chlorine’s wide range of benefits cannot be provided by any other single disinfectant, chlorination will remain a cornerstone of waterborne disease prevention.”
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