Who first used chlorine in a swimming pool?

What is the history of pool chlorination?

When was chlorine first used to sterilize swimming pools?

Why do we use chlorine?


History of Chlorine as a Swimming Pool Sanitizer.



"To most people swimming pools conjure summer afternoons dedicated to carefree indulgences like lime daiquiris and a satisfying bad novel.   Pools are pleasure ponds and symbols of suburban arcadia." (S. Garbarino, The Pool in Film: Deep and Lovely And Full of Sharks, New York Times, 2003, July 27, ST1)


A Complete History of Chlorine Use Has Been Submitted to the Bulletin for the History Of Chemistry, a publication of the American Chemical Society.


The purpose of this page is to provide a quick answer to the question, who invented chlorine for swimming pools?


It is commonly believed that the ancient Romans were the inventors of the swimming pool or public baths, they were actually latecomers to the idea.  For much of western history, bathing was performed only infrequently and very few people even knew how to swim.  The nineteenth century British enjoyed public baths in India and Japan and they brought the modern swimming pool back home to England.


The first public swimming pool to open in the United States was in the town of Brookline, Massachusetts, in 1887. 


Prior to the introduction of sterilization technologies most swimming pools were filtered to keep them somewhat clean and the water was changed frequently.


Chemical producers began making Bleaching Powder in the 1890s when cheap electricity from central generating stations became available.


Bleaching powder is calcium oxychloride (CaOCl2) although it is often erroneously called calcium hypochlorite [Ca(OCl)2 * 4H2O].  Bleaching powder was made by reacting chlorine gas with lime.


The chlorine was supplied as a by-product of the electrolytic production of sodium hydroxide.  Passing an electric current through a concentrated solution of sodium chloride liberates chlorine and hydrogen as gasses and leaves behind concentrated sodium hydroxide.  Sodium hydroxide was commonly known as caustic soda.  It was, and still is, used in a great variety of industrial processes including soap and glass manufacture.


Credit for the first use of chlorine to disinfect potable water goes to the British scientist Sims Woodhead who used "bleach solution" as a to sterilizing agent during a typhoid outbreak in Maidstone, Kent.


The first regular use of chlorine for potable water treatment was at Jersey Citys Boonton Reservoir, in Boonton, New Jersey in 1908.


By the early 1900's waterworks engineers had mastered the use of chlorine and filtration.  Educators and health professionals appreciated the value of swimming for physical fitness.  All of the elements of the modern swimming pool were in place.


As near as the author can determine, the first attempt to sterilize a pool in the United States using chlorine was at Brown University in 1910.  The 70,000-gallon Colgate Hoyt Pool was chlorinated by graduate student John Wymond Miller Bunker.


(W. Bunker, The Hygenie of the Swimming Pool, American Journal of Public Hygiene, 1910 (20:4), 810-812.)


Bunker applied hyperchlorite of lime (sic) to 2 liters of pool water at a concentration of 1 ppm.


According to the New York Times, the pool remained sterile for four days.


Shortly after the Brown University experiment, the Lancet was publishing papers related to the bacterial contamination of swimming baths and means to sterilize them, including chlorination.


By the middle of the twentieth century compounds consisting of chlorine with cyanuric acid became available for swimming pool use.  Like earlier forms of chlorine sterilizers, these materials function as a source of hypochlorous acid, which is the active sanitizing agent.


When used correctly, the combination of dichloroisocyanurates and cyanuric acid stabilizers provides long lasting chlorine, good solubility, ease of application, and will not affect the pH of the water.


Today the typical residential pool owner uses a combination of chlorine-containing isocyanurates pressed into slowly dissolving tablets for steady, long term chlorination, and calcium hypochlorides for periodic "shock treatments."


The United States Public Health Service first published a model ordinance governing the construction, sterilization, and use of public pools in 1961. 


The first fissures in the summer love affair of chlorine and swimming came in 1974 when chemists first discovered that halogens could react with organic material in drinking water to create chloroform and other trihalomethanes.


Should the average swimmer be concerned about chloroform exposure? 


The EPA has studied the subject and published a number of documents.  The interested reader should consult these.


This Information Posted by:



Kevin Olsen

Instrumentation Specialist

Chemistry and Biochemistry Support Staff

Room 359 Richardson Hall

Montclair State University

Normal Ave

Montclair, NJ, 07043


973-655-7772 (Fax)


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