In earlier outbreaks, the authorities had simply warned people to boil their water before drinking it. But of course there was no way to boil an entire reservoir. But a new idea for fighting the bacteria had emerged: killing the microbes not with heat, but with poison. A Cambridge pathologist named G. Sims Woodhead treated the water with calcium hypochlorite, the potentially lethal chemical that is better known as chlorine, also known at the time as “chloride of lime.” His temporary experiment marked the beginning of a practice that would eventually spread around the world, and would prove to be one of the most significant public health innovations of the twentieth century: chlorinated drinking water.
But Woodhead’s innovation was an emergency measure, instituted temporarily to stop a deadly outbreak. The idea of chlorinating water by default would take another 10 years to develop, thanks to the bold — some might even say reckless — actions of a New Jersey doctor named John Leal.
[...]
In almost complete secrecy, without any permission from government authorities (and no notice to the general public), Leal decided to add chlorine to the Jersey City reservoirs. With the help of engineer George Warren Fuller, Leal built and installed a “chloride of lime feed facility” at the Boonton Reservoir outside Jersey City. It was a staggering risk, given the popular opposition to chemical filtering at the time. But the court rulings had severely limited his timeline, and he knew that lab tests would be meaningless to a lay audience. “Leal did not have time for a pilot study. He certainly did not have time to build a demonstration-scale facility to test the new technology,” Michael J. McGuire wrote in his account, “The Chlorine Revolution.” “If the chlorine of lime feed system lost control of the amount of chemical being fed and a slug of high chlorine residual was delivered to Jersey City, Leal knew that would define the failure of the process.”
From the article:
[...]