How John Leal Put Poison In Our Drinking Water–And Saved Us All

Today, we in the US take safe, clean, drinking water for granted. But it wasn’t very long ago that drinking the water in any major city was a pretty good way to die. We can thank a man named John Leal for solving that problem–in the face of public anti-science ignorance and hysteria.


Water treatment plant                                                          Photo from Wiki Commons

In 19th century America, the drinking water was deadly. American cities were literally open sewers. There was no system of waste removal, and everyone emptied their chamber pots into the streets, where the human waste mixed together with the horse manure piled up by the thousands of horse-drawn carts and buggies, along with rotted trash and offal that was casually tossed into the street. As a result of the unsanitary conditions, epidemics of cholera, typhoid fever and other water-borne diseases were rampant, and routinely claimed thousands of lives.

In the 1850’s, the first sewer systems in the US appeared in Chicago and New York City. These piped waste water from houses and apartments to underground pipes that emptied into a nearby body of water (Lake Michigan or the Hudson River). There was an immediate improvement in the city, as the filth, muck and smells disappeared. But the health problems remained: the germ theory of disease did not exist yet, and it was believed that diseases were caused by “miasmas” or “bad air”, and that sickness was the result of breathing in these toxic odors. By confining human waste to the sewers and dumping it away from the city, it was assumed, the cause of disease epidemics would be removed. All it actually did, of course, was contaminate the city’s water source with its own sewage, guaranteeing that cholera and other diseases would run rampant. It wasn’t until the 1870’s that science definitively proved that diseases are caused by germs. As a result, city sewer and water systems were carefully reworked to insure that the sewage would be kept entirely separate from the drinking supply.

But the cholera and typhoid epidemics continued. Removing the sewage contamination had been an enormous step in the right direction, but it was not enough–the sewage was not the only source of contamination. What was really needed, some people began to realize, was a way to kill all the germs in the water before it was used, no matter where the germs had come from. In short, a disinfectant.

It was already known that certain chemicals, such as copper sulfate solution or oxalic acid, killed germs. One of the most effective and readily available of these “disinfectants” was chlorine. In 1894, scientific papers began appearing suggesting that chlorine, in the form of powdered calcium hypochlorite (now known as bleach powder), could be added to drinking water to kill the germs. Experiments were carried out in Hamburg, Germany, and then in Maidstone, England. Then, in 1905, British doctor Alexander Cruickshank was allowed to oversee the installation of a process to add calcium hypochlorite solution to the drinking water in Lincoln, England, to help stop a typhoid epidemic there. It worked, and the water continued to be chlorinated until 1911, when the city switched to a new cleaner water supply.

In the United States, however, these experiments were met with fear and derision. Newspapers railed against “poisonous chemicals in the water”, and every time a proposal was made to add disinfectant to the public drinking water it was opposed loudly and bitterly by throngs of people who feared it would kill them. Even the use of harmless chemicals like alum to clarify the water brought opposition. “We don’t want puckered water!”, protest crowds would chant at city meetings.

In 1899, a medical doctor named John L Leal, who worked as an inspector on the Board of Public Health in Paterson, New Jersey, quit his job with the city and went to work as a sanitary consultant for a privately-owned water company, the Jersey City Water Supply Company. Paterson did not have a sewer system, and its raw waste was being dumped into the Passaic River. The infant mortality rate was over 20%, caused mostly by diarrhea and cholera from contaminated drinking water. The JCWSC had just won a contract to develop a new clean water supply by damming the Rockaway River outside of town.

But when the water from the newly-created Boonton Reservoir was tested, it was found to still contain cholera and typhoid bacteria two or three times a year, particularly after heavy summer rains–enough to infect people who drank it. The city sued, charging that the company had broken the contract by not providing safe clean water, and the judge issued a ruling in March 1908 requiring the water company to either build a sewer system or find “other plans or devices” to remove the bacteria. The company was given only 90 days to comply.

It was then that Dr Leal made a proposal to the company. Instead of building an expensive sewer system that would not solve the problem anyway, he proposed making the reservoir water safe by using a disinfectant to kill the bacteria in it. As a medical doctor, Leal knew that chlorine was extremely effective in killing germs (a fact he confirmed for himself with some experiments at home), and he was familiar with the tests that had been carried out in Germany and England. So he proposed adding a solution of dissolved calcium hypochlorite powder (which today we would call “bleach”) to the city’s water, at a concentration of around 0.3 parts per million, before it was pumped out for distribution. This was enough to kill all the germs, but too low a dosage to cause any human effects. And how would Leal get around the massive hysterical public opposition to the “poisonous water!” that this plan would surely bring? Simple–he wouldn’t tell them.

It was therefore in total secrecy that Leal brought in famed hydraulic engineer George Warren Fuller to design and build a water treatment plant at the reservoir, capable of chlorinating 30-40 million gallons of water per day, at a cost of 14 cents per million gallons. The system was up and running within the judge’s three-month deadline, and on September 26, 1908, chlorinated water began being delivered to the unsuspecting residents of Paterson, NJ.

The city residents did not find out about it until three days later, when the water company and Leal once again appeared before the judge and informed him that they had begun disinfecting the water as part of his order allowing “other plans or devices”. The judge was shocked. “Do you drink this water yourself?” he asked. “Yes,” Leal replied. “Habitually?”  “Yes.” “And you would not hesitate to have your family drink this water?” “I believe,” Leal firmly answered, “that this is the safest water in the world today.” Over the next 38 days, as city residents protested outside, the judge listened to three thousand pages of testimony from experts who had performed tests on the reservoir water, and found it was germ-free, and had no health effect on humans. On May 9, 1910, he ruled that the water company had now met its contractual obligation to provide the city with “pure and wholesome” drinking water.

The effect was immediate. In Paterson, the death rate from typhoid fever fell from 40.6 per 100,000 inhabitants in 1898 to 21.4 per 100,000 in 1908 to 10 per 100,000 in 1910, and almost zero by 1925. By 1914, some 21 million people in cities across the US were drinking chlorinated water, rising to 33 million people in over 1,000 cities by 1918. By 1940, deaths from cholera and typhoid fever had virtually disappeared in the United States. All because of chlorinated water.

Leal unfortunately did not live to see the triumphant success of his ideas.  He died in March 1914, at age 55, of complications from diabetes. But the chlorination process that he pioneered, in the face of public ignorance and hysteria, has saved billions of lives around the world.

4 thoughts on “How John Leal Put Poison In Our Drinking Water–And Saved Us All”

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