How Chlorine got into our Drinking Water: Exploring the Adjacent Possible

One morning, in 1908, without any governmental approvals or public notice, a doctor and an engineer executed the first mass chlorination of a city’s water supply in history. If I had to analogize innovation, it would be someone throwing a stone into a pond, creating ripples that extend outward until the surface eventually calms again. In this analogy, the initial splash might be a technology, which has visible effects on the surrounding environment (ripples) that eventually dissipate as the innovation becomes a norm. This, however, is a shortsighted view of innovation. A far less emphasized aspect of innovation is what happens when a new development in one field triggers an unforeseen advancement in a seemingly unrelated field or industry — the long view.

photo cred: Peer Insight Ventures

In the long view version of our stone-throwing analogy, the ripples in the pond that received the stone manage to create ripples in a separate pond nearby. When applied to innovation efforts, this second-order thinking can help illuminate the potential downstream impacts on peripheral or unrelated industries. This thinking offers access to a realm of opportunity that not only satisfies a creator’s itch but also makes good business sense. The story of how chlorine became the means of safe water supply systems illustrates the power of this long view.

Working with an engineer named George Warren Fuller, Dr. John Leal orchestrated the introduction of “chloride of lime” (chlorine) into the Jersey City reservoirs in secrecy. It was Leal’s exploration into the adjacent possible — domains outside the field in which an innovation was introduced — that transformed the American water system. Specifically, he combined existing inventions and capabilities, like new methods for tracking and counting bacterial colonies, with a unique awareness that chlorine could disinfect water without harming human consumers. While chlorine had been used widely as a disinfectant for homes and communities suffering typhoid and cholera outbreaks, the idea of putting chlorine into water was opposed by most doctors and public health authorities. As a result, nobody anticipated these previous advancements coming together in this way.

Within a few years of Leal’s 1908 experiment on the Jersey City water system, the evidence of the water system’s benefits were indisputable: By 1930, once similar systems had been put in place across the country, there was a 43 percent reduction in total mortality in the average American city. (Thanks to the extensive data on rates of disease and mortality that existed between 1900 and 1930, the period when chlorination systems were implemented across the U.S., and because chlorination systems were installed at different times, it has been possible to get an accurate measure of how chlorine impacted public health¹).

As Leal’s story illustrates, taking a long view on innovation can change the trajectory of societies. More practically, it’s also necessary to explore what else could be possible in an adjacent field or industry because of new products or services. It’s something we’re doing every day at Peer Insight.


¹Johnson, Steven. How We Got to Now: Six Innovations That Made the Modern World. New York: Riverhead Books, 2014.

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