10 Environmental Engineers Who Protected the Planet

When you sit for the FE Environmental exam, you will face questions on water treatment, wastewater design, hydraulics, environmental regulations, and risk assessment. The formulas and methods behind those questions did not materialize out of thin air. They were developed by real people who confronted epidemics, pollution crises, and infrastructure failures—often with incomplete data and enormous stakes.

Knowing the people behind the equations does something that a formula sheet alone cannot: it gives you context. When you understand why Manning derived his equation, or what problem Abel Wolman was trying to solve with chlorination, the formulas stop being abstract and start making sense. You remember when to use them, what assumptions they carry, and where they break down.

These are 10 engineers and scientists whose work defines the field of environmental engineering—and whose contributions still appear, by name, on the exam you are studying for right now.

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1. Abel Wolman (1892–1989) — The Man Who Made Drinking Water Safe

Before Abel Wolman, chlorinating a city’s water supply was more art than science. Operators added bleach or chlorine in rough quantities, sometimes disinfecting effectively, sometimes not, and occasionally poisoning people in the process. There was no systematic method for determining how much chlorine a water supply actually needed.

Wolman, a young engineer at the Maryland Department of Health, changed that in 1919. Working with chemist Linn Enslow, he developed a scientific formula for chlorine dosing based on measurable water quality parameters—pH, temperature, organic content, and contact time. Their method allowed operators to calculate precise chlorine doses that would reliably kill pathogens without creating dangerous residuals. It was the first time water disinfection could be applied consistently at scale.

The impact was staggering. Within a decade, waterborne disease rates in American cities plummeted. Typhoid fever, which had killed thousands every year, was virtually eliminated as a public health threat in communities that adopted Wolman’s methods. Over the following decades, Wolman became one of the most influential public health engineers in history, advising governments on six continents and serving as a consultant into his 90s. The American Public Health Association later called the chlorination of drinking water “probably the most significant public health advance of the twentieth century.”

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2. Ellen Swallow Richards (1842–1911) — The First Environmental Scientist

Ellen Swallow Richards was the first woman admitted to the Massachusetts Institute of Technology—in 1871, when the institution was barely a decade old. She earned a bachelor’s degree in chemistry, then stayed at MIT as an unpaid instructor for years because the university would not grant her a doctoral degree on account of her gender. She turned that position into a career that essentially invented the field we now call environmental science.

In the 1880s, Richards conducted the first comprehensive survey of water quality in the United States, analyzing over 40,000 water samples from across Massachusetts. She developed new techniques for measuring chlorine, dissolved oxygen, and hardness in water, and her data directly led to the first state water quality standards in the country. Her laboratory methods for detecting contamination became the basis for public water testing programs nationwide.

Richards also pioneered what she called “oekology”—the study of how human environments affect health—decades before the modern environmental movement existed. She wrote extensively on air quality, food purity, and industrial pollution, always grounding her advocacy in rigorous chemical analysis. Her insistence that environmental decisions be based on measured data, not assumptions, set a standard that the field still follows.

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3. John Snow (1813–1858) — The Detective Who Traced a Killer to Its Source

In August 1854, a devastating cholera outbreak struck the Soho district of London, killing over 600 people in just two weeks. The prevailing medical theory blamed “miasma”—bad air rising from sewers and rotting waste. John Snow, a physician who had been studying cholera patterns for years, was convinced the theory was wrong. He believed the disease was transmitted through contaminated water, and he set out to prove it.

Snow meticulously mapped every cholera death in the neighborhood, recording addresses, interviewing survivors, and cross-referencing the data with the locations of public water pumps. His map revealed a striking pattern: cases clustered overwhelmingly around a single pump on Broad Street. He also found telling exceptions—a brewery near the pump had almost no cases (its workers drank beer, not water), and a distant workhouse with its own well had a high death rate because it drew water from a contaminated source near Broad Street.

Snow presented his evidence to local authorities, who agreed to remove the handle of the Broad Street pump. The outbreak subsided. Snow’s investigation became one of the founding cases of epidemiology and established the critical link between water supply and disease transmission—a link that would drive every major advance in water treatment engineering for the next 170 years.

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4. George Warren Fuller (1868–1934) — The Engineer Who Proved Filtration Works

By the late 1800s, American cities were growing faster than their water infrastructure could keep up. Waterborne disease epidemics were routine—typhoid, cholera, and dysentery killed thousands every year. European cities had begun experimenting with slow sand filtration, but the method was expensive and required enormous land areas. American water engineers needed something faster.

George Warren Fuller provided the answer. In 1897, working in Louisville, Kentucky, he conducted the first large-scale, scientifically rigorous study of rapid sand filtration for municipal water treatment. His experiments systematically tested different sand sizes, filtration rates, coagulant doses, and backwash procedures, producing data that could be used to design full-scale treatment plants. The Louisville experiments proved that rapid filtration—combined with chemical coagulation using alum—could produce water quality comparable to slow sand filtration at a fraction of the cost and footprint.

Fuller’s work transformed American water treatment. Within two decades, hundreds of cities had built rapid sand filtration plants based on his design principles. He went on to consult on water and wastewater projects across the country, earning a reputation as the most important water treatment engineer of his generation. The design parameters he established—filtration rates, media specifications, backwash criteria—remain the basis for conventional water treatment plant design today.

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5. Rachel Carson (1907–1964) — The Writer Who Launched Environmental Regulation

Rachel Carson was not an engineer—she was a marine biologist and writer. But no single individual did more to create the regulatory framework that environmental engineers work within today. Her 1962 book Silent Spring documented the devastating ecological effects of DDT and other synthetic pesticides, tracing their path from agricultural fields through waterways, soil, and food chains to wildlife populations and human health.

The chemical industry attacked Carson viciously, dismissing her as “hysterical” and scientifically illiterate. She was neither. Silent Spring was meticulously researched, drawing on peer-reviewed studies, government data, and field observations. Carson did not call for banning all pesticides—she called for informed, science-based regulation that weighed ecological risks against economic benefits. Her argument was fundamentally an engineering one: that the consequences of introducing persistent chemicals into the environment must be understood before, not after, widespread deployment.

The public response to Silent Spring led directly to the creation of the Environmental Protection Agency in 1970, the passage of the Clean Air Act, the Clean Water Act, the Safe Drinking Water Act, and the Toxic Substances Control Act—the entire regulatory architecture that defines modern environmental engineering practice. Every permit, every discharge limit, every remediation project, and every risk assessment that environmental engineers perform today exists because Carson demonstrated that unregulated chemical release had consequences.

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6. W. Wesley Eckenfelder (1926–2012) — The Master of Biological Wastewater Treatment

For most of the twentieth century, designing a wastewater treatment plant was part science, part guesswork. Engineers knew that biological processes could break down organic waste, but the design methods were empirical and inconsistent. A plant that worked in one city might fail in another, and nobody could reliably predict why. W. Wesley Eckenfelder spent his career fixing that problem.

Eckenfelder developed rational design methods for biological treatment systems—activated sludge, trickling filters, aerated lagoons, and anaerobic digesters. He created mathematical models that linked organic loading rates, microbial growth kinetics, oxygen transfer rates, and sludge production to measurable design parameters. His textbook Industrial Water Pollution Control, first published in 1966, became the standard reference for wastewater engineers worldwide and went through multiple editions over four decades.

What set Eckenfelder apart was his focus on industrial wastewater—the far more complex and variable counterpart to municipal sewage. Industrial effluents contain everything from heavy metals and solvents to high-strength organic wastes, and each requires a tailored treatment approach. Eckenfelder developed design frameworks flexible enough to handle this variability, teaching generations of engineers how to characterize a waste stream, select appropriate treatment processes, and size equipment for reliable performance.

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7. G. Clifford White (1914–1999) — The Authority on Chlorination Practice

If Abel Wolman made water chlorination scientifically possible, G. Clifford White made it reliably practical. White spent five decades studying every aspect of chlorine disinfection—chemistry, equipment, operations, safety, and monitoring—and compiled his findings into Handbook of Chlorination and Alternative Disinfectants, first published in 1972. The book became the definitive reference for water treatment operators and engineers worldwide, running to over 1,500 pages in its later editions.

White’s contribution went far beyond compiling existing knowledge. He conducted original research on chlorine contact time and its relationship to pathogen inactivation, work that directly informed the development of the CT (concentration × time) concept now used in every water treatment plant in the United States. He also studied the formation of disinfection byproducts, the effectiveness of alternative disinfectants like chloramine and chlorine dioxide, and the design of chlorine feed and monitoring systems.

His practical focus made him invaluable. White understood that a disinfection system was only as good as its day-to-day operation, and he wrote extensively about troubleshooting, safety protocols, and the real-world challenges that operators face. His work bridged the gap between laboratory science and field practice in a way that few other researchers matched.

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8. Daniel Okun (1917–2007) — The Champion of Water Reuse

Daniel Okun saw something in the mid-twentieth century that most water engineers refused to consider: the world was going to run out of fresh water unless it learned to reuse what it had. At a time when the idea of reclaiming treated wastewater for any purpose struck most people as unthinkable, Okun built a career arguing that water reuse was not just feasible but essential.

As a professor at the University of North Carolina for over five decades, Okun became one of the most respected voices in international water supply engineering. He advised the World Health Organization, the World Bank, and governments across the developing world on water infrastructure planning. His central argument was deceptively simple: dual distribution systems—one supplying potable water, one supplying reclaimed water for irrigation, industrial cooling, and fire protection—could dramatically reduce demand on freshwater sources while maintaining public health.

Okun also championed regionalization of water systems, arguing that small, fragmented utilities could not afford the treatment technology and professional staff needed to produce safe water consistently. His advocacy for consolidated regional systems influenced water infrastructure planning across the United States and in developing nations where the stakes were even higher. Today, as water scarcity intensifies worldwide, Okun’s vision of integrated water reuse is becoming standard practice.

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9. Robert Manning (1816–1897) — The Equation That Governs Every Open Channel

Robert Manning was an Irish engineer who spent most of his career working on drainage and arterial navigation projects for the Irish Office of Public Works. He was not a professor, not a researcher by training, and not particularly famous during his own lifetime. But his name appears in virtually every hydraulics textbook in the world, and every environmental engineer who has ever designed a storm sewer, sized a drainage channel, or analyzed overland flow has used his equation.

In 1889, Manning presented his open channel flow formula to the Institution of Civil Engineers of Ireland. The equation relates flow velocity to channel slope, hydraulic radius, and surface roughness through a single, elegantly simple relationship. What made Manning’s formula succeed where earlier equations (by Chezy, Kutter, and others) had not was its combination of accuracy and usability. It required only one empirical coefficient—the roughness coefficient n—and produced reliable results across a wide range of channel types and flow conditions.

Manning himself was characteristically modest about his contribution, noting that the formula was an empirical fit to experimental data rather than a derivation from first principles. But empirical or not, the equation works. It has been validated against over a century of field measurements, and it remains the standard method for open channel flow calculations in the United States, used in everything from municipal stormwater design to floodplain analysis to environmental permitting.

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10. Allen Hazen (1869–1930) — The Engineer Behind Sedimentation and Pipe Flow

Allen Hazen was one of those rare engineers whose work touched nearly every corner of his discipline. A contemporary of George Warren Fuller, Hazen made foundational contributions to both water treatment and hydraulic engineering—and his name is attached to equations and concepts that environmental engineers use daily.

His most enduring contribution to water treatment is Hazen’s theory of sedimentation. In 1904, Hazen published a systematic analysis of how particles settle in rectangular sedimentation basins, demonstrating that removal efficiency depends on the ratio of flow rate to basin surface area—the overflow rate—rather than on detention time alone. This insight revolutionized sedimentation basin design and remains the basis for sizing clarifiers in both water and wastewater treatment plants.

Hazen is also co-credited (with Gardner Stewart Williams) for the Hazen–Williams equation, one of the most widely used formulas for calculating head loss in pressurized pipe flow. The equation provides a simpler alternative to the Darcy–Weisbach equation for turbulent flow in water pipes, using a single roughness coefficient (the C-value) that accounts for pipe material and age. Nearly every water distribution system in the United States has been designed or analyzed using the Hazen–Williams equation, and it appears in the FE Reference Handbook alongside Darcy–Weisbach as a standard tool for pipe flow calculations.

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What These Pioneers Have in Common

These 10 individuals worked across two centuries, on different continents, and in specialties ranging from microbiology to hydraulics to public policy. But they share several qualities worth noting as you prepare for your own engineering career:

• They solved problems with data. Snow mapped cholera deaths. Richards analyzed 40,000 water samples. Fuller ran systematic filtration experiments. Wolman derived dosing formulas from measurable parameters. Environmental engineering has always been a discipline where evidence wins—and the FE exam tests whether you can work with data, not just memorize answers.
• They thought about systems, not just components. Okun saw water supply and wastewater as parts of a single cycle. Carson traced pesticides through entire ecosystems. Eckenfelder connected microbial kinetics to plant-scale performance. The FE exam rewards this systems thinking—understanding how treatment processes, regulations, and natural systems interact.
• They prioritized public health. At its core, environmental engineering exists to protect people. Every equation you study for the FE exam—from CT values to BOD kinetics to Manning’s formula—was developed to make water safer, air cleaner, or communities more resilient. That mission has not changed.
• They built on each other’s work. Snow’s epidemiology led to Fuller’s filtration, which led to Wolman’s chlorination, which led to White’s CT concept. Environmental engineering is cumulative, and the FE exam tests your ability to connect the pieces.

Your Turn

You are studying the same water treatment principles, the same hydraulic equations, the same biological processes, and the same regulatory frameworks that these pioneers developed to protect public health and the environment. The formulas in your FE Reference Handbook are not abstract—they are the distilled insights of people who stopped cholera epidemics, cleaned polluted rivers, and built the infrastructure that makes modern life possible.

Passing the FE Environmental exam is your first professional milestone in a field that has always attracted people who want their work to matter. These 10 engineers and scientists show where that foundation can take you.

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