How safe is our drinking water? Threats from chemical spills, pathogens, and terrorism.

How Safe Is Our Drinking Water?

How Safe Is Our Drinking Water?

The state of the universe.
Jan. 16 2014 11:39 PM

How Safe Is Our Drinking Water?

Poisoning the enemy is a long-standing military strategy.

Leaking MCHN tanks at Freedom Industries are being off loaded into tanker trucks on January 10, 2014  in Charleston, West Virginia.
Leaking MCHM tanks at Freedom Industries are being off loaded into tanker trucks on Jan. 10, 2014 in Charleston, W.Va.

Photo by Tom Hindman/Getty Images

The area around Charleston, W.Va., has been brought to its knees by contaminated drinking water. Thousands of gallons of an industrial chemical used for treating coal, MCHM, leaked last week from a company’s steel tank, flowed down the bank and into the Elk River, located just a mile upriver from the intake point for the region’s drinking water treatment plant.

Residents quickly noticed the licorice smell and a few hours later were officially warned not to drink or cook, wash, or bathe with the water. A state of emergency was declared in nine counties. Schools, hospitals, restaurants, hotels, and more closed. About 300,000 residents were affected.

We take the quality of our drinking water for granted, and for good reason. More people in the United States have access to safe water than ever before. Yet recent events raise an obvious concern: How safe is our drinking water really?


This question is both timely and timeless, for water providers have constantly defended water sources against contamination. From well before the Romans through today, they have always faced three broad classes of threats.

The first comes from natural contaminants—pathogens we expect to find in water. Despite images of clear, burbling springs and mountain streams, the simple fact is that fresh water is just not very clean. Teeming parasites, viruses, and bacteria live in water. Just a hundred years ago, dying from waterborne typhoid or cholera was commonplace in the United States, and deadly epidemics still break out in some parts of the world today. The addition of chlorine to water supplies a century ago largely eliminated these scourges. We have since become very good at eliminating biological pathogens with chlorination, ozonation, ultraviolet radiation, and filtration as redundant lines of defense. Nonetheless, vigilance remains necessary. Just two decades ago, a treatment plant piped contaminated water to Milwaukee residents, sickening one-quarter of the city’s population. Sixty-nine people died.  

Intentional attack presents the second class of threat. While Sept. 11 focused immediate attention on drinking water, these are hardly new concerns. Poisoning the enemy is a long-standing military strategy. When Solon of Athens laid siege to Cirrha circa 600 B.C., he ordered that poisonous hellebore roots be placed in the local water supply, making the Cirrhaeans violently sick. In 1941, concerned over domestic attacks from Nazi or Japanese agents, J. Edgar Hoover warned about the vulnerability of water supply facilities “due to the strategic position they occupy in keeping the wheels of industry turning and in preserving the health and morale of the American populace.”

There have not been any successful major attacks on American water supplies, but the threat and fear remain because our water supplies cannot be fully protected. We could erect more fences, higher fences, locks, security cameras, and hire more guards—and we have—but with more than 75,000 dams and reservoirs, more than 160,000 drinking water facilities, mostly owned and operated by local government and private parties, 2 million miles of pipe and millions more access points, these measures will never make us completely safe. Our water systems present an impossibly big target to protect from intentional acts or accidents.

The good news is that poisoning a water system is hard to do. Putting a few drops of cyanide in someone’s glass will lead to a gruesome death. Putting a few drops, or even a few barrels, in a reservoir is pointless. Reservoirs generally hold anywhere from 3 million to 30 million gallons of water. Even assuming one could back several trucks up to the reservoir and dump their loads without being detected, one would still need to get huge quantities of the poison in the first place. The Department of Homeland Security keeps track of biological and chemical agents that might be used by terrorists, and these substances are not easy to come by in large quantities.