WHEN RESIDENTS IN FLINT, MICHIGAN, learned that the city's water pipes were leaching lead into their drinking water, most people figured it had to do with the less-than-pristine state of the Flint River, which had been used as a repository for industrial waste since lumber mills first appeared on its banks in the 1830s. 

But as Marc Edwards, an engineering professor at Virginia Tech, began investigating reports of lead in Flint's water in the spring of 2015, he came to suspect that the crisis had been set in motion by something much more innocuous: road salt. It's used throughout much of the United States in the winter to boost traffic safety—and that means it threatens not just Flint but communities across the country as well. 

In April 2014, officials appointed by the state of Michigan to reduce Flint's budget deficit switched the city's water supply from the Detroit River to the Flint River to save money. Meanwhile, the water utility—in a move that subsequent lawsuits charged was criminal—failed to apply anticorrosion agents to the city's water supply. Road salt that had washed into the Flint River began to eat away at lead service pipes, which were soon carrying lead particles to faucets all over Flint. The result was a massive public health emergency, one that state officials concealed for a year and a half, until the cover-up was revealed and the story dominated national news. 

The full impacts of the Flint crisis are still being determined. A working paper published a year after the lead contamination was revealed reported that the city's fertility rate had dropped by 12 percent, while rates of miscarriages and stillbirths had risen by 58 percent. Some 9,000 children in Flint were exposed to lead, a potent neurotoxin that affects brain development, kidney function, and the immune system even when ingested in minute quantities. High-quality nutrition, health care, and education mitigate those effects, but in a city like Flint, where 30 percent of households make less than $20,000 a year, access to those isn't easy.

"For at least 18 months, I had been poisoning myself and my daughter," says Gina Luster, an organizer with a group called Flint Rising. Both Luster and her daughter were badly sickened by lead poisoning. Luster lost weight as well as some of her hair and teeth, and her daughter developed a severe vitamin D deficiency. Luster had to quit her job because of the cascade of illness and disease. "My bones were just so brittle. They ached so much. I felt like I was 95 years old." 

The Flint water crisis is a reminder of how hard it is to keep even a blatant hazard out of the environment if that hazard is useful to somebody. When U.S. cities began to construct municipal water systems in the late 19th century, some used iron or wood pipes. Others used pipes made of lead—they lasted longer, and it was easier to bend them around obstacles underground. But in the 1920s, after several brutal episodes of lead poisoning, many cities banned lead pipes.

Those bans lasted only a few decades. The Lead Industries Association wooed plumbers' organizations, local water boards, and federal agencies. And soon lead was once again commonly used, just in time for one of the largest construction booms in U.S. history. In cities like Chicago, new buildings had to use lead pipes in order to connect to the municipal water system.

A nationwide ban on installing new lead pipes was finally instituted with the Safe Drinking Water Act Amendments of 1986. But that didn't address the pipes that were already in the ground, which were considered too expensive to replace. 

Instead, cities and utilities monitor the water supply and apply anticorrosion treatment when lead levels get too high, while the EPA provides oversight. This system has proved imperfect. In June 2016, a Guardian investigation found that at least 33 cities in the United States—including Philadelphia, Chicago, Boston, and Buffalo—were using the same deceptive water-testing methods that Michigan officials used to conceal dangerous levels of lead in Flint.

The only truly effective solution, says Mona Hanna-Attisha, a pediatrician whose research helped reveal the Flint cover-up, would be to remove lead from the environment before it ever reaches children. "We need to proactively check people's homes and their paint and their soil and their dust and their water before a child is exposed. It would save our nation $80 billion a year if we actually did this primary prevention—if we dug up the pipes, if we fixed these homes." 

Edwards is working on an EPA-funded plan that he describes as "one of the largest citizen-science engineering projects in human history." Organizing citizens to test their own water carries risks, he says, but the risk of lead water pipes corroding is going to increase as sea level rise brings more saltwater into coastal water systems. Community science may be the only way to restore trust in a system that, even if it works most of the time, causes an incredible amount of damage when it fails. 

"The simple answer is there's no easy way to know if your city is being honest with you," Edwards says. "That's what we have to do. We have to restore trust when it's justified and expose corruption when it's not." 

This article appeared in the July/August 2018 edition with the headline "Don't Trust—And Verify."