Flint, Mich., isn't the only American city where the water hasn't been safe to drink, new research suggests.
Almost 8 percent of community water systems are plagued by health-based violations of water quality standards in any given year, the study found. That meant up to a quarter of all Americans were affected.
"Generally, the U.S. has high-quality water," said study author Maura Allaire. "But health-related violations do extend well beyond Flint. When I dug into the data, I saw about 21 million people were receiving water from systems that didn't meet standards in 2015.
"In terms of hot spots in the country, rural communities and rural low-income communities in Oklahoma and Texas are really struggling," said Allaire, an assistant professor of urban planning and public policy at the University of California, Irvine.
"They lack the technical capacity of larger systems, and have small customer bases, which means they can't afford the latest and greatest technologies. And they often have only a part-time technician monitoring their water systems," she explained.