If you think Flint, Mich., is the only place in the United States threatened by lead-contaminated water, think again. The beleaguered city continues to grapple with the fallout of a drinking-water crisis that exposed its residents — including 9,000 children 6 and younger — to a toxic substance that can cause learning disabilities, behavioral problems and other serious health issues.

But while Flint might be an extreme example, a report released Tuesday by the Natural Resources Defense Council details how many other communities around the country are failing to adequately ensure that their water supplies remain free of lead. The report, which analyzed data from the Environmental Protection Agency, found that more than 18 million Americans are served by 5,363 water systems that in 2015 violated the federal rules governing lead testing. READ MORE