Tap water contamination underreported in U.S.

If you live in the United States, there is a nearly 1-in-4 chance your tap water is either unsafe to drink or has not been properly monitored for contaminants in accordance with federal law, a new study has found.

In 2015, nearly 77 million Americans lived in places where the water systems were in some violation of safety regulations, including the 1974 Safe Drinking Water Act, according to the report released on Tuesday from the Natural Resources Defense Council, a New York-based environmental advocacy group.

It’s not only that some tap water has high levels of lead, nitrates, arsenic or other pollutants, said Mae Wu, a senior attorney with the council’s health program. It is that too often, a lack of reporting means residents cannot be sure whether their drinking water is contaminated or not.

The issue is not new; tap water safety violations across the United States have been reported again and again and again. The new study is an attempt to tell the big-picture story, Ms. Wu said, as a backdrop to the piecemeal reports coming out of towns and cities across the country.

These include the story of a sinkhole outside Tampa, Fla., which opened up in September, leaking contaminated water and endangering a major aquifer; Florida’s Department of Environmental Protection took weeks to notify nearby residents.

Or Jim Hogg County, Texas, where thousands of people were exposed to high levels of arsenic in their drinking water for years, according to a report last year from the Environmental Integrity Project, a nonprofit group based in Washington.

The report, which relied on data collected by the EPA itself, includes a list of 12 states with the most water safety violations based on population; it is topped by Texas, Florida, Pennsylvania and New Jersey.