Study Finds 20% of Americans Have Unsafe Drinking Water

Potentially unsafe drinking water remains a persistent problem in the United States despite decades of federal efforts and roughly $2 trillion in spending since the 1974 Safe Drinking Water Act, according to a recent National Bureau of Economic Research working paper.

The study found that drinking water for 10 to 20 percent of Americans violates safety standards, even as overall pollution levels have declined substantially in recent decades.

The Safe Drinking Water Act, passed in 1974, is a federal law governing public drinking water in the U.S. It authorizes the Environmental Protection Agency to set minimum health-based standards for tap water and requires public water systems to comply with them.

A related financing program, the Drinking Water State Revolving Fund, was created under 1996 amendments to the law and provides low-interest loans and other assistance for drinking-water infrastructure projects, including treatment upgrades, pipe repairs and improvements to water sources.

Why It Matters

The paper noted that U.S. industry uses more than 42,000 chemicals, while the Safe Drinking Water Act regulates only 90. It also cites Centers for Disease Control and Prevention (CDC) estimates that drinking-water pathogens cause 7 million illnesses and 600,000 emergency department visits each year.

Its authors say they obtained 266 million readings covering 1,250 pollutants across multiple decades from 48 states, using the Freedom of Information Act and related public records requests. They also linked pollution data to administrative Medicare records to study health outcomes among older Americans.

Unsafe Water Persists Despite Decades of Federal Spending

The study's first main finding showed substantial progress in U.S. drinking water quality, though not enough to fully eliminate safety violations.

The authors reported that the share of readings exceeding current health standards fell by about half between 2003 and 2019. However, the study also found that pollutants not subject to regulation declined more slowly, suggesting that progress has potentially been stronger for contaminants covered by existing standards than for those outside them.

Progress Has Not Reached All Communities Equally

The burden of pollution is not evenly distributed, the research suggested. The paper found that low-income areas have higher levels of drinking water pollution. It also reported that Black and Hispanic communities show "more complex patterns," rather than a single uniform disparity across all measures.

Water System Loans Tied to Lower Mortality Among Older Americans

Another focus of the study was whether federal support through the Safe Drinking Water Act has reduced pollution. The authors examined loans provided to water systems under the law and found that those loans reduce pollution. At the estimated average cost-effectiveness, they wrote that such loans could eliminate pollution that exceeds health standards for $46 per person annually.

The study also connected those loans to health outcomes. Using Medicare data, the authors found that Safe Drinking Water Act loans reduce mortality rates among older Americans. They say it indicates significant benefits from the financing program.

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This story was originally published June 19, 2026 at 1:32 PM.