Nearly 100 million Americans exposed to contaminated drinking water

A new study from the Silent Spring Institute reveals a troubling reality: almost one-third of Americans have been exposed to unregulated contaminants in their drinking water. 

These harmful chemicals, not covered by current federal safety rules, could affect people’s health. 

The study also shows that Hispanic and Black communities are more likely to face unsafe levels of these pollutants, often living closer to sources of pollution.

Extent of contaminated water 

The researchers analyzed data from the U.S. Environmental Protection Agency (EPA) collected between 2013 and 2015. The team looked at 4,815 public water systems across the country. 

The study revealed that 27% of these systems – serving about 97 million people – had detectable levels of at least one unregulated chemical.

Public water systems are required by law to test for nearly 100 specific contaminants. These tests ensure that dangerous levels of those substances do not enter our taps. 

However, thousands of other chemicals are not regulated under the Safe Drinking Water Act. These unregulated chemicals can slip into groundwater and surface water, sometimes reaching the water we drink.

“We know there are thousands of other harmful chemicals that are not regulated that make their way into groundwater and surface waters, and some of these chemicals can ultimately end up in drinking water supplies,” explained Laurel Schaider, a senior scientist at the Silent Spring Institute.

Which chemicals are in our water?

Among the harmful substances found in drinking water are:

• 1,4-dioxane: A solvent that is considered a probable human carcinogen. It can also be found in everyday consumer products.
• PFAS (per- and polyfluoroalkyl substances): Chemicals used to make non-stick coatings and water-resistant fabrics. They are linked to various health issues, including cancer and thyroid problems.
• Chlorodifluoromethane (Freon 22): A gas once used in refrigeration and manufacturing products like Teflon.
• 1,1-dichloroethane: A chemical used in making paints, plastics, and pesticides, which is also associated with cancer.

These chemicals are not regularly monitored by water systems, which means their levels could rise without triggering safety actions.

Disproportionate impacts across communities

The study found that communities with higher percentages of Hispanic and Black residents are more likely to have drinking water with these unregulated chemicals. 

These communities often live closer to places that release pollution, such as industrial sites, waste treatment plants, airports, and military areas.

“Our findings show that the percentage of Hispanic and Black residents in a community is a consistent predictor of poorer water quality,” said Aaron Maruzzo, lead author of the study and a scientist at Silent Spring Institute.

This situation cannot be explained by income or socioeconomic status alone. The researchers suggest that systemic issues like racism and the historical practice of redlining – which led to placing industrial facilities near communities of color – contribute to the unequal distribution of pollution and contaminated water.

Contaminated water across the nation 

Past research by Silent Spring Institute has shown that Hispanic residents are more likely to drink water with high nitrate levels, which can lead to health problems like colorectal and bladder cancer. 

Other studies found that community water systems serving majority Hispanic and Black populations often have higher PFAS levels.

The new study is notable because it examines disparities in exposure to PFAS and other unregulated contaminants across all U.S. states, Tribal lands, and territories, offering a comprehensive look at nationwide water quality issues.

The growing PFAS problem

PFAS chemicals are more widespread in drinking water than previously thought. As recent tests reveal, many more people may be affected by these substances than the data from 2013 to 2015 indicated. 

This makes the study’s estimate of 97 million residents likely an undercount, highlighting an even larger problem.

In April 2024, the EPA set new drinking water standards for six PFAS chemicals, marking a step forward. However, the study underscores a larger need for federal action: regulating more harmful contaminants and addressing the disproportionate exposure that communities of color face.

“Ultimately, we need to do a better job at protecting source waters and reducing discharges of pollutants into water bodies that feed into our drinking water supplies,” Schaider emphasized.

Moving toward safer and fairer water quality 

The researchers hope that by making their inventory of unregulated contaminants publicly available, policymakers will be better equipped to create realistic plans for preventing and mitigating water contamination. 

This data can guide efforts to ensure safe drinking water for everyone, especially those most at risk.

The study casts a spotlight on a critical public health issue: the uneven burden of contaminated drinking water on minority communities.

Addressing this challenge involves not only setting stricter regulations for a wider range of chemicals but also tackling the environmental injustices that place these populations at higher risk. 

By improving source water protection and reducing pollution, society can work toward equitable access to safe drinking water for all Americans.

The study is published in the journal Environmental Health Perspectives.

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