EWG Investigation: In California’s Majority-Latino Communities, 5.25 Million Drink Tap Water With Nitrate Above Federal Limit

Contamination Is Worst in San Joaquin Valley

WASHINGTON – In California’s majority-Latino communities, 5.25 million people drink tap water contaminated with nitrate at levels at or above the federal limit, according to an Environmental Working Group analysis of state and federal data.

Nitrate contamination is widespread throughout California’s drinking water supplies, but EWG’s analysis found that as nitrate levels rise, the likelihood that a community is majority-Latino also goes up – especially in the eight-county San Joaquin Valley, the nation’s leading agricultural region.

“The more nitrate that contaminates a California tap water system, the more likely it is that the system is located in a majority-Latino census block group, particularly in the San Joaquin Valley,” said Anne Schechinger, EWG senior economic analyst and author of the report. “Because the vast majority of the Valley’s essential farmworkers are also Latino, this means that in the nation’s food basket, many people are drinking water contaminated by the very farms that employ them.”

Nitrate is a potentially toxic chemical that primarily enters drinking water supplies from farm runoff polluted with fertilizer and animal manure. The legal limit for nitrate in tap water is 10 milligrams per liter, or mg/L, but recent studies have found that drinking tap water with nitrate at half the legal limit – 5 mg/L – or even less can increase the risk of cancer and other diseases.

For its analysis, EWG compared demographic information, by census block groups, from the 2018 American Community Survey with nitrate tests from the public water systems that serve the communities located in those block groups. Tests were conducted by the utilities, as required under the Safe Drinking Water Act, between 2003 and 2017.

California Contamination

Utility tests detected elevated levels of nitrate in the finished water of hundreds of communities located in census block groups where the population is 50 percent Latino or higher:

  • 140 systems serving 5.25 million people tested at or above 10 mg/L.
  • 318 systems serving 8.1 million people tested at or above 5 mg/L.
  • 415 majority-Latino community water systems serving more than 9 million people tested at or above 3 mg/L, the level the Environmental Protection Agency says indicates that contamination may be getting worse.

Thirty-five percent of all California communities with nitrate levels of 3 mg/L are majority-Latino. That went up to 38 percent for communities that tested at or above 5 mg/L, and 42 percent at or above 10 mg/L.

San Joaquin Valley Contamination

In the Valley, elevated nitrate was also found in numerous communities that were in majority-Latino census block groups:

  • 69 systems serving close to 1.5 million people tested at or above the federal limit of 10 mg/L.
  • 157 systems serving 2.2 million people tested at or above 5 mg/L.
  • 199 majority-Latino systems, serving almost 2.3 million people, tested at or above 3 mg/L.

Fifty percent of communities with nitrate levels of 3 mg/L or more in the Valley are majority-Latino. That goes up to 53 percent of communities that tested at or above 5 mg/L, and 56 percent that tested at or above 10 mg/L.

Of all majority-Latino communities in the Valley with elevated nitrate, 65 percent – 130 communities serving almost 956,000 people – had contamination that got worse between 2003 and 2017.

“Farmworkers and their family members often live in communities that lack adequate infrastructure and, as this report shows, are poisoned by agricultural chemicals in their water supply,” said Bruce Goldstein, president of Farmworker Justice, a nonprofit that advocates for migrant and seasonal farmworkers. “Farmworkers confront occupational hazards from pesticide exposure, Covid-19 and wildfires, as well as low wages and labor abuses.”

“As essential workers in our food system and as human beings contributing to our communities, farmworkers and their children should not have to drink water polluted with farm chemicals,” Goldstein added.

Most of the majority-Latino communities struggling with nitrate are also low-income, with a 2018 average household income of about $49,000 across census block groups, less than half the state’s average income of about $101,000.

Cleaning up California’s nitrate-polluted tap water will require tougher farm regulations and a lot of money. In 2019, the state established the Safe and Affordable Drinking Water Fund, which was intended to provide $130 million a year for the next decade to communities to help rebuild or improve drinking water infrastructure. But the pandemic-triggered economic crisis has put the money on hold.

“California needs real regulations on farm pollution and dedicated funding for water systems that won’t disappear in an economic downturn,” EWG’s Schechinger said.


The Environmental Working Group is a nonprofit, non-partisan organization that empowers people to live healthier lives in a healthier environment. Through research, advocacy and unique education tools, EWG drives consumer choice and civic action. Visit www.ewg.org for more information.

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