Nitrate Contaminates Drinking Water for Millions of Americans, New National Study Finds
Why It Matters
A newly released study reveals that nearly one-fifth of Americans have been relying on drinking water systems with elevated and potentially dangerous levels of nitrate — a finding with direct implications for communities across the Mountain West and Pacific Northwest, including states like Idaho, Wyoming, and Oregon where agriculture is a cornerstone of the economy.
The contamination is largely driven by nitrogen fertilizers and livestock manure runoff, meaning the states that feed the nation may also be shouldering some of the heaviest costs to keep their water safe.
What Happened
The nonprofit Environmental Working Group released a new analysis Thursday examining test data collected by water systems across the country between 2021 and 2023 — the most recent data available.
The report found that water systems serving more than 3 million people exceeded the federal safety limit of 10 milligrams per liter of nitrate over the three-year period. Researchers also found that thousands of water systems serving more than 62 million people reported nitrate levels above 3 milligrams per liter at least once during those years, a level researchers say indicates human-caused contamination.
Anne Schechinger, the organization’s senior director of agriculture and climate research and the report’s author, cautioned that the problem is not limited to small farming towns. “A lot of people have this idea that this issue is just a rural issue for small towns near farms,” Schechinger said. “But we found with this analysis that that is not just the case. Based on how watersheds work, you can live very far from a farm and still be drinking water contaminated with nitrate.”
By the Numbers
- Nearly 1 in 5 Americans relied on drinking water systems with elevated nitrate levels in recent years.
- 3 million-plus people were served by water systems that exceeded the federal legal limit of 10 mg/L.
- 62 million people were served by systems that recorded nitrate at or above 3 mg/L at least once.
- 64% of all water systems recording nitrate at or above the legal limit were concentrated in just five states: California, Texas, Kansas, Nebraska, and Oklahoma.
- Des Moines, Iowa operates one of the largest nitrate removal systems in the world, costing approximately $16,000 per day to run.
Zoom Out
Agricultural states bear a disproportionate share of the burden. Kansas, Nebraska, and Oklahoma — all major farming states — are among the five states accounting for nearly two-thirds of water systems breaching the federal safety threshold. The data, drawn from public records in every state except New Hampshire, paints a picture of a nationwide infrastructure challenge that is growing more expensive to manage.
Smaller rural communities relying on groundwater have been forced to dig deeper wells to find cleaner sources, according to Schechinger. Larger cities face operational costs that strain public budgets. Iowa’s largest water provider last year asked residents to reduce non-essential water use — such as lawn watering, pool filling, and car washing — as its nitrate removal system struggled to keep pace with seasonal spikes.
Some researchers are increasingly calling for the federal safety threshold to be lowered, citing emerging studies that link even low levels of nitrate consumption to cancer and birth defects. Federal law currently limits nitrate levels primarily because of its long-established connection to blue-baby syndrome in infants. Any push to lower that threshold would likely trigger significant regulatory and cost implications for local water providers and the agricultural industry alike. The debate over tighter federal water mandates comes at a time when many conservatives and rural communities are pushing back against expanded government regulation of farming practices.
For context on broader federal budget priorities shaping environmental and infrastructure spending, see coverage of the U.S. Senate GOP budget blueprint, which is laying the groundwork for significant federal resource allocations in the months ahead.
What’s Next
The Environmental Working Group has published an interactive map identifying community water systems with elevated nitrate levels across the country, giving residents a tool to assess local water safety.
Policymakers at the federal and state levels are expected to face growing pressure to address aging water infrastructure and tighten nitrate standards — though any regulatory changes would need to weigh the significant financial burdens placed on local governments, water districts, and agricultural producers. As local governments across the Mountain West grapple with infrastructure funding decisions, the cost of clean water treatment is likely to become an increasingly prominent issue on municipal and state ballots.
Researchers say extreme weather patterns are expected to worsen seasonal nitrate runoff, meaning the financial and public health stakes are only likely to grow in coming years.
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