A new Environmental Working Group analysis finds 62 million Americans drank water with elevated nitrate levels between 2021 and 2023, driven largely by agricultural runoff — while the EPA's legal limit hasn't been updated since 1962.
Roughly 62 million Americans drank water contaminated with elevated levels of agricultural nitrates between 2021 and 2023, according to a sweeping new analysis from the Environmental Working Group. The pollution stretches from rural farming counties to major metros including Los Angeles, Phoenix and Philadelphia, and the federal limit meant to protect against it hasn't been updated since the Kennedy administration.
Who profits, who pays
The economics of American agriculture are structured to encourage exactly the inputs that produce nitrate runoff. Federal farm subsidies and the Crop Insurance Program incentivize corn, the most fertilizer-intensive crop grown in the U.S., much of it destined for livestock feed and ethanol rather than direct human consumption.
Treatment costs, meanwhile, fall on water utilities and ratepayers. Small systems serving 3,300 people or fewer make up four out of five of the systems with elevated nitrate, and they have the fewest customers across whom to spread the price of removal technology. The polluter and the payer are not the same party.
The House is expected to vote on a Farm Bill that includes a nearly $1 billion cut to the Environmental Quality Incentives Program, the federal initiative that helps farmers install cover crops, buffer strips and other measures shown to reduce nitrate loss. Anne Weir Schechinger, the EWG report's author, noted that EQIP funding supports conservation practices designed to reduce nitrate contamination in drinking water. Cutting it shifts more cost to utilities and ratepayers downstream.
The EWG analysis estimates the annual U.S. cost of treating cancers attributable to nitrate exposure at between $250 million and $1.5 billion. Minnesota researchers calculated direct medical and quality-of-life costs from nitrate-linked conditions at $745 million per year in that state alone. None of those bills land on the operations producing the pollution.
What the EWG analysis found
The first-of-its-kind national review identified 6,114 community water systems with nitrate readings at or above 3 milligrams per liter, the level state and federal regulators treat as a marker of human-caused contamination. That works out to roughly 18 percent of the U.S. population, or about one in five people.
Of those, 3,201 systems serving 38 million people tested at or above 5 mg/L, the threshold where peer-reviewed research has documented elevated cancer risk. Another 606 systems, serving more than 3 million people, exceeded the legal limit of 10 mg/L at least once during the three-year window.
Seventy water systems tested at twice the legal limit. Twenty-one tested at three times the limit or higher. Garden City, Kansas, serving more than 35,000 residents, recorded a maximum reading of 37 mg/L.
The conventional framing treats nitrate contamination as a rural problem, isolated to small towns surrounded by cornfields. The data tells a different story. Six community water systems serving more than a million people each tested above the threshold regulators use to flag human-caused contamination, meaning the pollution travels through aquifers and rivers far beyond the farms that produce it.
A 1962 standard meeting 2026 science
The EPA's maximum contaminant level of 10 mg/L traces back to a 1962 U.S. Public Health Service recommendation. Its purpose was narrow: prevent blue baby syndrome, a condition that starves infants of oxygen when they ingest too much nitrate.
Decades of research have since linked far lower concentrations to colorectal and other cancers, thyroid disease, low birth weight, preterm birth, and neural tube defects including spina bifida. The EWG report references a peer-reviewed meta-analysis that pegged the health-protective level at 0.14 mg/L, roughly seventy times stricter than the federal standard.
The agency has not moved. A review process started under the Biden administration was halted after the Trump administration cut the EPA division that would have continued it, Schechinger told Inside Climate News. Denmark, by contrast, is weighing a standard near 1.3 mg/L after concluding the medical savings would exceed the treatment costs.
The agriculture connection
Wastewater discharge contributes, but the dominant source is agricultural runoff. Synthetic fertilizer applied to feed crops and manure from concentrated animal feeding operations, or CAFOs, leaches into groundwater and washes into surface water. The two often co-locate: feedlots cluster near the corn that feeds them, multiplying the contamination load on a single watershed.
The geography of the EWG findings tracks that pattern almost perfectly. California, Pennsylvania, Washington, Kansas, North Carolina, New York, Nebraska, Texas, Arizona and Wisconsin together account for 60 percent of all water systems with elevated nitrate. Five states (California, Texas, Kansas, Nebraska and Oklahoma) contain 64 percent of all systems exceeding the legal limit.
A recent Yale study linked proximity to CAFOs with elevated cancer rates in California, Iowa and Texas, the country's leading producers of dairy, hogs and beef respectively. Nitrate-contaminated water was identified as a primary risk pathway.
In Kansas, the exposure is even more concentrated. According to Zack Pistora, who heads the state's Sierra Club chapter, the concentration of agricultural activity in Kansas means exposure rates are significantly higher than the national average. State regulators have found that 80 to 90 percent of Kansas waterways are impaired. Pistora noted that nitrates represent the primary contaminant in Kansas waterways.
Advocates in southwestern Kansas are currently fighting a proposed 88,000-head cattle feedlot in Finney County, near Garden City, an area already saturated with large CAFOs. Pistora questioned the wisdom of adding more cattle operations to areas already heavily impacted by agricultural pollution. Pistora argued that regulatory action is needed to control the expansion of concentrated animal feeding operations.
The climate feedback loop
Climate change makes the contamination problem worse, and agriculture makes climate change worse. Nitrous oxide released from fertilized soil is a heat-trapping gas hundreds of times more potent than carbon dioxide, and U.S. agriculture accounts for roughly 10 percent of national greenhouse gas emissions.
Warmer temperatures intensify the weather extremes that move nitrates around. Drought concentrates nitrogen in topsoil. When rain finally arrives (often as a heavy downpour rather than a gentle soaking), the runoff carries a larger pollutant load into rivers, lakes and aquifers.
Schechinger explained that the problem is cyclical: agricultural emissions contribute to climate change, which in turn exacerbates nitrate contamination.
What comes next
Three policy levers exist. The EPA could lower the maximum contaminant level to reflect six decades of research the current standard ignores. Congress could restructure farm subsidies to reward conservation rather than fertilizer-intensive monocultures. States could regulate CAFO siting and density more aggressively, particularly in watersheds already at or near the legal limit.
None of these are on a fast track. The federal review process has been dismantled. The Farm Bill cuts conservation funding rather than expanding it. State agencies in the most affected regions continue permitting new feedlots in already saturated areas.
For now, the 62 million Americans drinking elevated-nitrate water are scattered across cornfields and city blocks alike, an exposure map that scrambles the familiar story about which communities bear the costs of industrial agriculture. Their practical options are narrow: reverse osmosis filtration at the tap, ion-exchange systems for whole homes, or bottled water. None are free. A problem produced upstream, on land owned by someone else, gets paid for downstream — at the kitchen sink, on the utility bill, and eventually in the hospital.
