MINNEAPOLIS – A new report from the Environmental Working Group shows the shocking extent of a widespread public health crisis: Over 122 million Americans drink water with high levels of cancer-causing disinfection byproduct chemicals.
Manure runoff from livestock factory farming operations contributes to the problem, as it reacts with public water systems’ disinfectants to create these byproducts.
EWG’s analysis of nationwide water test results from 2019 to 2023 found that nearly 6,000 community water systems across 49 states and Washington, D.C., had at least one instance of unsafe levels of the byproduct trihalomethanes, or TTHMs.
These toxic chemicals, linked to increased risks of bladder and colorectal cancer, as well as birth defects, are a direct result of the interaction between disinfectants and organic pollutants flowing into drinking water.
“This is a wake-up call,” said Anne Schechinger, EWG’s Midwest director and author of the report. “Manure from factory farms is polluting our water supplies, and when utilities try to make that water safe to drink, they unintentionally create another public health hazard that increases the risk of cancer and birth defects.”
Texas leads in water contamination
The report found that more than half the contaminated water systems were in just 10 states, many of which are the biggest states, with Texas leading the way. More than 700 Texas water systems – serving millions of residents – recorded TTHM levels above the Environmental Protection Agency’s legal limit of 80 parts per billion, or ppb.
Even more alarming, dozens of systems nationwide tested at double or even triple this threshold, exposing residents to serious health risks.
Key findings
The report shines a light on the severity and ubiquity of the problems caused by the massive amounts of manure factory farms produce and its role in disinfection byproducts. EWG found:
- Widespread contamination: Over 122 million people served by 5,919 water systems had drinking water with unsafe levels of cancer-causing disinfection byproducts at least once between 2019 and 2023.
- Manure runoff as a culprit: Livestock manure is one source that contaminates water and interacts with disinfectants like chlorine to create toxic TTHMs.
- Exceeding government safety limits: The water from systems in 49 states and Washington, D.C., tested at or above the EPA’s limit of 80 ppb for TTHMs, with some systems testing higher than 300 ppb.
- Health risks: Even at levels below EPA’s limit, TTHMs have been linked to bladder and colorectal cancer, low birth weight, stillbirths and birth defects.
- Most affected states: While Texas led the nation, with over 700 water systems exceeding EPA’s TTHM limit, other top states include California, Florida and North Carolina.
- Underfunded solutions: Despite these risks to public health, billions in federal agricultural conservation funding that could have prevented manure runoff were recently frozen by the Trump administration, while taxpayer money continues supporting the growth of factory farms.
Factory farms are swamped by a manure crisis
Industrial-scale animal factory farms generate enormous amounts of manure, which is commonly spread on farmland as fertilizer. However, excess manure washes into nearby rivers, lakes and streams, many of which supply drinking water to millions of Americans.
When utilities treat water containing organic matter with disinfectants like chlorine, the process creates toxic byproducts, including TTHMs. The problem is especially severe in rural areas, where livestock and crop farming is most concentrated.
Urgent need for action
Factory farms threaten our health by contaminating our food with pathogens, polluting our air and water, and threatening the efficacy of life-saving antibiotics. EWG’s report calls for immediate action to curb manure pollution and protect public health. These include:
- Stronger regulations: The EPA must impose stricter manure management rules on factory farms, including limits on manure application near drinking water sources.
- Expanded water treatment funding: To remove organic contaminants before disinfection, federal and state governments must invest in advanced water filtration systems, such as granular activated carbon and reverse osmosis.
- Incentives for sustainable farming: Conservation programs should prioritize funding for practices that prevent manure runoff, such as stream buffers and cover crops.
- Purchasing non-factory-farmed meat: Consumers can buy meat and dairy products from farms that produce livestock outside of factory farms, on grass.
“This crisis is preventable,” Schechinger said. “Farmers, regulators and policymakers must take the responsibility of ensuring that food production does not come at such a steep cost to public health.”
Consumers can take immediate action by using EWG’s Tap Water Database to check for contaminants in their drinking water and find the best filtration options for their homes.
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The Environmental Working Group (EWG) 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.
