Millions of people across the United States could be drinking water contaminated with dangerous levels of substances created when utilities disinfect water tainted with animal manure and other pollutants. An analysis of testing results from community water systems in 49 states found that nearly 6,000 such systems serving 122 million people recorded an unsafe level of chemicals known as trihalomethanes at least once during testing from 2019 to 2023. The chemicals are byproducts created when chlorine or other disinfectants used by water systems interact with organic matter, such as decaying leaves, vegetation, human or animal waste and other substances. One or more of these chemicals chloroform, bromodichloromethane, dibromochloromethane, and bromoform " have been linked to various human health risks, including cancers. Texas water systems had the highest prevalence of water systems with unsafe levels of TTHMs, with more than 700 such systems serving over 8.6 million people reporting the contaminants above the EPA's 80 ppb, according to the report issued April 10 by the Environmental Working Group (EWG). "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," Anne Schechinger, EWG's Midwest director, said.