The City of Patterson has notified water customers that the municipal water system is currently in violation of the maximum contaminant level for total trihalomethanes, or TTHMs.
In a notice dated September 22 and titled “TTHM 3rd Quarter Violation 2026,” the city said second-quarter compliance calculations showed locational running annual averages of 89 parts per billion at a testing location on Kem Street and 84 parts per billion at a location on Taft Street. The federal limit for TTHMs is 80 parts per billion.
TTHMs are disinfection byproducts that can form when disinfectants used to treat drinking water react with naturally occurring organic and inorganic matter. According to the notice, long-term exposure to TTHM levels above the federal standard may cause liver, kidney or central nervous system problems and may increase the risk of cancer.
City officials emphasized that the violation is not an emergency and that the water remains safe to drink. The Environmental Protection Agency and Louisiana Department of Health do not consider the violation a serious health risk from short-term exposure.
The city said it is working on solutions to correct the problem. Residents are asked to share the notice with others who may not have received it directly, including people in apartments, nursing homes, schools and businesses.
For additional information, contact Patterson Water Plant Supervisor Sharon Gillum at 985-992-8105.
