Charlotte Water Meets Standards But Test Results Indicate Elevated THMs

During a recent quarterly water sampling, Charlotte Water in August detected elevated levels of disinfection by-products known as trihalomethanes (THMs) in some locations, but advises that the water is safe to use for drinking, cooking, bathing and swimming as it meets federal Safe Drinking Water Act requirements.

“We want to emphasize that our drinking water is in compliance with U.S. Environmental Protection Agency (EPA) Safe Drinking Water and N.C. Department of Environment and Natural Resources (DENR) requirements,” said Charlotte Water Director Barry Gullet. “We have implemented multiple proactive measures including decreasing the volume of water stored in elevated water tanks, strategically flushing water through hydrants, optimizing existing treatment processes within the plants and developing a new treatment process that lowers the pH of drinking water to reduce THM formation by up to 40 percent.”

The most recent round of quarterly samples analyzed this week found elevated THM levels at eight of the 12 designated sampling locations. The running annual averages at each of the 12 locations range from 0.0533 ppm to 0.0789 ppm and comply with U.S. EPA and NC DENR drinking water requirements, so the drinking water meets the standard and there are no violations.

Customers at the sampling locations with individual test results greater than 0.080 ppm were notified today by hand delivered letters per North Carolina regulatory requirements. (Notification must take place within 48 hours of the sample results).

THMs are formed when chlorine, a chemical used to kill bacteria, reacts with other compounds. Charlotte Water has seen recent increases of bromide in the water supply. Bromide can enter the lakes due to a variety of sources. THM formation increases as water temperatures rise and as water age increases.  This is exacerbated by the hot summer weather.

Charlotte Water is continuing to address this situation. More information will be available after 4 p.m. and