A report Wednesday on the health of the nation’s drinking water says Charlotte’s water contains chemicals that could make consumers sick.
The Environmental Working Group report acknowledges that the contaminants – byproducts of chlorine disinfection of water – are within federal safety limits.
But it disagrees with Charlotte Water, the city’s utility, on whether those contaminants still pose health risks.
The chemicals are known as trihalomethanes, or TTHMs for short. They form when chlorine used to disinfect drinking water reacts with natural organic matter in warm weather.
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The federal Centers for Disease Control and Prevention says large doses of TTHMs can cause liver damage and decreased nervous system activity. The chemicals have caused cancer in lab rats.
Charlotte Water’s most recent water-quality report, for 2016, said TTHMs averaged 51.7 parts per billion. That number is now 47.9 ppb, the utility said Wednesday, well below the 80 ppb safety standard set by the Environmental Protection Agency.
The report released Wednesday cited Charlotte data from 2015, showing TTHMs at 64.3 ppb, double the state and national averages.
The 2015 data is misleading, Charlotte Water spokeswoman Jennifer Frost said, because it reflects temporarily elevated TTHMs that were traced to coal treatment at a Duke Energy power plant on Lake Norman. The utility alerted the public to the spike, which later dissipated.
The Environmental Working Group also compared Charlotte’s TTHM levels to a draft “public health goal” set by the state of California. That guideline says TTHMs levels need to be 100 times lower than the federal standard – no higher than 0.8 ppb – to protect against cancer.
Charlotte Water says California’s guidelines are specific to that state. North Carolina has no similar guidelines other than the federal standard set by EPA.
Frost said the report incorrectly implies that Charlotte’s water is less than safe.
“The quality of Charlotte’s drinking water and the health and safety implications to our community are too serious to misrepresent,” she said by email. “We encourage the public to review the data for themselves, understand the information and ask Charlotte Water any questions about our services.”
The city’s treatment processes reduce organic materials in water, before chlorine is added, to control disinfection byproducts, Frost said. To further reduce formation of the chemicals, she said, Charlotte Water uses flushing devices in its 4,200 miles of water lines and operates its elevated storage tanks at lower levels in summer.
Nneka Leiba, director of healthy living science for the Environmental Working Group, said blame doesn’t rest with water utilities.
“We don’t think the onus should be on the utilities,” she said. “For the most part, utilities are doing the best they can.”
The fault, Leiba said, lies with federal standards that “are a compromise between health and political and economic limits.” If stringent standards would be costly to meet, she said, regulators relax them.
The result of those regulations, the group maintains, is polluted water supplies such as the organic material that helps form disinfection byproducts.