NEW HANOVER COUNTY —Fluoride was detected at double the federal limit early this morning in the public water supply in New Hanover County, but the Cape Fear Public Utility Authority has no answers for how it happened.

In at least one location north of Wilmington, Cape Fear Public Utility Authority tested a sample at 8 milligrams per liter before 5 a.m. this morning, according to North Carolina Department of Environmental Quality’s Regional Engineering Supervisor Hedi Cox.

The federal maximum amount of fluoride allowed in public water systems is 4.0 milligrams per liter. The recommended guideline for the Environmental Protection Agency is 2.0 milligrams per liter.

Despite issuing a “do not drink” advisory to nearly 30,000 customers due to an “abundance of fluoride” in the water, CFPUA has been unable to offer an answer to the question on everyone’s mind: How long have the levels been elevated?

“It could have been an equipment malfunction but we don’t know at this time,” Carel Vandermeyden, CFPUA’s director of engineering said. “We started sampling before 5 a.m. this morning and saw fluoride levels in water leaving the water treatment plant were above state regulatory levels.”

Why the warning was issued

Cox said the public notice was issued as a precaution – not because CFPUA was required to. Only official “compliance samples” required by the DEQ approximately twice a month can trigger a mandatory public notice, Cox said.

However, the samples taken by CFPUA showed levels that would have triggered a notice.

“An exceedance of the 4 milligram-per-liter compliance sample could trigger a public notice,” Cox said.

With levels at one test site reaching double the federal limits and four times the EPA suggested guidelines, CFPUA decided to issue a warning, according to Cox.

“It was not a federal requirement that they issued any kind of notice for what happened today but they issued it anyway,” Cox said. “I believe it was 8 milligrams per liter at one location.”

When fluoride is in excess of 2 milligrams per liter, it can cause skin or tooth discoloration, according to the EPA. With one sample showing quadruple the EPA’s recommended level, it’s unclear whether there will be acute health effects.

CFPUA warned that failure to follow its initial advisory could result in “illness,” but did not provide specific symptoms or adverse health effects. According to an email sent by CFPUA, crews have been flushing the system and are making positive progress.

Levels returning to normal

“Around 9 a.m. the levels were coming in at below state regulatory levels. Once the sampling for New Hanover County is complete and the results are positive we will change the advisory for the entire area,” Vandermeyden said. “A smaller area will likely have a boil water advisory due to low water pressure caused by flushing.”