Flint, Mich., has drawn the attention no city wants: tainted drinking water. Should Charlotte residents be worried too?
No, according to citywide water tests. But homeowners with old plumbing might want to take precautions.
Two years ago, the water supply for financially struggling Flint was switched from Lake Huron to the Flint River. The river water corroded the lead service lines that pipe water to about half Flint’s homes. Lead, which can cause brain damage and lower IQs in children, coursed across the city.
“It’s important to know that it could happen in any city,” said Hope Taylor, executive director of the advocacy group Clean Water for North Carolina. She served on the National Drinking Water Advisory Council, which advises the Environmental Protection Agency, from 2009 to 2011.
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Many cities still have lead service lines, Taylor said, most often in poor and non-white neighborhoods like Flint’s. Washington, D.C., found a lead outbreak in its water supply more than a decade ago.
Changes in the chemicals used to treat drinking water have been linked to high blood lead levels found in children in Greenville, N.C., Durham, and Wayne County, according to a 2009 article in the journal Environmental Health Perspectives.
Lead most often gets into water from corroding lines or the lead solder that connects them.
Because of a congressional ban on plumbing materials that contain lead, Charlotte homes built after 1988 are far less likely to have lead solder than older ones, the city’s water utility says. About 60 percent of Charlotte Water’s distribution system, the 4,000-mile network of lines, was built after 1990.
“Our practice is to replace lead service lines when found,” said utility spokeswoman Jennifer Frost. “It’s a rare occurrence. Our water treatment staff believes the last lead service line was replaced in the early ’90s.”
Charlotte is required to test drinking water for lead every three years. The most recent results, in 2013, found 90 percent of the water samples with lead levels at 7 parts per billion or lower. The federal “action level” – the point at which utilities have to corrective action – is 15 ppb.
Samples at three homes among the 53 tested found lead higher than the action level. The utility says it notified the residents of the results and how to reduce lead. The utility uses lime to adjust water’s pH to prevent pipe corrosion.
“It is fairly typical for a large water system to have some individual samples exceed (15 ppb) without the whole system exceeding the lead action level,” the Department of Environmental Quality said.
The only way to know if your own home’s tap water has high lead levels is to test it, says the Centers for Disease Control, which offers tips for minimizing potential harm.
Few U.S. outbreaks
Charlotte Water tests for more than 150 contaminants. Some have safety thresholds because they’re known to be harmful. Others are monitored, without enforceable limits, while research into them continues.
That does not mean the more than 60,000 other chemicals in use in the U.S. are harmless. Federal standards have been created for only 87 chemicals and other contaminants.
Still, “the Safe Drinking Water Act works real well, if you look at the incidence of disease compared to the rest of the world,” said Gary Silverman, a UNC Charlotte public health professor who researches environmental health and water quality.
The last major disease outbreak from public water supplies was in 1993, he said, when cryptosporidium, a microbe in fecal waste, sickened 400,000 people and killed 104 in Milwaukee. Federal water treatment standards changed as a result.
Waterborne diseases killed seven people in the U.S. in 2009-10, the most recent year for which data is available. Worldwide, Silverman said, bad water kills millions each year.
State regulators in April cited Charlotte Water for missing quarterly sampling in February for disinfection byproducts that can be toxic. The utility says two of the required 12 sampling sites were temporarily inaccessible, causing the error.
Charlotte Water says it is alert to potential problems.
Last August, city officials called a press conference to report a spike in disinfection byproducts called trihalomethanes. While THM levels didn’t break federal standards, the chemicals can worsen liver, kidney or central nervous system problems and may increase cancer risks.
The city traced the likely source to Duke Energy, which used a THM-forming solution to wash coal at a power plant on Lake Norman. Duke stopped using the solution, which was intended to reduce air releases of toxic mercury when coal is burned. Bromide levels in raw water have dropped since then, Charlotte Water says.
Power plants are among hundreds of threats to Charlotte’s water supply, according to the state Source Water Assessment Program.
The program combines natural contours with potential contamination sources such as chemical tanks to calculated susceptibility ratings for water systems. Charlotte’s major and secondary water sources, Mountain Island Lake and Lake Norman, were ranked in the most vulnerable category.
Most disease outbreaks come not from public water systems but from private wells, UNCC’s Silverman said. In North Carolina, private wells are essentially unregulated.
“A lot of it is due to no one checking,” Silverman said. “You get a permit and then years go by and no one checks again. That’s much more of a threat in terms of disease.”
UNCC researchers recently began on a five-year study of Gaston County wells funded by a Centers for Disease Control grant.
An estimated 15 percent of Mecklenburg County residents rely on groundwater. The county requires that new residential wells be tested for bacteria, nitrate and metals, and volatile chemicals if the well is near underground tanks or industrial areas.
Beyond that, “it’s your well and you decide what you want,” said Lisa Corbitt, groundwater services program manager.
To protect well owners, Mecklenburg has documented 1,542 sites with soil or groundwater contamination and has identified 270 contaminated wells around them.
The county recommends that private well owners have their water tested once a year for bacteria and nitrates, which can cause a potentially fatal blood disorder in babies.
More on lead and other water contaminants
Charlotte Water’s annual water quality reports: http://charmeck.org/city/charlotte/Utilities/PublicationsandEducation/Pages/waterqualityreports.aspx
Mecklenburg County well testing form
Tips on lead in tap water