Contamination of private water wells by toxic metals is alarmingly common statewide, according to a recent analysis. Contaminants include lead, arsenic, and unhealthy levels of manganese.
Lauren Eaves, a PhD candidate in environmental sciences and engineering at UNC and the lead author on the study, describes the maximum levels of toxic metals she found as “really, deeply disturbing.” The worst-contaminated wells contained levels of arsenic over eighty times the EPA limit, or levels of lead thousands of times over the limit. And while those extremes weren’t typical of most wells tested, dangerously high levels weren’t infrequent. In some counties, over 10% of tests were over EPA limits for arsenic or lead.
Chronic arsenic exposure can cause cancer, and lead is an insidious neurotoxin that is especially dangerous for young children. Manganese is a necessary nutrient at low doses, but was often present in well water at high enough concentrations to be unhealthy.
The locations of contaminated wells suggest that toxins come from several sources.
“The patterns that you see for arsenic contamination and for manganese are reflective of the underlying geology of the state,” explains Rebecca Fry, a contributor to the study and the director of the UNC Superfund Research Program. Arsenic and manganese levels were highest in a broad stripe of the Piedmont, matching an underlying band of bedrock that likely leaches toxic metals into local groundwater.
Lead contamination, on the other hand, was most common in or near urban areas, and probably comes from corrosion of lead pipes, according to the researchers. Although both private well users and municipal water users may have lead pipes, well water is more likely to corrode the pipes, which puts well users at increased risk.
People can check if metal contamination is common in their area using an interactive online map that includes data from the study.
Fry and Eaves both emphasize that water contamination is a health equity issue. Communities of color at the edges of towns and cities are especially likely to be excluded from city services, including public water, explains Eaves.
“The odds of exclusion from public water in Wake County are dependent on the percentage of African Americans in that census block,” Eaves said. “Depending on the racial composition of the neighborhood, the likelihood of being on private wells shifts… your likelihood of exposure to toxic chemicals shifts.”
Well testing, water filters, and expanded public water services could lower risks
While the results are alarming, the patterns of contamination suggest ways to limit metal exposure.
“By using this information, we could really prioritize areas that have high risk of chemical exposure in drinking water and could benefit most from public water supply lines,” Fry said.
The researchers say that expanding municipal water lines to communities that are most affected would be a crucial step forward.
Meanwhile, people on well water can take steps to reduce their risk of exposure to toxins.
“It’s really important for people with private wells to test their wells regularly,” said Virginia Guidry, the branch head for occupational and environmental epidemiology at the North Carolina Department of Health and Human Services. “Sometimes well owners don't test their water because they think the water tastes fine, smells fine, looks fine. The challenge is that some contaminants don't have a taste or smell so you can't always know unless you test the well water.”
The North Carolina Department of Health and Human Services recommends that people test their wells for toxic metals every two years. People who find contamination, but can’t afford a water filter, can apply for financial support through the Bernard Allen Fund by contacting their county health department.