An Analysis of Water Quality in Public Water Systems, Private Wells, Groundwater, and Surface Water in North Carolina

Abstract

Clean drinking water is essential for human life. The quality of publicly supplied drinking water is regulated by the Safe Drinking Water Act with maximum contaminant levels established for over ninety contaminants; however, the quality of private well water is not regulated. In this study, the quality of publicly supplied water and private well water was compared for nine counties in North Carolina with a focus on lead, copper, arsenic, iron, and manganese. Additionally, the quality of surface water and groundwater was analyzed for the nine counties since they serve as sources for the drinking water. Water quality data were obtained from publicly available sources including the North Carolina Department of Health and Human Services, Annual Drinking Water Quality Reports, and the United States Geological Survey Water Quality Portal. Upon analysis, private well water was found to have higher concentrations of lead, arsenic, iron, and manganese than publicly supplied water, thus highlighting the disparity between those relying on private well water and those with access to publicly supplied water. Private well water was found to have higher concentrations of lead than groundwater, indicating that lead likely enters the water from the corrosion of older plumbing systems that used metal pipes and plumbing. Copper also likely enters drinking water through the corrosion of older plumbing systems since private well water and publicly supplied water were found to have higher concentrations of copper than groundwater and surface water. Rural counties had higher concentrations of copper in publicly supplied water compared to urban counties, suggesting that the rural counties may have older plumbing systems. Publicly supplied water is filtered during drinking water treatment, likely removing arsenic, iron, and manganese. This was evidenced because the surface water, which publicly supplied water is sourced from, had higher concentrations of these contaminants compared to the publicly supplied water. Location played a role in the concentration of contaminants with high levels of arsenic found in counties known to have arsenic-containing rocks underground and counties in the Piedmont region having high concentrations of manganese. Overall, those relying on private wells are more likely to be exposed to drinking water contaminants than those with publicly supplied water, although it is important for all to have their water tested regularly to ensure it is safe and to help limit exposure to contaminants.