Tap water flowing to parts of Cabarrus County, North Carolina, contains per- and polyfluoroalkyl substances, commonly called PFAS or “forever chemicals,” at concentrations that meet or exceed the federal maximum contaminant level. The contamination traces back to water sourced from Concord’s Hillgrove Water Treatment Plant, which feeds into the supply serving the Town of Harrisburg and surrounding communities. With enforceable federal limits now on the books and compliance deadlines approaching, the findings put local utilities under pressure to act before regulators step in.
What Testing Revealed at the Hillgrove Plant
The Town of Harrisburg disclosed that PFAS levels in water sourced from Concord’s Hillgrove Water Treatment Plant are at or above the federal Maximum Contaminant Level. The town draws from a complex network of 10 intakes spanning wells, Charlotte’s water system, and Concord’s supply, meaning that not every tap in the service area carries the same concentration at any given time. That blended sourcing arrangement is central to Harrisburg’s position that it has no current violations, because compliance under the EPA’s PFAS rule hinges on running annual averages rather than single-sample readings.
But the blending math cuts both ways. If the Hillgrove intake consistently delivers water at or above the limit, households that happen to receive a higher proportion of Concord-sourced water on a given day could face exposure spikes that the annual average obscures. Targeted, intake-level sampling would clarify whether certain neighborhoods bear a disproportionate share of the risk. Without that granularity, the running-average framework may offer statistical comfort while leaving real gaps in public health protection.
Federal Limits and What They Mean for Residents
The EPA’s final PFAS National Primary Drinking Water Regulation sets enforceable maximum contaminant levels of 4 parts per trillion for PFOA and PFOS, two of the most studied forever chemicals. Three additional compounds, PFHxS, PFNA, and GenX (also known as HFPO-DA), carry a limit of 10 parts per trillion each. The rule also introduces a Hazard Index for mixtures of these substances, recognizing that combined exposure to multiple PFAS compounds can pose health risks even when individual chemicals fall below their standalone caps.
For a family in Harrisburg, these numbers translate into a straightforward question: is the water safe to drink today, or only safe on paper once averaged across a year? Because compliance is calculated on running annual averages, a system can record individual samples above 4 ppt for PFOA or PFOS and still avoid a formal violation as long as the yearly math stays below the line. The EPA recently confirmed it will keep the maximum contaminant levels for PFOA and PFOS unchanged, though the agency is proposing adjustments to compliance timelines and exemptions for other regulated PFAS. That means the 4 ppt threshold is not going away, and utilities that have been waiting for a regulatory softening will need to invest in treatment or alternative sourcing.
North Carolina’s Broader PFAS Monitoring Picture
Cabarrus County’s situation sits within a statewide pattern. The North Carolina Department of Environmental Quality has conducted PFAS sampling of public water systems across the state, selecting systems for follow-up testing based on earlier detections. Data tables covering municipal and county systems from 2022 and small systems from 2023 and 2024 show that PFAS contamination is not confined to the well-known GenX crisis along the Cape Fear River. Smaller community water systems in and near Cabarrus County have also recorded detectable levels of PFOS, PFOA, GenX, PFBS, PFNA, and PFHxS, according to the 2023 small-system sampling data table, which reports results in nanograms per liter by system name, county, sample date, and source water type…