A typical laboratory test report for per- and polyfluoroalkyl substances (PFAS) in water lists detected concentrations in micrograms per liter, often expressed here as nanograms per liter (ng/L) or parts per trillion (ppt). For instance, recent data for Charles Town’s public water system, Walnut Grove Utilities, reports PFOA and PFOS detections at levels like 0.0042 µg/L (4.2 ng/L) and 0.0173 µg/L (17.3 ng/L). These figures measure the presence of these persistent fluorinated compounds, sometimes called "forever chemicals." It is important to note that a detection is not a violation or an indication of unsafe water but an instrument reading above a certain sensitivity level.
How UCMR5 Monitoring Expands on UCMR3 in PFAS Detection and Thresholds
The Environmental Protection Agency’s Unregulated Contaminant Monitoring Rule (UCMR) is a survey program that tests public water systems for contaminants without necessarily enforcing health-based limits. The current UCMR5 monitors for a broader range of PFAS compounds than the earlier UCMR3, including PFOA, PFOS, PFHxS, PFNA, and several others. Reporting levels are set very low, often near parts per trillion, reflecting advances in detection technology.
In Jefferson County's Walnut Grove Utilities system, UCMR5 data shows multiple detections: one for PFOA above 0.004 µg/L, six for PFOS above the same reporting level, and some detections of other fluorinated substances below their health thresholds. This contrasts with UCMR3, which monitored fewer compounds and at different sensitivity. These differences mean current data gives a more detailed picture of PFAS presence but does not imply increased risk by itself.
Why Aesthetic Secondary Standards Differ from Health-Based Limits for PFAS
Water quality standards distinguish legal health limits from secondary standards that address taste, staining, or corrosivity. For PFAS, federal maximum contaminant levels (MCLs) for PFOA and PFOS were established recently at 4 ng/L (4 parts per trillion) for health-based protection. Exceeding a reporting level or detecting a substance does not equal exceeding a health-based MCL.
Charles Town’s water records show detections of PFOA and PFOS slightly above the 4 ng/L MCL in some samples, but these are federal survey results, not compliance enforcement test results. Presence affecting aesthetic qualities would relate to other parameters, not PFAS, which are primarily a chemical contamination concern. Understanding this difference helps clarify that the presence of PFAS in water is being observed and studied rather than necessarily posing immediate health risks under current standards.
Firefighting Foam, Textile Finishing, and Landfill Sources: Which Are Reflected in Jefferson County’s Record?
PFAS compounds historically entered water systems through industrial uses such as aqueous film-forming foam (AFFF) in firefighting, textile finishing, and landfill leachate. The distribution of detections in the Walnut Grove Utilities system suggests some influence consistent with surface water impacted by such sources, though specific local industrial activities are not detailed in the EPA data.
The surface water source for Charles Town may receive trace PFAS contributions from legacy firefighting foam use or industrial processes within or near Jefferson County. No single source is directly identified by the public system monitoring data, but patterns match common regional sources recognized nationally.
What Changes for a Large Household, a Second Home, or a Seasonal Property?
The water quality recorded for the public system serves over 3,000 connections, including single-family homes, businesses, and seasonal properties. For a large household or a second home, the water entering each connection reflects the system’s average conditions, not localized contamination.
Higher water use or seasonal occupancy does not alter the water’s PFAS status but may influence decisions about whether to use home water treatment equipment that addresses PFAS. Testing water individually at each property is necessary to establish the exact PFAS content for that location.
How to Compare Jefferson County’s PFAS Record With Neighbouring Regions Without Overreading It
Comparing PFAS detection data across counties requires caution. Each public water system serves different sources and population patterns, and detection frequencies are influenced by monitoring programs and local environmental conditions.
Jefferson County’s Walnut Grove Utilities shows some PFAS detections above reporting levels but not widespread exceedances of health thresholds. Neighbouring counties may have different patterns based on their water sources and industrial history. Neither record alone defines the safety or quality of water in any individual home.
Why PFOA and PFOS Are Measured in Nanograms Per Litre and What Four Decimal Places Mean
PFAS compounds like PFOA and PFOS exist in water at extremely low concentrations, measured in nanograms per litre (ng/L), equivalent to parts per trillion (ppt). Reporting these values to four decimal places reflects the precision of modern analytical instruments, not necessarily meaningful differences in health risk.
A detection of 0.0042 µg/L (4.2 ng/L) indicates the instrument can reliably measure PFAS at that scale, which is roughly one drop of contamination in an Olympic-sized swimming pool. This sensitivity allows regulators to monitor trends and manage water quality proactively, not to assert danger at those levels.
In summary, government testing shows that PFAS compounds, including PFOA and PFOS, are detected at low levels in Charles Town’s surface water supply, sometimes near or slightly above reporting levels and recent federal MCLs. This page has clarified how sampling programs differ, why detection is not violation, and what sources contribute to the pattern observed. For households concerned about individual water quality, testing is the only way to know exact PFAS levels; the Fleck PFAS Forever Chemicals Filter provides a documented solution to reduce these substances from water at the point of use.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2025-10-21. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR5 monitoring (2023-2025) for WALNUT GROVE UTILITIES (WV3301942), WV: 180 results across 10 listed contaminants, 29 detections above the reporting level; 7 results above a 2024 federal MCL
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