Interpreting Laboratory Test Reports for PFAS Mixtures in Residential Water
A typical laboratory report for PFAS, per- and polyfluoroalkyl substances, lists measured concentrations of multiple compounds expressed in nanograms per liter (ng/L) or parts per trillion (ppt). These include PFOA, PFOS, PFHxS, PFNA, and others. Importantly, a report shows whether each compound is detected above a certain reporting level. Detection indicates measurement by sensitive instruments, not necessarily a problem or violation. In VI, the public water system record shows no detections above reporting levels for these compounds.
Hazard Index for PFAS Mixtures and Federal 2024 MCLs
Experts calculate hazard indices to assess combined potential health effects from multiple PFAS compounds, but such indices are informed by complex toxicological data and do not establish safety in an individual home’s water. Among the fluorinated compounds monitored in VI, federal Maximum Contaminant Levels (MCLs) effective in 2024 apply only to PFOA and PFOS at 4 ng/L, and PFHxS, PFNA, and HFPO-DA at 10 ng/L. The system’s sampling record shows no detections above these MCLs. Other compounds listed in testing results do not currently have federal MCLs.
Which Residential Fixtures and Appliances Are Most Affected by PFAS
PFAS occur uniformly in the water supply entering a household, so faucets, ice makers, coffee machines, and other appliances using water are all potentially impacted to the same extent. Because 'forever chemicals' resist breakdown, they accumulate in water-using devices over time. Prioritizing treatment at the point of entry can reduce PFAS in all water outlets, while point-of-use options treat specific fixtures selectively. Understanding which devices are used most for drinking or cooking helps in evaluating treatment placement.
Sample Size and Water Source Considerations Behind PFAS Figures in VI
The VI public water system's PFAS data comes from 4 samples collected between November 2023 and June 2024 under the federal Unregulated Contaminant Monitoring Rule (UCMR5). Sampling reflects the system-wide water source, not any single household’s plumbing. While 4 samples provide a snapshot indicating no detections above reporting levels, this relatively small dataset means individual household water quality can only be confirmed by specific private testing. The public system’s zero health-based violation record confirms regulatory compliance but does not predict every home’s individual water.
How the C-Series System Addresses PFAS in Residential Water
The C-Series PFAS Forever Chemicals Filter is engineered to reduce a broad spectrum of PFAS compounds from residential water supplies. Its technology employs advanced filtration media designed to adsorb fluorinated compounds, including those with and without federal MCLs. This approach can be configured for whole-house treatment or targeted to specific water lines. By lowering PFAS concentrations in treated water, the C-Series system helps households manage 'forever chemicals' regardless of their initial detected levels in the public water system.
Differences Between UCMR5 and UCMR3 PFAS Monitoring in VI
UCMR5, conducted from 2023 to 2025, includes a wider range of PFAS compounds with lower reporting levels compared to UCMR3, the prior monitoring cycle. For VI’s system, UCMR5 detected no PFAS above reporting levels, while UCMR3 may have targeted fewer compounds or applied higher detection thresholds. The expanded compound list and enhanced sensitivity in UCMR5 provide a more thorough characterization of fluorinated substances in the water supply, helping residents understand the latest data context.
When weighing technical approaches for managing PFAS at home, refer to your own measured household demand and tested water quality. The C-Series PFAS Forever Chemicals Filter ships ready to configure for a custom fit and can be an effective option to address concerns arising from detected PFAS, including those noted in federal monitoring of the VI public water system.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2024-06-24. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR5 monitoring (2023-2025) for WATER AND POWER AUTHORITY-STT (VI0000443), VI: 40 results across 10 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level