PFAS in Drinking Water
PFAS are long-lasting man-made chemicals. In April 2024 EPA set national limits including 4.0 parts per trillion (ppt) each for PFOA and PFOS. In May 2025 EPA said it would keep the PFOA and PFOS limits, propose more time to comply (to 2031), and reconsider the limits for other PFAS. New Hampshire has its own enforceable limits for PFOA, PFOS, PFHxS and PFNA set in 2020.
TapWaterPro system pages do not yet include PFAS sample results. Your system's annual water quality report lists any PFAS it detected.
Some filters are certified to NSF/ANSI 53 or 58 for PFOA/PFOS reduction; check the exact claim on NSF's listing.
Detection vs violation
- Detection: a lab found a substance. Many substances are detected at levels below the legal limit.
- MCL (legal limit): the highest level EPA allows. Going over it, usually as an average over time, is a violation.
- MCLG: a health goal with no enforcement. It can be zero (for lead it is zero).
- Action level (lead and copper): a trigger for extra steps such as corrosion control and public education. Exceeding it is not a violation by itself.
- Monitoring or reporting violation: a test or report was late or missing. It does not by itself mean a contaminant was too high.