What changed for a household this month: rules, data, product tests, studies. One dated issue a month, every item sourced, nothing edited after it is published.
Issue 1 31 October 2026
What changed for a household in October 2026: the federal drinking-water limits are still the 2024 rule, EPA's final UCMR 5 dataset is out (and now searchable here by ZIP), a study says the monitoring undercounts, and an overlooked PFAS turned up in most tap and bottled drinks tested.
The 4 ng/L PFOA and PFOS limits still apply; the May 2026 proposals are not final
EPA proposed in May 2026 to keep the 4.0 ng/L limits for PFOA and PFOS, give systems until 2031 to comply, and rescind the 2024 limits for PFHxS, PFNA, HFPO-DA and the mixture index. Public comment closed on 20 July 2026. Two independent trackers that searched the Federal Register in early October found no final rule, so the 2024 rule — and its monitoring and reporting deadlines — remains the law. For a household: a PFOA or PFOS result at or above 4 ng/L is still above the federal limit, whatever the compliance date becomes.
EPA's final UCMR 5 dataset is out — look up your own water system
The final UCMR 5 occurrence data (2023–2025, 29 PFAS, 10,313 public water systems; file dated 15 October 2026) is published. We aggregated it per system: 3,595 systems reported at least one PFAS detection; PFOA was detected (that is, at or above 4 ng/L) in 1,305 systems and PFOS in 1,352. You can now read your own system's results by ZIP code on this site.
A study argues the federal data undercounts PFAS by about half
Researchers re-analysed EPA's January 2026 PFAS monitoring release, in which roughly 98 % of 1.86 million results sat below laboratory reporting limits and are conventionally treated as zero. Modelling those below-limit results instead of zeroing them, they estimated that PFAS occurrence in US drinking water could be more than twice what the standard method yields. The practical reading is the one this site already prints next to every lookup: ask what "not detected" means in your report — for PFOA and PFOS it means below 4 ng/L, not absent.
TFA, an overlooked PFAS, in most tap water and bottled drinks tested
A study in the October issue of Environmental Science & Technology Letters tested tap water across New Jersey and a range of bottled beverages and found trifluoroacetic acid (TFA) — a very short-chain PFAS that standard monitoring does not target — in more than 91 % of tap samples and nearly 80 % of bottled drinks; formulated drinks such as sports and electrolyte waters carried on average 52 times more TFA than plain bottled water. TFA is not in UCMR 5 and is not removed by the certifications the Index relies on; it is a watch item, not an action item, until the evidence on health effects and filtration settles.