We're kicking off this initiative with the fact that surprised us most once we started digging: Weymouth's own municipal water — drawn from Great Pond, a supplemental pumping station at Whitman's Pond, and five bedrock wells in the Mill River Aquifer — tested for combined PFAS6 at just ND to 11.4 parts per trillion in 2025, comfortably under Massachusetts' 20 ppt standard. Lead came back clean too: a 90th-percentile reading of just 1 ppb against a 15 ppb federal action level.
And yet Weymouth is also home to one of the more serious documented PFAS contamination sites in the state. The former South Weymouth Naval Air Station, a 1,444-acre Superfund site now being redeveloped as "SouthField," has on-site groundwater readings from 2018 in the tens of thousands of parts per trillion — a combined PFOA/PFOS result around 256,000 ppt, thousands of times over the federal limit — the legacy of decades of firefighting-foam training exercises. That contamination is under active federal cleanup and sits in a different aquifer than the wells the town actually drinks from. Two real, well-documented, and completely different water stories, both true of the same town at the same time — which is exactly the kind of nuance we think deserves a plain-language home.
There's more texture underneath both: a lead service line inventory that's still resolving a few hundred "unknown" records, a single old tracker entry for a 1997 radium violation that no other source shows, and a town now moving to leave its own independent supply behind for a regional MWRA connection. See the full breakdown on our Water data page.
Long before there was a federal PFAS rule, there was a Massachusetts one. In October 2020, MassDEP finalized an enforceable drinking water standard — a Maximum Contaminant Level, or MCL — of 20 parts per trillion for the combined total of six PFAS compounds, a grouping the state calls "PFAS6": PFOS, PFOA, PFHxS, PFNA, PFHpA, and PFDA.
At the time, this made Massachusetts one of a small number of states with any enforceable PFAS standard at all. For the Weymouth Water Department, this is the exact standard its combined PFAS6 results have consistently stayed well under — ND to 11.4 ppt as of 2025 — a genuinely clean result by the state's own yardstick.
Source: Mass.gov — Massachusetts PFAS Drinking Water Standard (MCL).
Until April 2024, there was no federal limit on PFAS in drinking water at all — only the Massachusetts state standard set in 2020. That changed when EPA finalized its National Primary Drinking Water Regulation (NPDWR) for PFAS: the first time PFAS compounds have been individually, enforceably regulated at the federal level.
The rule set limits of 4 parts per trillion (ppt) each for PFOA and PFOS, 10 ppt each for three additional compounds (PFHxS, PFNA, and HFPO-DA), and a combined "Hazard Index" limit for mixtures of those plus PFBS. Water systems nationwide were given until 2027 to complete initial monitoring and until 2029 to come into full compliance.
For Weymouth, there's a real limit to what we can confirm here: the town's own Consumer Confidence Report reports combined PFAS6 results but doesn't break individual compounds out by their own specific ppt values, so we can't independently verify PFOA and PFOS separately meet the new 4 ppt individual limits — only that the combined figure is well under the state's broader 20 ppt threshold. That's a gap in the public reporting worth flagging, not a reason for alarm on its own.
Source: Federal Register — PFAS National Primary Drinking Water Regulation.
We're not going to soften this and we're not going to overstate it either: Weymouth's own municipal water system has a genuinely clean recent PFAS record. Combined PFAS6 testing in 2025 came back at ND to 11.4 parts per trillion, well under Massachusetts' 20 ppt standard, and unregulated UCMR5 testing found only trace levels of PFBA, PFBS, and PFHxA — compounds with no established enforceable limit.
That clean result sits a few miles from a genuinely serious PFAS site: the former South Weymouth Naval Air Station, where 2018 groundwater sampling found combined PFOA/PFOS readings around 256,000 parts per trillion — a legacy of firefighting-foam training exercises, now under active federal Superfund cleanup. That contamination is not in Weymouth's drinking water wells. Both facts are true, and neither should be used to obscure the other.
See the full compound-by-compound breakdown, including what we can and can't confirm, on our Water data page.
On May 18, 2026, EPA announced two proposals that affect the federal PFAS rule described above. The first (Docket EPA-HQ-OW-2025-1742) would let water systems request a two-year extension — from 2029 to 2031 — to comply with the enforceable limits for PFOA and PFOS, while requiring systems measuring 12 ppt or higher to take short-term mitigation action during the extension. The second (Docket EPA-HQ-OW-2025-0654) would rescind the individual limits for three other PFAS compounds (PFHxS, PFNA, and HFPO-DA/GenX) and the combined "Hazard Index" limit for mixtures of those plus PFBS, on the grounds that EPA says the prior process didn't follow required Safe Drinking Water Act procedure.
What doesn't change: the 4 ppt limits for PFOA and PFOS individually are not part of either rescission proposal. For a system like Weymouth's, where the town's own CCR doesn't break out individual PFOA/PFOS values, that distinction is exactly the kind of detail worth watching as monitoring ramps up over the next few years.
EPA held a virtual public hearing on July 7, 2026. As of today — July 15, 2026 — the comment dockets remain open through July 20, 2026, five days from now, with more than 15,000 comments already submitted. Nothing here is final yet; treat the 2024 rule as the current baseline until EPA actually finalizes a change, and check back here as the comment period closes.
See the full regulatory timeline for how this fits with the 2020 state standard and the 2024 federal rule.
System-wide data only tells part of the story — service lines, home plumbing, and private wells can all change what actually comes out of your tap.
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