Hingham, Hull, and North Cohasset are served by the Weir River Water System, operated by Aquarion Water Company, reaching an estimated 45,339 residents. Supply comes from two sources: surface water drawn from Accord Brook and Accord Pond, and groundwater pumped from eleven active wells across the Weir Watershed. A portion of the wellfield's protection area extends into neighboring Norwell.
Massachusetts DEP records note that the aquifer feeding these wells has high vulnerability to contamination — there is no confining clay layer to slow the movement of surface contaminants down into the groundwater.
Before reaching taps, water passes through a multi-stage treatment process: lime addition for pH adjustment, potassium permanganate for oxidation, alum-and-polymer coagulation and flocculation, upflow clarification, granular-activated carbon filtration, chlorine disinfection, and fluoridation.
According to EPA's Safe Drinking Water Information System (SDWIS), the Weir River Water System has recorded no health-based Maximum Contaminant Level (MCL) violations since 2010. That means the utility has stayed within its legally required limits for regulated contaminants over that period.
Legal compliance is not the same as zero risk. The EPA sets MCLs based on what's feasible to treat at scale across an entire water system — not necessarily the level with zero associated health risk for every individual.
The EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR5) requires large water systems to test for a rotating list of emerging contaminants that aren't yet subject to enforceable limits — including several PFAS ("forever chemical") compounds. Testing in this round returned detectable levels of five PFAS compounds in the Weir River system:
| Compound | Detected level | EPA individual limit | Status |
|---|---|---|---|
| PFOA | 5.7 ppt | 4 ppt | Above EPA health-based limit |
| PFBA | 5.7 ppt | No individual MCL | Monitored, not yet regulated |
| PFBS | 3.3 ppt | No individual MCL | Monitored, not yet regulated |
| PFPeA | 3.1 ppt | No individual MCL | Monitored, not yet regulated |
| PFHxA | 3.1 ppt | No individual MCL | Monitored, not yet regulated |
ppt = parts per trillion. The EPA's 2024 limit for PFOA and PFOS individually is 4 ppt each; the other listed compounds are monitored under UCMR5 but do not yet carry an individual enforceable limit. Source: EPA UCMR5 occurrence data.
How the rules around PFAS in drinking water have actually changed over the past several years — and where they stand right now.
MassDEP finalized an enforceable Maximum Contaminant Level (MCL) of 20 parts per trillion (ppt) for the sum of six PFAS compounds ("PFAS6") — PFOS, PFOA, PFHxS, PFNA, PFHpA, and PFDA. At the time, Massachusetts was among the first states in the country with a legally enforceable PFAS drinking water standard; there was still no federal one. This is the standard the Weir River Water System is required to meet today.
As detailed above, this nationwide EPA monitoring round is what actually produced the Weir River system's PFOA reading of 5.7 ppt — above the individual federal limit that would be finalized the following year, though there was no enforceable federal PFOA limit yet at the time of testing.
The EPA's National Primary Drinking Water Regulation (NPDWR) set the first-ever enforceable federal limits for PFAS: 4 ppt each for PFOA and PFOS individually, 10 ppt each for PFHxS, PFNA, and HFPO-DA (GenX), plus a combined Hazard Index limit for mixtures of those and PFBS. Water systems were given until 2027 to complete initial monitoring and until 2029 to come into full compliance.
EPA proposed keeping the PFOA and PFOS limits at 4 ppt each, but allowing water systems to request a two-year compliance extension — to 2031 instead of 2029. In a separate proposal, EPA moved to rescind the individual limits for PFHxS, PFNA, and HFPO-DA and the Hazard Index for PFAS mixtures, citing procedural requirements under the Safe Drinking Water Act. The PFOA and PFOS limits themselves were not proposed for rescission. Public comment on these proposals was open through July 20, 2026 — check EPA's site directly for the current status before assuming either proposal is final.
Sources: Mass.gov — Massachusetts PFAS Drinking Water Standard (MCL); Federal Register — PFAS National Primary Drinking Water Regulation (April 2024); EPA — Proposed PFOA and PFOS Compliance Extension Rule; EPA — Proposed PFAS Rescission Rule.
We don't ask you to take our word for any of this. The underlying reports are public:
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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