Every Massachusetts public water system that reported a PFAS detection during EPA UCMR 5 monitoring, how many sit above the 2024 federal limits, and the standard Massachusetts applies. Concentrations are in nanograms per litre, the same unit as parts per trillion.
This is the United States view of the North American PFAS dataset. The complete dataset, including all 3,452 US systems and 97 Canadian sites, lives on the main PFAS contamination map.
State enforceable standard
Among the strictest US enforceable MCLs; extensive PWS compliance sampling since 2021.
Compound
Limit (ng/L)
Note
Sum of 6 PFAS (PFOA, PFOS, PFHxS, PFNA, PFHpA, PFDA)
20
Enforceable MCL
US EPA PFAS National Primary Drinking Water Regulation (2024)
Last reviewed 2026-08-13. Verify against the agency source before making a compliance or remediation decision.
Full Massachusetts regulatory brief
Ranked by how far the worst single compound sits above its 2024 federal limit. Values are the maximum each system reported during its UCMR 5 monitoring period.
Water system
PWSID
Worst compound
Max ng/L
Times the limit
Raynham Center Water District
MA4245000
PFOA
92
23.0x
Dartmouth Water Division
MA4072000
PFOS
50.6
12.7x
Natick Water Department
MA3198000
PFOS
37.3
9.3x
Duxbury Water Department
MA4082000
PFOS
35
8.8x
Norwell Water Department
MA4219000
PFOS
18.4
4.6x
Easton Water Div
MA4088000
PFOS
16.3
4.1x
Aquarion Water Company, Millbury
MA2186000
PFOA
15.8
4.0x
Sharon Water Dept
MA4266000
PFOS
15
3.8x
Acton Water Supply District
MA2002000
PFOA
13.4
3.4x
Randolph Water Department
MA4244000
PFOS
13
3.3x
Manchester By The Sea Dpw
MA3166000
PFOA
12
3.0x
Abington/Rockland Joint Wtr. Works
MA4001000
PFOA
12
3.0x
Attleboro Water Dept
MA4016000
PFOS
12
3.0x
Holbrook Public Works Dept
MA4133000
PFOS
11.9
3.0x
Pepperell Dpw Water Division
MA2232000
PFOA
11.4
2.9x
Hanover Water Dept, Ma
MA4122000
PFOS
11.4
2.9x
Hamilton Water Dept
MA3119000
PFOS
11.2
2.8x
Middleborough Water Supply
MA4182000
PFOA
11
2.8x
Sudbury Water District
MA3288000
PFOA
9
2.3x
Topsfield Water Department
MA3298000
PFOA
9
2.3x
Open the full map and filter Massachusetts pins
Every count above is read straight from a published government file. Nothing is modelled, averaged, or estimated. The rules below are the exact rules used to produce the figures for Massachusetts.
Who is in UCMR 5. All public water systems serving more than 3,300 people, plus a national sample of 800 smaller systems. Private wells and most small systems are not monitored, so they cannot appear here.
Which systems are listed. Only systems whose state field is MA and that reported at least one measured PFAS detection. Systems that monitored and found nothing are not shown, and their absence is not evidence of contamination. That gives 141 systems in Massachusetts.
Systems that cannot be placed. 87 systems nationally reported a detection but have no serviced ZIP code published by EPA, so they carry no location and are excluded from these counts. National totals on the map page include them.
Which value is used. The highest result a system reported for each compound across its sampling events. Results flagged by EPA as non-detects are excluded, as are the lithium results carried in the same file.
The above a limit count. A system is counted when its maximum result for a compound exceeds the 2024 federal Maximum Contaminant Level: 4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS, PFNA, and HFPO-DA. That is 104 systems in Massachusetts.
The Hazard Index count. Calculated with EPA's own mixture method for PFHxS, PFNA, HFPO-DA, and PFBS. A system is counted when the index is above 1. That is 3 systems in Massachusetts.
What monitoring data is not. Exceeding a 2024 limit in this dataset is not a compliance violation. The federal limits carry a 2029 compliance date, which EPA proposed on 18 May 2026 to move to 2031 for PFOA and PFOS in a rule that is not final, and treatment may have been installed since the sample was taken.
If any figure on this page does not match its source file, tell Nelson and it will be corrected or removed.
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