ONSET FIRE DISTRICTWATER DEPT.
PWS ID: MA4310003 · ONSET, Massachusetts 02558
PFAS Detected
1 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
Population Served
5,392
Total Violations
72
Health-Based Violations
16
Water Source
Groundwater
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 2,982
- County
- Plymouth
- School/Daycare
- No
- MCL Violations
- 16
- Monitoring Violations
- 39
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 15 | 2013 |
| Lead and Copper Rule | MR | 6 | 2019 |
| Coliform (TCR) | MR | 3 | 2013 |
| Consumer Confidence Rule | Other | 2 | 2022 |
| Coliform (TCR) | Other | 2 | 2011 |
| Revised Total Coliform Rule | MCL | 1 | 2019 |
| Toxaphene | MR | 1 | 1991 |
| Methoxychlor | MR | 1 | 1991 |
| Endrin | MR | 1 | 1991 |
| Nitrate | MR | 1 | 1997 |
| 1,2-Dichloroethane | MR | 1 | 2020 |
| 1,1,2-Trichloroethane | MR | 1 | 2020 |
| Vinyl chloride | MR | 1 | 2020 |
| Ethylbenzene | MR | 1 | 2020 |
| 1,2,4-Trichlorobenzene | MR | 1 | 2020 |
| cis-1,2-Dichloroethylene | MR | 1 | 2020 |
| o-Dichlorobenzene | MR | 1 | 2020 |
| Trichloroethylene | MR | 1 | 2020 |
| Carbon tetrachloride | MR | 1 | 2020 |
| 1,1,1-Trichloroethane | MR | 1 | 2020 |
| CHLOROBENZENE | MR | 1 | 2020 |
| trans-1,2-Dichloroethylene | MR | 1 | 2020 |
| Benzene | MR | 1 | 2020 |
| 1,2-DIBROMO-3-CHLOROPROPANE | MR | 1 | 2020 |
| Toluene | MR | 1 | 2020 |
| 1,2-Dichloropropane | MR | 1 | 2020 |
| p-Dichlorobenzene | MR | 1 | 2020 |
| Styrene | MR | 1 | 2020 |
| DICHLOROMETHANE | MR | 1 | 2020 |
| ETHYLENE DIBROMIDE | MR | 1 | 2020 |
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 1 of 120 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFPeA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFBS | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| NMeFOSAA | 6/24/2025 | <0.006 µg/L | 0.006 µg/L | Not Detected |
| 8:2 FTS | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| NEtFOSAA | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFTrDA | 6/24/2025 | <0.007 µg/L | 0.007 µg/L | Not Detected |
| PFTA | 6/24/2025 | <0.008 µg/L | 0.008 µg/L | Not Detected |
| PFMPA | 6/24/2025 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFNA | 6/24/2025 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFMBA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFEESA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| NFDHA | 6/24/2025 | <0.02 µg/L | 0.02 µg/L | Not Detected |
| PFPeS | 6/24/2025 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFHpS | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| lithium | 6/24/2025 | <9 µg/L | 9 µg/L | Not Detected |
| 11Cl-PF3OUdS | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| 4:2 FTS | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 6:2 FTS | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFBA | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| HFPO-DA | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFHpA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 9Cl-PF3ONS | 6/24/2025 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| PFHxS | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFUnA | 6/24/2025 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| PFHxA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFDoA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFDA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFOA | 6/24/2025 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFOS | 6/24/2025 | 0.0071 µg/L | 0.004 µg/L | Detected |
| ADONA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFUnA | 6/24/2025 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| PFBA | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| lithium | 6/24/2025 | <9 µg/L | 9 µg/L | Not Detected |
| NMeFOSAA | 6/24/2025 | <0.006 µg/L | 0.006 µg/L | Not Detected |
| NEtFOSAA | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFTrDA | 6/24/2025 | <0.007 µg/L | 0.007 µg/L | Not Detected |
| PFTA | 6/24/2025 | <0.008 µg/L | 0.008 µg/L | Not Detected |
| PFHpS | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFPeS | 6/24/2025 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFMBA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFPeA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFMPA | 6/24/2025 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| 8:2 FTS | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFDoA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 6:2 FTS | 6/24/2025 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFOA | 6/24/2025 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| NFDHA | 6/24/2025 | <0.02 µg/L | 0.02 µg/L | Not Detected |
| PFBS | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFHpA | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFHxS | 6/24/2025 | <0.003 µg/L | 0.003 µg/L | Not Detected |
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025.
PFAS data from EPA UCMR5 monitoring program (2023-2025).
This data is provided for informational purposes only.