ST CHARLES COUNTY PWSD 2
PWS ID: MO6024530 · O FALLON, Missouri 63368-0000
PFAS Detected
2 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
Population Served
100,587
Total Violations
18
Health-Based Violations
9
Water Source
Surface Water
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 38,950
- County
- St. Charles
- School/Daycare
- No
- MCL Violations
- 9
- Monitoring Violations
- 8
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 9 | 2007 |
| Groundwater Rule | MR | 4 | 2025 |
| Revised Total Coliform Rule | MON | 4 | 2021 |
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 11 of 270 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFMPA | 7/16/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFPeA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFMBA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFEESA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| NFDHA | 7/16/2024 | <0.02 µg/L | 0.02 µg/L | Not Detected |
| PFPeS | 7/16/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFHpS | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 8:2 FTS | 7/16/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFHxA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFOS | 7/16/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFHpA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFDoA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFOA | 7/16/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFHxS | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFNA | 7/16/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| 4:2 FTS | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 11Cl-PF3OUdS | 7/16/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFBS | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 9Cl-PF3ONS | 7/16/2024 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| ADONA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| HFPO-DA | 7/16/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFBA | 7/16/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFUnA | 7/16/2024 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| PFDA | 7/16/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 6:2 FTS | 7/16/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFHpA | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFUnA | 6/25/2024 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| PFHxA | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFDoA | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFDA | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFOA | 6/25/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFOS | 6/25/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| 11Cl-PF3OUdS | 6/25/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFHxS | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFBA | 6/25/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFBS | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| NMeFOSAA | 6/25/2024 | <0.006 µg/L | 0.006 µg/L | Not Detected |
| NEtFOSAA | 6/25/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFNA | 6/25/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| 9Cl-PF3ONS | 6/25/2024 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| PFTrDA | 6/25/2024 | <0.007 µg/L | 0.007 µg/L | Not Detected |
| HFPO-DA | 6/25/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFTA | 6/25/2024 | <0.008 µg/L | 0.008 µg/L | Not Detected |
| 6:2 FTS | 6/25/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| 4:2 FTS | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 8:2 FTS | 6/25/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFMPA | 6/25/2024 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFPeA | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFMBA | 6/25/2024 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFEESA | 6/25/2024 | <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.