Community Water System · PWS MI0007120
Williamston, City Of
Operator location Williamston, Michigan - larger served population (> 3,309) at 3,917 people served; 22 SDWIS violations on record from groundwater sources.
- 3,917
- People served (this PWS)
- 22
- EPA violations (this PWS)
- 4
- Health-based (this PWS)
- No PFAS
- UCMR5 (this PWS)
Williamston, City Of standing, mid SDWIS violation third
3,917 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 18% is middle-third health share (≤ 23%). UCMR5: UCMR5 tested, none detected. Population rank #8,990 of 29,740 among systems serving 500+.
The verdict
Williamston, City Of lands in the middle third by violation volume (22), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is large (3,917; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 18% (middle-third health share (≤ 23%)). UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #8,990 of 29,740
- Population · /systems
- #266 of 1,375
- Population · MI
- 22
- Total EPA violations on record
- 18%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 1,590
- County
- Ingham
- School/Daycare
- No
- MCL Violations
- 4
- Monitoring Violations
- 16
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| TTHM | MR | 8 | 2019 |
| Total Haloacetic Acids (HAA5) | MR | 8 | 2019 |
| Combined Radium (-226 and -228) | MCL | 4 | 2008 |
Violation Count vs. the National Corpus
Williamston, City Of has 22 recorded EPA violations, 34% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 65% carry more. 18% of this system's own violations are health-based (4 of 22), and it ranks #8,990 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
22 Lower than most fewer violations than 65% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 58 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFTA | 9/17/2025 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFDoA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 9/17/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 9/17/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 9/17/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTrDA | 9/17/2025 | <7.00 ppt | 7.00 ppt | Not Detected |
| NEtFOSAA | 9/17/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 9/17/2025 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFBS | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 9/17/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 9/17/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFPeS | 9/17/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 9/17/2025 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFMBA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 9/17/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| ADONA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 9/17/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFEESA | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 9/17/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| HFPO-DA | 9/17/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 9/17/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 9/17/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 9/17/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHxS | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 3/12/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 3/12/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 3/12/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 3/12/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpA | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 3/12/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFEESA | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOS | 3/12/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| ADONA | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 3/12/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 3/12/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 6:2 FTS | 3/12/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 3/12/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 3/12/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFMBA | 3/12/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
Population served record for Williamston, City Of
EPA SDWIS lists 3,917 people served and 1,590 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS · Michigan EGLE, Drinking Water and Environmental Health Division
Nationwide peers
22 violations · 3,917 served: nearest cross-state SDWIS matches.
Cross-state systems near this violation count
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Williamston, City Of
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Michigan compares on the same EPA violation measures. Michigan systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.