Community Water System · PWS IL0010500
Mendon
Operator location Mendon, Illinois - 35% of 34 violations are health-based (upper-third health share (> 23%)); groundwater source; 953 served per SDWIS.
- 953
- People served (this PWS)
- 34
- EPA violations (this PWS)
- 12
- Health-based (this PWS)
- No PFAS
- UCMR5 (this PWS)
Mendon standing, mid SDWIS violation third
35% of 34 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 35% is upper-third health share (> 23%). UCMR5: UCMR5 tested, none detected. Population rank #20,320 of 29,740 among systems serving 500+.
The verdict
Mendon lands in the middle third by violation volume (34), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is smaller (953; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 35% - most of this ledger is MCL or treatment-technique exceedance. UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #20,320 of 29,740
- Population · /systems
- #907 of 1,310
- Population · IL
- 34
- Total EPA violations on record
- 35%
- 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
- 435
- County
- Adams
- School/Daycare
- No
- MCL Violations
- 12
- Monitoring Violations
- 19
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Nitrate | MCL | 12 | 2010 |
| Coliform (TCR) | MR | 10 | 2004 |
| Nitrate | MR | 4 | 2010 |
| Chlorine | MR | 4 | 2004 |
| Gross Alpha, Excl. Radon and U | MR | 1 | 1977 |
Violation Count vs. the National Corpus
Mendon has 34 recorded EPA violations, 46% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 54% carry more. 35% of this system's own violations are health-based (12 of 34), and it ranks #20,320 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)
34 Lower than most fewer violations than 54% 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 |
|---|---|---|---|---|
| PFUnA | 7/9/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFPeS | 7/9/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 7/9/2025 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFEESA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 7/9/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 7/9/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 7/9/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 7/9/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 7/9/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 7/9/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFDA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 7/9/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 7/9/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 7/9/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 7/9/2025 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 7/9/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 7/9/2025 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 7/9/2025 | <8.00 ppt | 8.00 ppt | Not Detected |
| 9Cl-PF3ONS | 7/9/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFOS | 7/9/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFBA | 1/7/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 1/7/2025 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 1/7/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 1/7/2025 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 1/7/2025 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFHpS | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 1/7/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 1/7/2025 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFEESA | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 1/7/2025 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 1/7/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 6:2 FTS | 1/7/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 1/7/2025 | <5.00 ppt | 5.00 ppt | Not Detected |
| 9Cl-PF3ONS | 1/7/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFUnA | 1/7/2025 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 1/7/2025 | <3.00 ppt | 3.00 ppt | Not Detected |
Health-based violations on Mendon
12 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for IL0010500.
Sources: EPA SDWIS · Illinois EPA, Bureau of Water
Nationwide peers
34 violations · 953 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 smaller service footprints
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Mendon
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Illinois compares on the same EPA violation measures. Illinois 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.