Community Water System · PWS IL0312520
Posen
Operator location Posen, Illinois - larger served population (> 3,309) at 5,331 people served; 57 SDWIS violations on record from surface water sources.
- 5,331
- People served (this PWS) Larger third of systems
- 57
- EPA violations (this PWS) Middle third of systems
- 9
- Health-based (this PWS) Middle third by health-based share
- No PFAS
- UCMR5 (this PWS) Tested, none detected
Posen standing, mid SDWIS violation third
5,331 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 16% is middle-third health share (≤ 23%). UCMR5: UCMR5 tested, none detected. Population rank #7,430 of 29,740 among systems serving 500+.
The verdict
Posen lands in the middle third by violation volume (57), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is large (5,331; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 16% (middle-third health share (≤ 23%)). UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #7,430 of 29,740
- Population · /systems
- #351 of 1,310
- Population · IL
- 57
- Total EPA violations on record
- 16%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
Based on EPA SDWIS violation history and UCMR5 PFAS testing only, not water taste, odor, infrastructure age, or contaminants outside the federally tracked set.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 1,754
- County
- Cook
- School/Daycare
- No
- MCL Violations
- 4
- Monitoring Violations
- 35
- Treatment Tech Violations
- 5
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 22 | 2002 |
| Consumer Confidence Rule | Other | 9 | 2025 |
| Lead and Copper Rule | TT | 5 | 1996 |
| Lead and Copper Rule | MR | 5 | 2020 |
| Coliform (TCR) | MCL | 4 | 2013 |
| LEAD AND COPPER RULE REVISIONS | RPT | 4 | 2025 |
| TTHM | MR | 4 | 2014 |
| Total Haloacetic Acids (HAA5) | MR | 4 | 2014 |
Violation Count vs. the National Corpus
Posen has 57 recorded EPA violations, 60% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 40% carry more. 16% of this system's own violations are health-based (9 of 57), and it ranks #7,430 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)
57 Around the middle fewer violations than 40% 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
How many violations vs. how serious, among peer systems
Posen plotted against 29 peer public water systems (500+ people served), by total violation count (x) and the share of those violations that are health-based (y). The crosshair sits at this sample's own median on each axis. A high violation count does not automatically mean a serious record: most monitoring and reporting violations are minor, not health-based.
Violation volume vs. health-based share
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 116 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| NMeFOSAA | 9/12/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 9/12/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 9/12/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 9/12/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFEESA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| ADONA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 9/12/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 9/12/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 6:2 FTS | 9/12/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 9/12/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 9/12/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 9/12/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 9/12/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 9/12/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| 9Cl-PF3ONS | 9/12/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFBS | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 9/12/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOA | 9/12/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFDA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 9/12/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 9/12/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFPeA | 9/12/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 6/13/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeS | 6/13/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFDA | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 4:2 FTS | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 6/13/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 8:2 FTS | 6/13/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 6/13/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBS | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 6/13/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 6/13/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 6/13/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFMBA | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBA | 6/13/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFOA | 6/13/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 6/13/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 6/13/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 6/13/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 6/13/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
Population served record for Posen
EPA SDWIS lists 5,331 people served and 1,754 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS · Illinois EPA, Bureau of Water
Nationwide peers
57 violations · 5,331 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 Posen
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.
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.