Community Water System · PWS IL1090200
Colchester
Operator location Colchester, Illinois - 73% of 172 violations are health-based (upper-third health share (> 23%)); surface water source; 1,395 served per SDWIS.
- 1,395
- People served (this PWS)
- 172
- EPA violations (this PWS)
- 125
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Colchester standing, high SDWIS violation third
73% of 172 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 73% is upper-third health share (> 23%). Population rank #16,640 of 29,740 among systems serving 500+.
The verdict
Colchester sits in the upper third of the sitemap cohort by violation count (172), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is mid-pack at 1,395 (mid served population (≤ 3,309)). Health-based share is 73% - most of this ledger is MCL or treatment-technique exceedance. No UCMR5 PFAS test appears for this system in this extract.
- #16,640 of 29,740
- Population · /systems
- #728 of 1,310
- Population · IL
- 172
- Total EPA violations on record
- 73%
- 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
- 620
- County
- McDonough
- School/Daycare
- No
- MCL Violations
- 76
- Monitoring Violations
- 21
- Treatment Tech Violations
- 49
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Combined Radium (-226 and -228) | MCL | 60 | 2005 |
| Interim Enhanced Surface Water Treatment Rule | TT | 49 | 2008 |
| Coliform (TCR) | MR | 16 | 2009 |
| Gross Alpha, Excl. Radon and U | MCL | 12 | 2005 |
| Combined Radium (-226 and -228) | MR | 4 | 2003 |
| Coliform (TCR) | MCL | 4 | 2005 |
| Public Notice | Other | 2 | 2008 |
| Gross Alpha, Excl. Radon and U | MR | 1 | 1977 |
Violation Count vs. the National Corpus
Colchester has 172 recorded EPA violations, 83% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 17% carry more. 73% of this system's own violations are health-based (125 of 172), and it ranks #16,640 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)
172 Higher than most more violations than 83% 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
Health-based violations on Colchester
125 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for IL1090200.
Sources: EPA SDWIS · Illinois EPA, Bureau of Water
Nationwide peers
172 violations · 1,395 served: nearest cross-state SDWIS matches.
Cross-state systems with comparable violation load
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems near this population served
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Colchester
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.