Community Water System · PWS IL0950450
Rio
Operator location Rio, Illinois - smaller served population (≤ 999) at 265 people served; 165 SDWIS violations on record from groundwater sources.
- 265
- People served (this PWS)
- 165
- EPA violations (this PWS)
- 15
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Rio standing, high SDWIS violation third
265 people served (SDWIS) - smaller served population (≤ 999). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 9% is middle-third health share (≤ 23%).
The verdict
Rio sits in the upper third of the sitemap cohort by violation count (165), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (265; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 9% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- 165
- Total EPA violations on record
- 9%
- Health-based (MCL / treatment failure)
- 265
- People served by this PWS (SDWIS)
- N/A
- PFAS compounds detected (UCMR5)
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
- 106
- County
- Knox
- School/Daycare
- No
- MCL Violations
- 15
- Monitoring Violations
- 121
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 26 | 2008 |
| Fluoride | MCL | 15 | 1984 |
| Arsenic | MR | 4 | 1986 |
| Cadmium | MR | 4 | 1986 |
| Fluoride | MR | 4 | 1986 |
| Nitrate | MR | 4 | 1986 |
| Selenium | MR | 4 | 1986 |
| Barium | MR | 4 | 1986 |
| Mercury | MR | 4 | 1986 |
| Chromium | MR | 4 | 1986 |
| cis-1,2-Dichloroethylene | MR | 3 | 1994 |
| Xylenes, Total | MR | 3 | 1994 |
| o-Dichlorobenzene | MR | 3 | 1994 |
| 1,2-Dichloropropane | MR | 3 | 1994 |
| Tetrachloroethylene | MR | 3 | 1994 |
| Toluene | MR | 3 | 1994 |
| Ethylbenzene | MR | 3 | 1994 |
| 1,2,4-Trichlorobenzene | MR | 3 | 1994 |
| 1,1,2-Trichloroethane | MR | 3 | 1994 |
| 1,2-Dichloroethane | MR | 3 | 1994 |
| trans-1,2-Dichloroethylene | MR | 3 | 1994 |
| DICHLOROMETHANE | MR | 3 | 1994 |
| 1,1-Dichloroethylene | MR | 3 | 1994 |
| p-Dichlorobenzene | MR | 3 | 1994 |
| CHLOROBENZENE | MR | 3 | 1994 |
| Carbon tetrachloride | MR | 3 | 1994 |
| Trichloroethylene | MR | 3 | 1994 |
| Styrene | MR | 3 | 1994 |
| 1,1,1-Trichloroethane | MR | 3 | 1994 |
| Benzene | MR | 3 | 1994 |
Violation Count vs. the National Corpus
Rio has 165 recorded EPA violations, 82% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 17% carry more. 9% of this system's own violations are health-based (15 of 165), and it ranks unranked by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
165 Higher than most more violations than 82% 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
Population served record for Rio
EPA SDWIS lists 265 people served and 106 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
165 violations · 265 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.
What to do with Rio
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.