Community Water System · PWS IL1110600
McHenry
McHenry, Illinois 60050 - drinking water served from groundwater sources to 22,335 people, tracked in EPA SDWIS and UCMR5.
- 22,335
- People served
- 101
- EPA violations
- 4
- Health-based
- 1 PFAS
- UCMR5 result
The verdict
EPA records 101 drinking-water violations at McHenry, 4% of them health-based - above the Illinois per-system average, and UCMR5 testing detected 1 PFAS compound.
- 101
- Total EPA violations on record
- 4%
- Health-based (MCL / treatment failure)
- 22,335
- People served by this system
- 1
- PFAS compounds detected (UCMR5)
Water Quality Snapshot: McHenry
McHenry is a local-owned community water system that delivers drinking water to 22,335 residents in McHenry, Illinois (McHenry County) through 8,484 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 101 total violations for this system , of which 4 (4%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 93 monitoring and reporting violations are on file. The most recent violation on record dates to 2025.
The most frequently cited contaminant at this system is Lead and Copper Rule, recorded in 8 violations (MR). Under EPA's UCMR5 PFAS monitoring program, 1 PFAS compound was detected in samples collected from this system, with a maximum reported concentration of 3.9 ppt (parts per trillion). PFAS are persistent synthetic chemicals linked to health effects at very low exposure levels.
Across Illinois, EPA tracks 5,117 public water systems serving 12,576,876 people, with 355,322 cumulative violations and 52,932 health-based violations on record. About 81% of systems in the state carry at least one violation, and state-wide the average per system is 69.4 violations. Statewide, 199 of 487 UCMR5-tested systems have reported PFAS detections (40.9%).
McHenry's 101 violations sit above the Illinois average.
All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.
1 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 8,484
- County
- McHenry
- School/Daycare
- No
- MCL Violations
- 2
- Monitoring Violations
- 93
- Treatment Tech Violations
- 2
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Lead and Copper Rule | MR | 8 | 2025 |
| Vinyl chloride | MR | 4 | 2023 |
| o-Dichlorobenzene | MR | 4 | 2023 |
| 1,2-Dichloropropane | MR | 4 | 2023 |
| 1,1,2-Trichloroethane | MR | 4 | 2023 |
| Tetrachloroethylene | MR | 4 | 2023 |
| CHLOROBENZENE | MR | 4 | 2023 |
| Toluene | MR | 4 | 2023 |
| DICHLOROMETHANE | MR | 4 | 2023 |
| Xylenes, Total | MR | 4 | 2023 |
| Trichloroethylene | MR | 4 | 2023 |
| 1,1-Dichloroethylene | MR | 4 | 2023 |
| cis-1,2-Dichloroethylene | MR | 4 | 2023 |
| Benzene | MR | 4 | 2023 |
| Carbon tetrachloride | MR | 4 | 2023 |
| 1,2,4-Trichlorobenzene | MR | 4 | 2023 |
| p-Dichlorobenzene | MR | 4 | 2023 |
| Styrene | MR | 4 | 2023 |
| 1,2-Dichloroethane | MR | 4 | 2023 |
| Ethylbenzene | MR | 4 | 2023 |
| trans-1,2-Dichloroethylene | MR | 4 | 2023 |
| 1,1,1-Trichloroethane | MR | 4 | 2023 |
| Coliform (TCR) | MCL | 2 | 1996 |
| Lead and Copper Rule | TT | 2 | 1992 |
| Gross Alpha, Excl. Radon and U | MR | 1 | 1977 |
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 1 of 232 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFTA | 5/23/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| NEtFOSAA | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 5/23/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFTrDA | 5/23/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| 4:2 FTS | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NFDHA | 5/23/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| 8:2 FTS | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFPeA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 5/23/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpS | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTA | 5/23/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFTrDA | 5/23/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| NMeFOSAA | 5/23/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFBA | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMBA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NEtFOSAA | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 5/23/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 5/23/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 5/23/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 5/23/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 5/23/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 5/23/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 5/23/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFPeS | 5/23/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTA | 5/23/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| NMeFOSAA | 5/23/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 5/23/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHpS | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 5/23/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 5/23/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFTrDA | 5/23/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
Verify This Water System
The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for McHenry.
EPA SDWIS, Federal Reports
EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:
View PWS ID IL1110600 on SDWISSource: EPA SDWIS Federal Reports Search
Illinois Drinking Water Authority
Illinois EPA, Bureau of Water is the primacy agency that licenses and inspects McHenry under EPA-delegated authority.
Open IL regulator portalSource: Illinois EPA, Bureau of Water
Violation Timeline
Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.
| Year (latest) | Contaminant | Category | Count | EPA Record |
|---|---|---|---|---|
| 2025 | Lead and Copper Rule | MR | 8 | SDWIS / IL1110600 / 5000 |
| 2023 | Vinyl chloride | MR | 4 | SDWIS / IL1110600 / 2976 |
| 2023 | o-Dichlorobenzene | MR | 4 | SDWIS / IL1110600 / 2968 |
| 2023 | 1,2-Dichloropropane | MR | 4 | SDWIS / IL1110600 / 2983 |
| 2023 | 1,1,2-Trichloroethane | MR | 4 | SDWIS / IL1110600 / 2985 |
| 2023 | Tetrachloroethylene | MR | 4 | SDWIS / IL1110600 / 2987 |
| 2023 | CHLOROBENZENE | MR | 4 | SDWIS / IL1110600 / 2989 |
| 2023 | Toluene | MR | 4 | SDWIS / IL1110600 / 2991 |
| 2023 | DICHLOROMETHANE | MR | 4 | SDWIS / IL1110600 / 2964 |
| 2023 | Xylenes, Total | MR | 4 | SDWIS / IL1110600 / 2955 |
| 2023 | Trichloroethylene | MR | 4 | SDWIS / IL1110600 / 2984 |
| 2023 | 1,1-Dichloroethylene | MR | 4 | SDWIS / IL1110600 / 2977 |
| 2023 | cis-1,2-Dichloroethylene | MR | 4 | SDWIS / IL1110600 / 2380 |
| 2023 | Benzene | MR | 4 | SDWIS / IL1110600 / 2990 |
| 2023 | Carbon tetrachloride | MR | 4 | SDWIS / IL1110600 / 2982 |
How McHenry Compares
Cross-reference this system's record against state averages and the federal MCL framework for context.
| Metric | McHenry | Illinois avg | Federal benchmark |
|---|---|---|---|
| Total violations | 101 | 69.4 | SDWA compliance, any non-zero count is a recorded breach |
| Health-based violations | 4 | 10.3 | Indicates a contaminant exceeded a federal MCL |
| PFAS detection | 1 compound | 40.9% | EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt |
| Population served | 22,335 | 2,458 | Sizing context for compliance burden |
Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 5,117 regulated public water systems in Illinois.
Federal MCL reference, Safe Drinking Water Act thresholds ▼
| Contaminant | Federal MCL / Action Level | Note |
|---|---|---|
| Lead | 0 mg/L (Action Level: 0.015 mg/L) | Lead and Copper Rule treatment technique |
| Arsenic | 0.010 mg/L (10 ppb) | Health-based MCL since 2006 |
| Total Coliform | Treatment technique (RTCR) | Indicator organism, monitoring trigger |
| PFOA / PFOS (PFAS) | 4.0 ppt each (final 2024 rule) | Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026) |
| Nitrate (as N) | 10 mg/L | Acute health risk for infants |
Frequently Asked Questions
Is McHenry water safe to drink? ▼
How many people does McHenry serve? ▼
What type of violations does McHenry have? ▼
Has PFAS been detected in McHenry water? ▼
What water source does McHenry use? ▼
Where does this data come from? ▼
Read our methodology - how this data is sourced, computed, and verified.
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.