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Updated 2026-10-15
County water report

Lake County Water Quality: 17 Cities Ranked by the Records

Lake County, Illinois: 17 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my systemOpen on the mapPrivate wells in Lake County
Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

LithiumDetected in 4 systems of 17 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest43.3 µg/L
  • ZION43.3 µg/LSample date: 2025-01-27 to 2025-10-21
  • LAKE ZURICH26 µg/LSample date: 2023-06-20 to 2024-09-23
  • ANTIOCH13.4 µg/LSample date: 2024-11-20 to 2025-05-15
  • FOX LAKE10.6 µg/LSample date: 2024-02-27 to 2024-08-12
  • BUFFALO GROVENot detected · below 9.0 µg/L lab reporting limitSample date: 2024-10-15 to 2025-07-08
  • DEERFIELDNot detected · below 9.0 µg/L lab reporting limitSample date: 2024-02-22 to 2024-11-05
  • GRAYSLAKENot detected · below 9.0 µg/L lab reporting limitSample date: 2023-03-28 to 2023-12-11
  • GURNEENot detected · below 9.0 µg/L lab reporting limitSample date: 2024-04-09 to 2025-01-07
  • HIGHLAND PARKNot detected · below 9.0 µg/L lab reporting limitSample date: 2024-05-08 to 2025-02-03
  • LAKE FORESTNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-08-21 to 2024-05-06
  • LIBERTYVILLENot detected · below 9.0 µg/L lab reporting limitSample date: 2023-05-31 to 2024-02-21
  • MUNDELEINNot detected · below 9.0 µg/L lab reporting limitSample date: 2024-04-17 to 2025-01-06
  • NORTH CHICAGONot detected · below 9.0 µg/L lab reporting limitSample date: 2025-02-25 to 2025-11-11
  • ROUND LAKENot detected · below 9.0 µg/L lab reporting limitSample date: 2025-05-13 to 2026-02-18
  • VERNON HILLS - LAKE CO PWNot detected · below 9.0 µg/L lab reporting limitSample date: 2024-06-26 to 2025-03-05
  • WAUCONDANot detected · below 9.0 µg/L lab reporting limitSample date: 2024-08-06 to 2025-05-14
  • WAUKEGANNot detected · below 9.0 µg/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
Lead (90th percentile)Detected in 14 systems of 17 tested15 µg/L federal action level · US EPAHighest21 µg/L
  • LAKE FOREST21 µg/LMonitoring period: 2026–2026 (still open)
  • ZION11.2 µg/LMonitoring period: 2026–2026 (still open)
  • GRAYSLAKE11 µg/LMonitoring period: 2026–2026 (still open)
  • WAUKEGAN10 µg/LMonitoring period: 2026–2026 (still open)
  • WAUCONDA9.6 µg/LMonitoring period: 2026–2026 (still open)
  • ANTIOCH7.2 µg/LMonitoring period: 2026–2026 (still open)
  • LIBERTYVILLE5.61 µg/LMonitoring period: 2026–2026 (still open)
  • DEERFIELD4.8 µg/LMonitoring period: 2026–2026 (still open)
  • MUNDELEIN4.3 µg/LMonitoring period: 2026–2026 (still open)
  • NORTH CHICAGO3.6 µg/LMonitoring period: 2026–2026 (still open)
  • FOX LAKE3.2 µg/LMonitoring period: 2026–2026 (still open)
  • LAKE ZURICH2.74 µg/LMonitoring period: 2025–2025
  • ROUND LAKE2.7 µg/LMonitoring period: 2026–2026 (still open)
  • BUFFALO GROVE1.3 µg/LMonitoring period: 2024–2026 (still open)
  • GURNEENot detectedMonitoring period: 2025–2025
  • HIGHLAND PARKNot detectedMonitoring period: 2025–2025
  • VERNON HILLS - LAKE CO PWNot detectedMonitoring period: 2021–2023
Perfluorooctanesulfonic acid (PFOS)Detected in 1 system of 17 tested4.0 ng/L federal MCL (2024) · US EPAHighest5 ng/L
  • FOX LAKE5 ng/LSample date: 2024-02-27 to 2024-08-12
  • ANTIOCHNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-11-20 to 2025-05-15
  • BUFFALO GROVENot detected · below 4.0 ng/L lab reporting limitSample date: 2024-10-15 to 2025-07-08
  • DEERFIELDNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-02-22 to 2024-11-05
  • GRAYSLAKENot detected · below 4.0 ng/L lab reporting limitSample date: 2023-03-28 to 2023-12-11
  • GURNEENot detected · below 4.0 ng/L lab reporting limitSample date: 2024-04-09 to 2025-01-07
  • HIGHLAND PARKNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-05-08 to 2025-02-03
  • LAKE FORESTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-08-21 to 2024-05-06
  • LAKE ZURICHNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-06-20 to 2024-09-20
  • LIBERTYVILLENot detected · below 4.0 ng/L lab reporting limitSample date: 2023-05-31 to 2024-02-21
  • MUNDELEINNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-04-17 to 2025-01-06
  • NORTH CHICAGONot detected · below 4.0 ng/L lab reporting limitSample date: 2025-02-25 to 2025-11-11
  • ROUND LAKENot detected · below 4.0 ng/L lab reporting limitSample date: 2025-05-13 to 2026-02-18
  • VERNON HILLS - LAKE CO PWNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-06-26 to 2025-03-05
  • WAUCONDANot detected · below 4.0 ng/L lab reporting limitSample date: 2024-08-06 to 2025-05-14
  • WAUKEGANNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • ZIONNot detected · below 4.0 ng/L lab reporting limitSample date: 2025-01-27 to 2025-10-21
Copper (90th percentile)Detected in 1 system1.3 mg/L federal action level · US EPAHighest1.58 mg/L
  • FOX LAKE1.58 mg/LMonitoring period: 2025–2025
Perfluorohexanoic acid (PFHxA)Detected in 1 system of 17 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest3.5 ng/L
  • LAKE ZURICH3.5 ng/LSample date: 2023-06-20 to 2024-09-20
  • ANTIOCHNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-11-20 to 2025-05-15
  • BUFFALO GROVENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-10-15 to 2025-07-08
  • DEERFIELDNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-02-22 to 2024-11-05
  • FOX LAKENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-02-27 to 2024-08-12
  • GRAYSLAKENot detected · below 3.0 ng/L lab reporting limitSample date: 2023-03-28 to 2023-12-11
  • GURNEENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-09 to 2025-01-07
  • HIGHLAND PARKNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-05-08 to 2025-02-03
  • LAKE FORESTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-08-21 to 2024-05-06
  • LIBERTYVILLENot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-31 to 2024-02-21
  • MUNDELEINNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-17 to 2025-01-06
  • NORTH CHICAGONot detected · below 3.0 ng/L lab reporting limitSample date: 2025-02-25 to 2025-11-11
  • ROUND LAKENot detected · below 3.0 ng/L lab reporting limitSample date: 2025-05-13 to 2026-02-18
  • VERNON HILLS - LAKE CO PWNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-06-26 to 2025-03-05
  • WAUCONDANot detected · below 3.0 ng/L lab reporting limitSample date: 2024-08-06 to 2025-05-14
  • WAUKEGANNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • ZIONNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-01-27 to 2025-10-21
Perfluorobutanoic acid (PFBA)Detected in 1 system of 17 testedNo federal or state limit; shown for transparencyHighest5.1 ng/L
  • LIBERTYVILLE5.1 ng/LSample date: 2023-05-31 to 2024-02-21
  • ANTIOCHNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-11-20 to 2025-05-15
  • BUFFALO GROVENot detected · below 5.0 ng/L lab reporting limitSample date: 2024-10-15 to 2025-07-08
  • DEERFIELDNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-02-22 to 2024-11-05
  • FOX LAKENot detected · below 5.0 ng/L lab reporting limitSample date: 2024-02-27 to 2024-08-12
  • GRAYSLAKENot detected · below 5.0 ng/L lab reporting limitSample date: 2023-03-28 to 2023-12-11
  • GURNEENot detected · below 5.0 ng/L lab reporting limitSample date: 2024-04-09 to 2025-01-07
  • HIGHLAND PARKNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-05-08 to 2025-02-03
  • LAKE FORESTNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-08-21 to 2024-05-06
  • LAKE ZURICHNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-06-20 to 2024-09-20
  • MUNDELEINNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-04-17 to 2025-01-06
  • NORTH CHICAGONot detected · below 5.0 ng/L lab reporting limitSample date: 2025-02-25 to 2025-11-11
  • ROUND LAKENot detected · below 5.0 ng/L lab reporting limitSample date: 2025-05-13 to 2026-02-18
  • VERNON HILLS - LAKE CO PWNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-06-26 to 2025-03-05
  • WAUCONDANot detected · below 5.0 ng/L lab reporting limitSample date: 2024-08-06 to 2025-05-14
  • WAUKEGANNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • ZIONNot detected · below 5.0 ng/L lab reporting limitSample date: 2025-01-27 to 2025-10-21
Perfluoropentanoic acid (PFPeA)Detected in 2 systems of 17 testedNo federal or state limit; shown for transparencyHighest3.5 ng/L
  • FOX LAKE3.5 ng/LSample date: 2024-02-27 to 2024-08-12
  • LAKE ZURICH3.5 ng/LSample date: 2023-06-20 to 2024-09-20
  • ANTIOCHNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-11-20 to 2025-05-15
  • BUFFALO GROVENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-10-15 to 2025-07-08
  • DEERFIELDNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-02-22 to 2024-11-05
  • GRAYSLAKENot detected · below 3.0 ng/L lab reporting limitSample date: 2023-03-28 to 2023-12-11
  • GURNEENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-09 to 2025-01-07
  • HIGHLAND PARKNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-05-08 to 2025-02-03
  • LAKE FORESTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-08-21 to 2024-05-06
  • LIBERTYVILLENot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-31 to 2024-02-21
  • MUNDELEINNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-17 to 2025-01-06
  • NORTH CHICAGONot detected · below 3.0 ng/L lab reporting limitSample date: 2025-02-25 to 2025-11-11
  • ROUND LAKENot detected · below 3.0 ng/L lab reporting limitSample date: 2025-05-13 to 2026-02-18
  • VERNON HILLS - LAKE CO PWNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-06-26 to 2025-03-05
  • WAUCONDANot detected · below 3.0 ng/L lab reporting limitSample date: 2024-08-06 to 2025-05-14
  • WAUKEGANNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • ZIONNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-01-27 to 2025-10-21
25 PFAS tested, none detected in any systemShow

Tested in these 17 systems: ANTIOCH, BUFFALO GROVE, DEERFIELD, FOX LAKE, GRAYSLAKE, GURNEE, HIGHLAND PARK, LAKE FOREST, LAKE ZURICH, LIBERTYVILLE, MUNDELEIN, NORTH CHICAGO, ROUND LAKE, VERNON HILLS - LAKE CO PW, WAUCONDA, WAUKEGAN, ZION

  • 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
  • 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
  • 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
  • 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
  • Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
  • N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
  • N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
  • Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
  • Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
  • Perfluoro-3-methoxypropanoic acid (PFMPA)
  • Perfluoro-4-methoxybutanoic acid (PFMBA)
  • Perfluorobutanesulfonic acid (PFBS)
  • Perfluorodecanoic acid (PFDA)
  • Perfluorododecanoic acid (PFDoA)
  • Perfluoroheptanesulfonic acid (PFHpS)
  • Perfluoroheptanoic acid (PFHpA)
  • Perfluorohexanesulfonic acid (PFHxS)
  • Perfluorononanoic acid (PFNA)
  • Perfluorooctanoic acid (PFOA)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
17 cities

Cities ranked by the records

Showing 6 of 17 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.

PFAS in Lake County1 of 17 city reports had a PFAS sample above a 2024 EPA limit
  1. Fox Lake5 ng/L
4.0 ng/L federal MCL · PFOS, ng/LPFAS in Illinois
Lead

1of 17 cities above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in Illinois
Who supplies the county

Largest water systems

  1. WaukeganWAUKEGAN · IL0971900
    87,149 served
  2. Buffalo GroveBUFFALO GROVE · IL0314180
    43,212 served
  3. Vernon HillsVERNON HILLS - LAKE CO PW · IL0971750
    33,207 served
  4. MundeleinMUNDELEIN · IL0971150
    31,500 served
  5. GurneeGURNEE · IL0970350
    30,193 served
  6. Highland ParkHIGHLAND PARK · IL0970500
    30,176 served
  7. ZionZION · IL0972000
    24,442 served
  8. GrayslakeGRAYSLAKE · IL0970250
    21,248 served
  9. LibertyvilleLIBERTYVILLE · IL0970900
    20,500 served
  10. Lake ZurichLAKE ZURICH · IL0970850
    19,759 served
Questions

Frequently asked

How does Lake County tap water compare across cities?

PurityMap ranks 17 cities in Lake County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Vernon Hills's main water system: VERNON HILLS - LAKE CO PW · PWSID IL0971750 · Purity Score 100 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Lake County cities had a PFAS sample above a 2024 EPA limit?

1 of 17 Lake County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Fox Lake (PFOS 5 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 3.

Is there lead in Lake County tap water?

Utilities report lead as a 90th-percentile result from home taps. 14 of 17 Lake County cities reported a value above zero, and 1 city was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

Have Lake County water systems had drinking-water violations?

1 city in Lake County has a health-based violation in the federal SDWIS record within about the last ten years. Each city report lists the contaminant, year and whether it was resolved.

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