States › Illinois › Lake County

Lake County, IL Water Quality

Water quality data for 40 public water systems serving Lake County, Illinois — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 40 water systems · 56 cities
✅
Generally Safe — Most Systems Performing Well

The majority of water systems have no active violations and lead levels well below the federal action level.

B

Lake County Earns a B

Lake County: 56 communities across 40 water systems. 96.4% have no open violations.

  • Median lead where detected: 6.29 ppb
  • 28 communities with a lead detection, 28 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 38 with significant inspection deficiencies
  • 96.4% of communities have no open violations
6.29 ppb
Median Lead Level
County-wide, 90th percentile
40
Water Systems
Active CWS & NTNCWS
96%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Third Lake
    Not detected
    No federal limits exceeded on record
    A
  • Gurnee
    Not detected
    No federal limits exceeded on record
    A
  • Libertyville
    Not detected
    No federal limits exceeded on record
    A
  • Round Lake
    2.50 ppb
    No federal limits exceeded on record
    B
  • Lake Villa
    Not detected
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Round Lake Park
    1.40 ppb
    1 violation currently open
    D
  • Green Oaks
    Not detected
    1 violation currently open
    D
  • Lake Forest
    28.00 ppb
    Lead above the 15 ppb action level
    C
  • Highwood
    76.00 ppb
    Lead above the 15 ppb action level
    C
  • Bannockburn
    28.00 ppb
    Lead above the 15 ppb action level
    C
County Lead Level — Median 6.29 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 6.29 ppb — 41.9% of the federal action level
Systems by Lead Level
Under 5 ppb
10
5 – 10 ppb
14
10 – 15 ppb
4
No Data
28

All Cities in Lake County

Waukegan Not detected A
Buffalo Grove Not detected A
Mundelein Not detected A
Gurnee Not detected A
North Chicago Not detected B
Round Lake Beach Not detected B
Highland Park 11.00 ppb B
Vernon Hills Not detected A
Zion 9.10 ppb B
Libertyville Not detected A
Grayslake 2.00 ppb A
Lake Zurich 6.88 ppb A
Lake Forest 28.00 ppb C
Round Lake 2.50 ppb B
Deerfield 5.20 ppb B
Lindenhurst 1.20 ppb A
Wauconda 9.60 ppb B
Antioch 9.00 ppb A
Fox Lake Not detected A
Lake Villa Not detected A
Lincolnshire Not detected A
Beach Park Not detected B
Volo Not detected A
Winthrop Harbor 5.70 ppb C
Gages Lake 1.25 ppb A
Lake Bluff 5.60 ppb B
Round Lake Park 1.40 ppb D
Grandwood Park 1.14 ppb A
Highwood 76.00 ppb C
Lakemoor Not detected B
Green Oaks Not detected D
Kildeer 6.88 ppb A
Hawthorn Woods 1.70 ppb B
Park City Not detected B
Hainesville Not detected B
Round Lake Heights 1.40 ppb B
Long Grove Not detected A
Lake Barrington Not detected B
Knollwood 5.60 ppb B
Riverwoods 2.50 ppb A
Fox Lake Hills Not detected B
Deer Park 6.88 ppb A
Forest Lake 6.88 ppb A
Long Lake Not detected B
North Barrington 6.88 ppb A
Tower Lakes Not detected B
Wadsworth Not detected A
Port Barrington Not detected B
Lake Catherine 9.00 ppb A
Indian Creek Not detected A
Venetian Village Not detected B
Bannockburn 28.00 ppb C
Old Mill Creek 1.20 ppb A
Mettawa Not detected C
Channel Lake 9.00 ppb A
Third Lake Not detected A
Showing 56 cities
No active violations Active violations

About Lake County Drinking Water

Lake County is served by 40 water systems covering 56 communities. 96% have no open violations.

Of the communities reporting lead results, 28 recorded a detection, with a median of 6.29 ppb — 42% of the federal action level. 28 reported none detected, which means below the laboratory limit rather than an absence of lead.

No community here has PFAS above the federal limit on record. State inspectors recorded significant deficiencies at 38 of them.

Frequently Asked Questions

Is Lake County tap water safe to drink?▼
96% of communities have no open violation. No community has PFAS above the federal limit on record.
What is the lead level in Lake County?▼
Among communities with a detection the median is 6.29 ppb, 42% of the 15 ppb action level. 28 reported none detected and 0 reported no result.
How many water systems serve Lake County?▼
40 community water systems serve 56 communities here.
← Back to Illinois water quality overview