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Grundy County, IL Water Quality

Water quality data for 9 public water systems serving Grundy County, Illinois — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 9 water systems · 10 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

Grundy County Earns a B

Grundy County: 10 communities across 9 water systems. 100.0% have no open violations.

  • Median lead where detected: 1.80 ppb
  • 3 communities with a lead detection, 7 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 6 with significant inspection deficiencies
  • 100.0% of communities have no open violations
1.8 ppb
Median Lead Level
County-wide, 90th percentile
9
Water Systems
Active CWS & NTNCWS
100%
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
  • Diamond
    Not detected
    No federal limits exceeded on record
    B
  • Minooka
    1.07 ppb
    1 health-based violation since 2015
    A
  • Morris
    Not detected
    1 significant inspection deficiency
    A
  • Kinsman
    1.80 ppb
    2 significant inspection deficiencies
    B
  • Coal City
    Not detected
    7 health-based violations since 2015
    B
⚠ Needs Attention
  • Braceville
    4.96 ppb
    Copper above the 1,300 ppb action level
    C
  • Gardner
    Not detected
    Copper above the 1,300 ppb action level
    C
  • Mazon
    Not detected
    Copper above the 1,300 ppb action level
    B
  • South Wilmington
    Not detected
    3 significant inspection deficiencies
    B
  • Coal City
    Not detected
    7 health-based violations since 2015
    B
County Lead Level — Median 1.8 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 1.8 ppb — 12% of the federal action level
Systems by Lead Level
Under 5 ppb
3
No Data
7

All Cities in Grundy County

Morris Not detected A
Minooka 1.07 ppb A
Coal City Not detected B
Diamond Not detected B
Gardner Not detected C
Mazon Not detected B
South Wilmington Not detected B
Braceville 4.96 ppb C
Carbon Hill Not detected B
Kinsman 1.80 ppb B
Showing 10 cities
No active violations Active violations

About Grundy County Drinking Water

Grundy County is served by 9 water systems covering 10 communities. No community here has an open violation on record.

Of the communities reporting lead results, 3 recorded a detection, with a median of 1.80 ppb — 12% of the federal action level. 7 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 6 of them.

Frequently Asked Questions

Is Grundy County tap water safe to drink?▼
No community in Grundy County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Grundy County?▼
Among communities with a detection the median is 1.80 ppb, 12% of the 15 ppb action level. 7 reported none detected and 0 reported no result.
How many water systems serve Grundy County?▼
9 community water systems serve 10 communities here.
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