States › Illinois › Monroe County

Monroe County, IL Water Quality

Water quality data for 5 public water systems serving Monroe County, Illinois — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 5 water systems · 5 cities
⚠️
Caution Advised — Some Systems Need Attention

Some systems have elevated lead levels or active violations. Check your specific city below.

C

Monroe County Earns a C

Monroe County: 5 communities across 5 water systems. 80.0% have no open violations.

  • Median lead where detected: 1.75 ppb
  • 2 communities with a lead detection, 3 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 5 with significant inspection deficiencies
  • 80.0% of communities have no open violations
1.75 ppb
Median Lead Level
County-wide, 90th percentile
5
Water Systems
Active CWS & NTNCWS
80%
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
  • Columbia
    Not detected
    2 significant inspection deficiencies
    A
  • Valmeyer
    Not detected
    2 significant inspection deficiencies
    A
  • Waterloo
    1.40 ppb
    3 significant inspection deficiencies
    B
  • Maeystown
    Not detected
    Copper above the 1,300 ppb action level
    D
  • Hecker
    2.10 ppb
    Copper above the 1,300 ppb action level
    D
⚠ Needs Attention
  • Hecker
    2.10 ppb
    Copper above the 1,300 ppb action level
    D
  • Maeystown
    Not detected
    Copper above the 1,300 ppb action level
    D
  • Waterloo
    1.40 ppb
    3 significant inspection deficiencies
    B
  • Columbia
    Not detected
    2 significant inspection deficiencies
    A
  • Valmeyer
    Not detected
    2 significant inspection deficiencies
    A
County Lead Level — Median 1.75 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 1.75 ppb — 11.7% of the federal action level
Systems by Lead Level
Under 5 ppb
2
No Data
3

All Cities in Monroe County

Columbia Not detected A
Waterloo 1.40 ppb B
Valmeyer Not detected A
Hecker 2.10 ppb D
Maeystown Not detected D
Showing 5 cities
No active violations Active violations

About Monroe County Drinking Water

Monroe County is served by 5 water systems covering 5 communities. 80% have no open violations.

Of the communities reporting lead results, 2 recorded a detection, with a median of 1.75 ppb — 12% of the federal action level. 3 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 5 of them.

Frequently Asked Questions

Is Monroe County tap water safe to drink?▼
80% of communities have no open violation. No community has PFAS above the federal limit on record.
What is the lead level in Monroe County?▼
Among communities with a detection the median is 1.75 ppb, 12% of the 15 ppb action level. 3 reported none detected and 0 reported no result.
How many water systems serve Monroe County?▼
5 community water systems serve 5 communities here.
← Back to Illinois water quality overview