States › Illinois › Knox County

Knox County, IL Water Quality

Water quality data for 14 public water systems serving Knox County, Illinois — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 14 water systems · 15 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

Knox County Earns a B

Knox County: 15 communities across 14 water systems. 93.3% have no open violations.

  • Median lead where detected: 3.51 ppb
  • 8 communities with a lead detection, 7 reporting none detected
  • 2 communities with PFAS above the federal limit
  • 7 with significant inspection deficiencies
  • 93.3% of communities have no open violations
3.51 ppb
Median Lead Level
County-wide, 90th percentile
14
Water Systems
Active CWS & NTNCWS
93%
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
  • Oak Run
    4.00 ppb
    No federal limits exceeded on record
    B
  • Maquon
    Not detected
    No federal limits exceeded on record
    B
  • Rio
    1.60 ppb
    No federal limits exceeded on record
    B
  • Williamsfield
    3.01 ppb
    1 health-based violation since 2015
    B
  • Yates City
    5.37 ppb
    Lead at 5.37 ppb, above a third of the action level
    B
⚠ Needs Attention
  • Wataga
    1.30 ppb
    1 violation currently open
    D
  • Galesburg
    Not detected
    PFAS above the limit at 1 of 1 sampling points
    D
  • Abingdon
    Not detected
    PFAS above the limit at 1 of 1 sampling points
    C
  • Henderson
    0.60 ppb
    4 significant inspection deficiencies
    C
  • Altona
    4.10 ppb
    3 significant inspection deficiencies
    B
County Lead Level — Median 3.51 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 3.51 ppb — 23.4% of the federal action level
Systems by Lead Level
Under 5 ppb
6
5 – 10 ppb
1
10 – 15 ppb
1
No Data
7

All Cities in Knox County

Galesburg Not detected D
Abingdon Not detected C
Knoxville Not detected B
Wataga 1.30 ppb D
Oak Run 4.00 ppb B
Oneida Not detected B
Williamsfield 3.01 ppb B
Yates City 5.37 ppb B
Altona 4.10 ppb B
East Galesburg Not detected B
Victoria Not detected B
Henderson 0.60 ppb C
Maquon Not detected B
Rio 1.60 ppb B
St. Augustine 10.00 ppb B
Showing 15 cities
No active violations Active violations

About Knox County Drinking Water

Knox County is served by 14 water systems covering 15 communities. 93% have no open violations.

Of the communities reporting lead results, 8 recorded a detection, with a median of 3.51 ppb — 23% of the federal action level. 7 reported none detected, which means below the laboratory limit rather than an absence of lead.

2 of 15 communities have PFAS above the limits EPA set in 2024, measured as a running annual average at each sampling point. State inspectors recorded significant deficiencies at 7 of them.

Frequently Asked Questions

Is Knox County tap water safe to drink?▼
93% of communities have no open violation. 2 of 15 have PFAS above the federal limit, which is the main open concern.
What is the lead level in Knox County?▼
Among communities with a detection the median is 3.51 ppb, 23% of the 15 ppb action level. 7 reported none detected and 0 reported no result.
How many water systems serve Knox County?▼
14 community water systems serve 15 communities here.
← Back to Illinois water quality overview