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Johnson County, KS Water Quality

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

📅 2026 Report 🔄 Data updated 2026 Q2 📍 5 water systems · 19 cities
✅
Excellent — All Systems Performing Well

Water quality across the county is outstanding with minimal violations and very low lead levels.

A

Johnson County Earns a A

Johnson County: 19 communities across 5 water systems. 94.7% have no open violations.

  • Median lead where detected: 6.48 ppb
  • 18 communities with a lead detection, 1 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 1 with significant inspection deficiencies
  • 94.7% of communities have no open violations
6.48 ppb
Median Lead Level
County-wide, 90th percentile
5
Water Systems
Active CWS & NTNCWS
94%
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
  • Overland Park
    6.48 ppb
    Lead at 6.48 ppb, above a third of the action level
    A
  • Olathe
    11.00 ppb
    Lead at 11.00 ppb, above a third of the action level
    A
  • Shawnee
    6.48 ppb
    Lead at 6.48 ppb, above a third of the action level
    A
  • Lenexa
    6.48 ppb
    Lead at 6.48 ppb, above a third of the action level
    A
  • Leawood
    6.48 ppb
    Lead at 6.48 ppb, above a third of the action level
    A
⚠ Needs Attention
  • De Soto
    Not detected
    3 violations currently open
    D
  • Gardner
    3.10 ppb
    1 significant inspection deficiency
    A
  • Overland Park
    6.48 ppb
    Lead at 6.48 ppb, above a third of the action level
    A
  • Olathe
    11.00 ppb
    Lead at 11.00 ppb, above a third of the action level
    A
  • Shawnee
    6.48 ppb
    Lead at 6.48 ppb, above a third of the action level
    A
County Lead Level — Median 6.48 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 6.48 ppb — 43.2% of the federal action level
Systems by Lead Level
Under 5 ppb
1
5 – 10 ppb
16
10 – 15 ppb
1
No Data
1

All Cities in Johnson County

Overland Park 6.48 ppb A
Olathe 11.00 ppb A
Shawnee 6.48 ppb A
Lenexa 6.48 ppb A
Leawood 6.48 ppb A
Prairie Village 6.48 ppb A
Gardner 3.10 ppb A
Merriam 6.48 ppb A
Mission 6.48 ppb A
Roeland Park 6.48 ppb A
De Soto Not detected D
Fairway 6.48 ppb A
Mission Hills 6.48 ppb A
Spring Hill 6.48 ppb A
Westwood 6.48 ppb A
Edgerton 5.20 ppb B
Lake Quivira 6.48 ppb A
Westwood Hills 6.48 ppb A
Mission Woods 6.48 ppb A
Showing 19 cities
No active violations Active violations

About Johnson County Drinking Water

Johnson County is served by 5 water systems covering 19 communities. 95% have no open violations.

Of the communities reporting lead results, 18 recorded a detection, with a median of 6.48 ppb — 43% of the federal action level. 1 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 1 of them.

Frequently Asked Questions

Is Johnson County tap water safe to drink?▼
95% of communities have no open violation. No community has PFAS above the federal limit on record.
What is the lead level in Johnson County?▼
Among communities with a detection the median is 6.48 ppb, 43% of the 15 ppb action level. 1 reported none detected and 0 reported no result.
How many water systems serve Johnson County?▼
5 community water systems serve 19 communities here.
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