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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Water quality data for 2 cities serving 166,956 residents
Johnson County in Kansas has an average water quality score of 94/100 (Grade A) based on analysis of 2 municipal water systems. The county's water systems serve approximately 166,956 residents.
Overall, Johnson County demonstrates good water quality standards. 1 of 2 cities exceed the county average, with Gardner leading with a score of 98/100.
2 cities ranked by water quality score
Real EPA readings across county water systems (lead: latest 90th percentile; PFAS: UCMR5 2023–2026; others: 2012–2019 averages)
| Contaminant | Avg Level | Max Level | EPA Limit | % of Limit | Cities |
|---|---|---|---|---|---|
| TTHM (2012–2019 avg) | 40.29 ug/L | 45.789 ug/L | 80 ug/L | 50.4% | 2 |
| Lead (90th percentile) | 7.05 ppb | 11 ppb | 15 ppb | 47% | 2 |
| HAA5 (2012–2019 avg) | 16.695 ug/L | 17.721 ug/L | 60 ug/L | 27.8% | 2 |
| Fluoride (2012–2019 avg) | 0.792 mg/L | 0.94 mg/L | 4 mg/L | 19.8% | 2 |
| Arsenic (2012–2019 avg) | 0.906 ug/L | 1.688 ug/L | 10 ug/L | 9.1% | 2 |
| Nitrate (2012–2019 avg) | 0.436 mg/L | 0.451 mg/L | 10 mg/L | 4.4% | 2 |
| PFAS (PFOA/PFOS max, UCMR5) | 0 ppt | 0 ppt | 4 ppt | 0% | 2 |
| Radium (2012–2019 avg) | 0 pCi/L | 0 pCi/L | 5 pCi/L | 0% | 2 |
Recent violations across county water systems
Monitoring & reporting — Monitoring and Reporting (DBP) - Total Haloacetic Acids (HAA5)
11/30/2020
Water quality in Johnson County, Kansas reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 2 municipal water systems serving a combined population of over 166,956 residents.
The county shows strong water quality performance, with scores ranging from 89/100 in Olathe to 98/100 in Gardner. This 9-point spread indicates relatively consistent water quality standards across municipal systems.
The most prevalent contaminants detected across Johnson County water systems include TTHM (2012–2019 avg), Lead (90th percentile), HAA5 (2012–2019 avg). At least one reading averages above 50% of its EPA limit across the county's systems, worth attention from residents and utilities.
Johnson County's water quality is generally good. Residents can feel confident in their tap water quality, though those with specific health concerns or sensitivity to certain contaminants may still benefit from filtration. Regular review of your city's annual Consumer Confidence Report is recommended.
Johnson County has an average water quality score of 94/100 (Grade A) based on analysis of 2 municipal water systems serving 166,956 residents.
Gardner has the highest water quality score in Johnson County at 98/100. View the detailed report for Gardner.
Most cities in Johnson County have water that meets EPA standards. However, a water filter can provide additional protection and improve taste. The need depends on your specific city and any personal health considerations.
Click on any city in the rankings table above to view its detailed water quality report, including contaminant levels, EPA compliance history, and filter recommendations.