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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 1 cities serving 806,997 residents
Jefferson County in Kentucky has an average water quality score of 84/100 (Grade B) based on analysis of 1 municipal water systems. The county's water systems serve approximately 806,997 residents.
Overall, Jefferson County demonstrates good water quality standards. 1 of 1 cities exceed the county average, with Louisville leading with a score of 84/100.
1 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | Louisville Biggest deduction: PFOA detected at up to 7.5 ppt in UCMR5 sampling (2023-11-15), at or above EPA's 4 ppt MCL (−10 pts) | 84 | B | 806,997 |
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 |
|---|---|---|---|---|---|
| PFAS (PFOA/PFOS max, UCMR5) | 7.5 ppt | 7.5 ppt | 4 ppt | 187.5% | 1 |
| TTHM (2012–2019 avg) | 21.897 ug/L | 21.897 ug/L | 80 ug/L | 27.4% | 1 |
| HAA5 (2012–2019 avg) | 14.319 ug/L | 14.319 ug/L | 60 ug/L | 23.9% | 1 |
| Fluoride (2012–2019 avg) | 0.814 mg/L | 0.814 mg/L | 4 mg/L | 20.3% | 1 |
| Radium (2012–2019 avg) | 0.406 pCi/L | 0.406 pCi/L | 5 pCi/L | 8.1% | 1 |
| Lead (90th percentile) | 1.1 ppb | 1.1 ppb | 15 ppb | 7.3% | 1 |
| Nitrate (2012–2019 avg) | 0.662 mg/L | 0.662 mg/L | 10 mg/L | 6.6% | 1 |
| Arsenic (2012–2019 avg) | 0 ug/L | 0 ug/L | 10 ug/L | 0% | 1 |
Water quality in Jefferson County, Kentucky reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 1 municipal water systems serving a combined population of over 806,997 residents.
The county shows strong water quality performance, with scores ranging from 84/100 in Louisville to 84/100 in Louisville. This 0-point spread indicates relatively consistent water quality standards across municipal systems.
The most prevalent contaminants detected across Jefferson County water systems include PFAS (PFOA/PFOS max, UCMR5), TTHM (2012–2019 avg), 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.
Jefferson 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.
Jefferson County has an average water quality score of 84/100 (Grade B) based on analysis of 1 municipal water systems serving 806,997 residents.
Louisville has the highest water quality score in Jefferson County at 84/100. View the detailed report for Louisville.
Most cities in Jefferson 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.