Jefferson County, Kentucky: drinking water report. Jefferson County – Louisville – serves about 780,000 residents.
Jefferson County – Louisville – serves about 780,000 residents. Louisville Water Company draws from the Ohio River, operating a treatment system that has earned national recognition for water quality. The utility was the first in the US to receive the Partnership for Safe Water's excellence award for 20 consecutive years – a track record that few utilities can match.
The Ohio River at Louisville carries the accumulated discharges of communities and industries upstream, but Louisville Water Company's advanced treatment – including riverbank filtration, ozone, and biologically active carbon – produces a finished product that consistently wins taste tests against other Ohio River communities.
UCMR5 data shows low-level PFAS detections in the Louisville system. Kentucky does not have state-specific PFAS MCLs. According to the Kentucky Division of Water's 2024 compliance data, Louisville Water Company met all federal standards with significant margin. The utility's proactive treatment approach means it handles emerging contaminants that many other Ohio River utilities do not yet address.
Louisville Water Company's treatment is among the best on the Ohio River. The main household variable is your building's internal plumbing.
Check your water for data in your area. For most Louisville residents, the supply is clean. A basic carbon filter improves chlorine taste. Our water filter guide covers options. Pull your detailed report, and visit our Kentucky page for statewide data.
Drinking water is one exposure route. These federal datasets also cover Jefferson County, KY.
The EPA places Jefferson County, KY in Zone 1 - the EPA's highest-risk category, where the predicted average indoor radon level is above 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
64% of homes in Jefferson County, KY were built before 1980, and 21% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Jefferson County, KY averages 9 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide
4 public water systems serving Jefferson County, KY have EPA lead testing on record. The reported lead sample skews toward systems that already flagged a problem, so its exceedance rate is not directly comparable with other areas. 1 water systems serving Jefferson County, KY carry a health-based EPA Safe Drinking Water Act violation.
| Most-cited violation type | Systems affected |
|---|---|
| Haloacetic Acids (HAA5) | 1 |
Source: EPA Lead and Copper Rule 90th-percentile tap sampling and EPA SDWIS Safe Drinking Water Act enforcement records, aggregated from the public water systems serving this county. Figures are counts of water systems, not a test of any individual home or tap.