Jefferson County, KY
drinking water quality
793,881 residents · 1 public water system · 38 ZIP codes
EPA sampled 1 of 1 public water system here, together serving about 806,997 people. The highest reading was PFOA at 7.5 ng/L at Louisville Water Company. 1 of the sampled system was above a federal limit. Last sampled 9/27/2023.
What was found
| Compound | Highest result | Federal limit | Ratio |
|---|---|---|---|
| PFOA | 7.5 ng/L | 4 ng/L | 1.9× |
Also detected, with no federal limit set: PFPeA (4.1 ng/L), PFHxA (3.6 ng/L), PFBS (3 ng/L).
What this means
PFAS are industrial chemicals that EPA describes as breaking down only very slowly in the environment. In April 2024 EPA set the first enforceable national limits: 4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS, PFNA and GenX.
These figures are county-level and come from EPA’s sampling of public water systems. They describe the worst result found in the county, not what comes out of any particular tap — that depends on which system serves the address, and on the plumbing in the building. A private well is not covered by this programme at all.
ZIP codes in Jefferson County
40023 · 40025 · 40041 · 40118 · 40202 · 40203 · 40204 · 40205 · 40206 · 40207 · 40208 · 40209 · 40210 · 40211 · 40212 · 40213 · 40214 · 40215 · 40216 · 40217 · 40218 · 40219 · 40220 · 40221 · 40222 · 40223 · 40228 · 40229 · 40231 · 40241 · 40242 · 40243 · 40245 · 40258 · 40272 · 40280 · 40291 · 40299
Readings are county-level, so every ZIP here shares the figure above. Search your ZIP on the map to see it in context.