Tap water report · updated November 2026
Louisville tap water: hard water, PFOA samples up to 7.5 ppt (EPA limit 4)
What’s in the water Louisville Water delivers to 806,997 people, from national testing by the U.S. Environmental Protection Agency (EPA) and the utility’s own report.
Short answer
Louisville tap water is hard: about 7.5 grains per gallon (128 milligrams per liter (mg/L)), according to published water quality data from Louisville Water (2025). The U.S. Environmental Protection Agency’s (EPA’s) 2023 testing found PFOA (a PFAS “forever chemical”) at 7.5 parts per trillion (ppt) in its highest samples, above the 4 ppt limit utilities must meet by 2029. The system had no health-based violations in the five years through September 2026.
Sources: Louisville Water 2025 data, EPA UCMR 5, EPA SDWIS 2026Q3 · Sources and method
How Louisville compares with the 40 systems we track
Hardness
17th hardest
of 34 systems
PFOA / PFOS
5th highest
of 11 that detected any
Size
25th largest
of 40 by people served
01 · What it means
What these readings mean for your home
Each reading in plain English: what it is, how Louisville compares with the other systems we track, and whether there’s anything to do. The tags follow EPA’s limits and reference levels where EPA has one; for hardness, which has no EPA limit, they follow the U.S. Geological Survey (USGS) scale and Minnesota’s health department. New to the acronyms? Every term, in plain English.
Hardness
Worth acting onHardness is dissolved calcium and magnesium, picked up as water runs through rock. It isn’t a health issue (EPA has no limit for it). It’s what leaves white crust on faucets, spots on glasses and scale inside your water heater. It’s measured in grains per gallon (gpg); 1 gpg is about 17 mg of minerals in a liter.
Here: At 7.5 gpg, Louisville water is hard, the 17th-hardest of the 34 systems we track. Most homes here notice scale and spotting.
What to do: A water softener is the only whole-house system that removes hardness. Size it to your household so it doesn’t waste salt.
What the research says: Studies tie hard water to more soap use and scale. Observational studies link it with somewhat more eczema in babies, but in the largest trial a softener didn’t improve existing eczema. The studies →
Learn more →PFAS (PFOA and PFOS)
Worth acting onPFAS are a family of thousands of manufactured chemicals used in many consumer and industrial products. They break down very slowly, which is why people call them "forever chemicals." PFOA and PFOS are the two EPA regulates most tightly. They’re measured in parts per trillion (ppt): 1 ppt is about one drop in 20 Olympic swimming pools.
Here: Louisville’s highest PFOA sample was 7.5 ppt, about 1.9 times EPA’s 4 ppt limit, the 5th-highest of the 40 we track. 11 of the 40 had a sample over the limit; 29 had none detected at all. These are samples from EPA’s 2023 testing, not a violation: utilities have until 2029 to get under the limit on a yearly average.
What to do: A filter on the tap you drink and cook from handles it. Look for reverse osmosis certified to NSF/ANSI 58, or carbon certified to NSF/ANSI 53, for PFOA and PFOS by name.
What the research says: EPA and the National Academies link PFOA and PFOS exposure to higher cholesterol, lower vaccine response, lower birth weight and some cancers, mostly over years of drinking the water. The studies →
Learn more →Disinfectant
Nothing to doUtilities add a small amount of chlorine, or chloramine (chlorine combined with a little ammonia), so germs can’t grow in the pipes on the way to your tap. EPA allows up to 4 milligrams per liter (mg/L) of either and says water within its standards can be used for drinking, cooking and bathing.
Here: Louisville uses chloramine, like 20 other systems we track. It lasts longer in pipes than chlorine and is harder to filter.
What to do: For taste, use catalytic carbon or a filter certified to NSF/ANSI 42 for chloramine. Fish tanks and home dialysis need it removed completely.
What the research says: Health agencies call these levels acceptable for drinking and bathing; dialysis and fish tanks are the exceptions. Studies haven’t shown shower chlorine harms skin or hair. The studies →
Learn more →Health-based violations
Nothing to doA health-based violation means the utility broke a federal drinking water rule tied to health: it went over a limit, or skipped a required treatment step. Missing a paperwork deadline doesn’t count.
Here: Louisville’s system had none in the five years through September 2026. That’s normal for a large system: 36 of the 40 we track had none.
What to do: Nothing to do.
Learn more →How Louisville compares: highest PFOA or PFOS sample
Parts per trillion (ppt), from EPA’s 2023–25 testing. The dashed line is EPA’s limit of 4.
- Miami33.0 PFOS
- El Paso8.5 PFOS
- Fort Worth8.3 PFOA
- Philadelphia8.1 PFOA
- Louisville7.5 PFOA
- Tampa6.9 PFOS
- Dallas6.3 PFOA
- San Jose6.2 PFOS
- Cincinnati6.1 PFOS
- Columbus5.3 PFOA
- Austin4.8 PFOS
If you live in Louisville
- Size a softener for Louisville water At 7.5 grains per gallon, the calculator works out the capacity for your household.
- What softeners cost Store and dealer prices, with what each includes.
- Drinking water filters listed for PFOA and PFOS Under-sink systems with a public NSF, WQA or IAPMO listing, and what they cost.
- Whole-house filters for chloramine Louisville uses chloramine, which ordinary carbon removes slowly. What to look for and what it costs.
Louisville’s water is hard. Softeners from brands that sell online, at their own store prices:
We may earn a commission from these links.
02 · The full results
Every PFAS result EPA recorded
In EPA’s national testing (sampled 2023), Louisville’s highest samples reached PFOA at 7.5 ppt, above EPA’s 4 ppt limit. These are individual samples, not a compliance finding: water systems have until 2029 to meet the limit, judged on a yearly average.
Results from EPA’s national testing program (UCMR 5) for Louisville Water, 2 sampling points, February 2023 to November 2023. Concentrations in parts per trillion (ppt).
| Chemical | Samples | Detected | Highest | EPA limit |
|---|---|---|---|---|
| PFOA (perfluorooctanoic acid) | 6 | 1 | 7.5 | 4 |
| PFOS (perfluorooctane sulfonic acid) | 6 | 0 | none | 4 |
| PFHxS | 6 | 0 | none | 10 |
| PFNA | 6 | 0 | none | 10 |
| HFPO-DA (GenX) | 6 | 0 | none | 10 |
"None" means every sample was under EPA’s reporting level (4 ppt for PFOA). PFHxS, PFNA and HFPO-DA (GenX) are three other PFAS chemicals; EPA proposed removing their limits in May 2026, and that isn’t final.
03 · Where it comes from
The source, and who else drinks it
Louisville Water draws from the Ohio River: the Crescent Hill plant treats water pumped directly from the river, and the B.E. Payne plant treats groundwater collected from the aquifer by riverbank filtration.
Louisville Water serves about 806,997 people directly, and 9 other water systems buy water from it, serving about 214,247 more. If you live in one of them, most of what’s on this page describes your water too, though hardness and disinfectant can change if your system blends in its own wells.
The B.E. Payne plant pulls its water through the riverbank aquifer beside the Ohio River instead of from an open intake.
Louisville’s water system had no health-based violations in the five years through September 2026, according to EPA’s federal database.
Largest systems that buy from Louisville Water
- Hardin County Water District #276,326
- Hardin County Water District #130,230
- Mt Washington Water Company23,760
- Shelbyville Water & Sewer Commission23,760
- Taylorsville Water Works22,286
- North Shelby Water District14,660
- North Nelson Water District13,365
- West Shelby Water District6,994
- Lebanon Junction Water Works2,866
From EPA’s federal drinking water database (SDWIS), 2026Q3: community systems with an active connection buying from KY0560258. Population served.
ZIP codes Louisville Water reports serving (48)
40010 · 40014 · 40023 · 40025 · 40026 · 40031 · 40041 · 40047 · 40056 · 40059 · 40109 · 40110 · 40118 · 40150 · 40165 · 40202 · 40203 · 40204 · 40205 · 40206 · 40207 · 40208 · 40209 · 40210 · 40211 · 40212 · 40213 · 40214 · 40215 · 40216 · 40217 · 40218 · 40219 · 40220 · 40222 · 40223 · 40228 · 40229 · 40241 · 40242 · 40243 · 40245 · 40258 · 40272 · 40280 · 40291 · 40292 · 40299
From EPA’s UCMR 5 ZIP file. A ZIP can be served by more than one system; your water bill names yours. Look up any ZIP.
04 · Questions
Louisville water questions
Is Louisville tap water safe to drink?
The U.S. Environmental Protection Agency (EPA) doesn’t grade a city’s tap water as safe or unsafe; it sets limits and records violations. By that record, Louisville’s water system had no health-based violations of federal drinking water rules in the five years through September 2026. Separately, EPA’s 2023 testing found PFOA or PFOS (two PFAS “forever chemicals”) samples above the 4 parts per trillion (ppt) limit that utilities must meet, on a yearly average, by 2029. A filter certified to NSF/ANSI 53 or 58 for PFOA and PFOS addresses it at the tap.
Is Louisville tap water hard?
Louisville tap water is hard: about 7.5 grains per gallon (128 milligrams per liter (mg/L)), according to published water quality data from Louisville Water (2025).
Does Louisville tap water have PFAS?
In the U.S. Environmental Protection Agency’s (EPA’s) national testing (sampled 2023), Louisville’s highest samples reached PFOA (a PFAS “forever chemical”) at 7.5 parts per trillion (ppt), above EPA’s 4 ppt limit. These are individual samples, not a compliance finding: water systems have until 2029 to meet the limit, judged on a yearly average.
Does Louisville use chlorine or chloramine?
Chloramine. Louisville Water adds chlorine and then ammonia to stabilize the disinfectant, and its report lists the residual as Chlorine Residual (Chloramines).
Has Louisville’s water system had violations?
Louisville’s water system had no health-based violations in the five years through September 2026, according to the U.S. Environmental Protection Agency’s (EPA’s) federal database.
Nearest cities we cover
Sources
- 01Louisville Water, 2025 water quality data (hardness), read 2026-11-04
- 02Louisville Water (source water)
- 03EPA, Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) occurrence data, file posted 2026-10-15
- 04EPA, Safe Drinking Water Information System via ECHO, 2026Q3 file
- 05EPA, PFAS National Primary Drinking Water Regulation, 89 FR 32532
- 06USGS Water Science School, "Hardness of Water"
EPA system ID KY0560258 · Louisville Water