Private wells
Kentucky well water: who's on a well and what to test for
People on private wells
297,100
Homes on wells
7.1%
Est. above arsenic limit
6,700
Every Kentucky county
Sorted by people on private wells. Arsenic and nitrate are modeled for typical wells in the county, not measured at yours; depth is the median of domestic well records.
| Pike County | 25,700 | 45% | 2.5% | 0.0 | 83 ft |
| Letcher County | 14,100 | 66% | 2.2% | 0.0 | 112 ft |
| Graves County | 14,100 | 39% | 2.4% | 0.1 | 165 ft |
| Floyd County | 13,200 | 38% | 2.1% | 0.0 | 92 ft |
| Calloway County | 10,900 | 32% | 2.1% | 0.3 | 104 ft |
| Meade County | 10,600 | 36% | 1.5% | 1.6 | 210 ft |
| Whitley County | 10,400 | 29% | 1.7% | 0.1 | 135 ft |
| Perry County | 10,300 | 37% | 2.0% | 0.0 | 120 ft |
| Knott County | 10,200 | 74% | 2.0% | 0.0 | 102 ft |
| Harlan County | 9,100 | 34% | 1.2% | 0.0 | 145 ft |
| Marshall County | 7,400 | 22% | 2.4% | 0.6 | 70 ft |
| Breathitt County | 6,800 | 50% | 2.1% | 0.0 | 82 ft |
| Hardin County | 6,800 | 6% | 1.4% | 1.1 | 150 ft |
| Johnson County | 6,700 | 30% | 2.3% | 0.0 | 100 ft |
| Lawrence County | 6,300 | 40% | 2.4% | 0.0 | 100 ft |
| McCracken County | 6,000 | 9% | 3.3% | 0.2 | 115 ft |
| Greenup County | 5,900 | 17% | 3.1% | 0.1 | 75 ft |
| Leslie County | 5,500 | 54% | 1.6% | 0.0 | 105 ft |
| Clay County | 5,300 | 29% | 1.8% | 0.0 | 75 ft |
| Morgan County | 4,900 | 42% | 2.6% | 0.0 | 185 ft |
| Bell County | 4,900 | 20% | 1.4% | 0.0 | 111 ft |
| Breckinridge County | 4,400 | 23% | 1.6% | 0.5 | 220 ft |
| Pulaski County | 4,400 | 7% | 1.6% | 0.8 | 100 ft |
| Ballard County | 4,000 | 50% | 3.6% | 0.2 | 136 ft |
| Martin County | 3,900 | 39% | 2.5% | 0.0 | 80 ft |
| Knox County | 3,400 | 12% | 2.1% | 0.1 | 100 ft |
| Casey County | 3,300 | 21% | 1.8% | 0.4 | 95 ft |
| Wayne County | 3,300 | 17% | 1.7% | 0.8 | 100 ft |
| Christian County | 3,200 | 4% | 1.3% | 2.0 | 114 ft |
| Grayson County | 3,200 | 14% | 1.5% | 0.3 | 200 ft |
| Bullitt County | 3,200 | 4% | 16.8% | 0.3 | 120 ft |
| Laurel County | 3,100 | 5% | 2.1% | 0.3 | 120 ft |
| Wolfe County | 3,100 | 48% | 2.5% | 0.0 | 185 ft |
| Magoffin County | 2,900 | 25% | 2.1% | 0.0 | 80 ft |
| Carter County | 2,800 | 11% | 2.5% | 0.1 | 80 ft |
| Carlisle County | 2,700 | 57% | 3.4% | 0.1 | 180 ft |
| Hickman County | 2,500 | 58% | 4.0% | 0.1 | 150 ft |
| Jackson County | 2,500 | 21% | 2.1% | 0.1 | 82 ft |
| Jefferson County | 2,300 | 0% | 11.3% | 0.6 | 84 ft |
| Logan County | 2,300 | 8% | 2.0% | 3.5 | 90 ft |
| Russell County | 2,300 | 13% | 1.5% | 1.1 | 75 ft |
| Todd County | 2,200 | 16% | 1.5% | 2.0 | 100 ft |
| McCreary County | 2,000 | 13% | 1.4% | 0.1 | 108 ft |
| Elliott County | 1,800 | 29% | 2.2% | 0.0 | 186 ft |
| Lincoln County | 1,600 | 7% | 2.8% | 0.8 | 65 ft |
| Livingston County | 1,600 | 18% | 1.9% | 0.1 | 160 ft |
| Adair County | 1,400 | 8% | 1.6% | 1.1 | 80 ft |
| Hart County | 1,400 | 7% | 1.3% | 0.8 | 200 ft |
| Henderson County | 1,400 | 3% | 10.2% | 0.5 | 90 ft |
| Owsley County | 1,300 | 35% | 1.9% | 0.0 | 65 ft |
| Daviess County | 1,300 | 1% | 6.5% | 0.5 | 100 ft |
| Boyd County | 1,300 | 3% | 2.2% | 0.1 | 140 ft |
| Lewis County | 1,200 | 9% | 4.5% | 0.1 | 60 ft |
| Ohio County | 1,100 | 4% | 3.6% | 0.3 | 100 ft |
| Crittenden County | 1,100 | 12% | 2.9% | 0.1 | 161 ft |
| Larue County | 1,000 | 7% | 1.7% | 1.9 | 110 ft |
| Taylor County | 900 | 4% | 1.5% | 2.0 | 75 ft |
| Trigg County | 890 | 6% | 1.3% | 0.7 | 145 ft |
| Lee County | 850 | 15% | 2.8% | 0.0 | 80 ft |
| Fulton County | 850 | 14% | 4.6% | 0.1 | 120 ft |
| Hopkins County | 790 | 2% | 4.6% | 0.3 | 100 ft |
| Rockcastle County | 730 | 5% | 3.6% | 0.2 | 90 ft |
| Rowan County | 730 | 3% | 3.4% | 0.1 | 47 ft |
| Boone County | 690 | 1% | 5.2% | 0.5 | 83 ft |
| Allen County | 690 | 4% | 1.8% | 1.2 | 80 ft |
| Caldwell County | 690 | 6% | 2.0% | 0.4 | 120 ft |
| Nelson County | 680 | 2% | 10.9% | 1.4 | 76 ft |
| Lyon County | 660 | 13% | 1.8% | 0.3 | 160 ft |
| Webster County | 500 | 4% | 5.1% | 0.3 | 116 ft |
| Oldham County | 490 | 1% | 10.1% | 1.2 | 70 ft |
| Barren County | 440 | 1% | 1.4% | 2.5 | 90 ft |
| Boyle County | 440 | 2% | 1.4% | 2.1 | n/a |
| Clinton County | 390 | 5% | 1.8% | 1.5 | 93 ft |
| Woodford County | 380 | 2% | 2.7% | 2.4 | 90 ft |
| Madison County | 350 | 0% | 2.1% | 0.9 | 50 ft |
| Campbell County | 350 | 0% | 4.8% | 0.6 | 84 ft |
| Union County | 350 | 3% | 18.7% | 0.4 | 155 ft |
| Muhlenberg County | 320 | 1% | 4.4% | 0.7 | 80 ft |
| Jessamine County | 310 | 1% | 2.9% | 1.8 | 79 ft |
| Trimble County | 270 | 3% | 3.3% | 0.8 | n/a |
| Menifee County | 260 | 5% | 3.2% | 0.1 | 50 ft |
| Simpson County | 240 | 1% | 2.0% | 5.2 | 65 ft |
| Powell County | 210 | 2% | 2.8% | 0.1 | 60 ft |
| Metcalfe County | 190 | 2% | 1.3% | 1.1 | 80 ft |
| Fayette County | 180 | 0% | 1.8% | 2.1 | 92 ft |
| Montgomery County | 170 | 1% | 4.3% | 0.9 | 30 ft |
| Garrard County | 160 | 1% | 2.7% | 1.1 | 50 ft |
| Monroe County | 150 | 1% | 1.1% | 1.3 | 85 ft |
| Franklin County | 140 | 0% | 4.7% | 0.9 | 66 ft |
| Scott County | 140 | 0% | 1.6% | 1.0 | 85 ft |
| Mercer County | 130 | 1% | 1.8% | 2.4 | n/a |
| Green County | 130 | 1% | 1.4% | 1.6 | 66 ft |
| Warren County | 130 | 0% | 2.3% | 3.2 | 94 ft |
| Butler County | 130 | 1% | 4.6% | 0.5 | 76 ft |
| Clark County | 110 | 0% | 1.9% | 1.2 | 95 ft |
| McLean County | 100 | 1% | 7.6% | 0.6 | 50 ft |
| Bath County | 100 | 1% | 8.3% | 0.9 | n/a |
| Cumberland County | 90 | 2% | 1.8% | 0.3 | 59 ft |
| Spencer County | 80 | 0% | 4.0% | 1.8 | 30 ft |
| Hancock County | 70 | 1% | 2.2% | 0.3 | 70 ft |
| Kenton County | 70 | 0% | 7.0% | 0.5 | 82 ft |
| Owen County | 50 | 0% | 4.5% | 0.5 | n/a |
| Washington County | 50 | 0% | 1.4% | 2.2 | 25 ft |
| Fleming County | 50 | 0% | 6.8% | 0.9 | n/a |
| Bourbon County | 40 | 0% | 2.0% | 1.6 | 89 ft |
| Estill County | 40 | 0% | 3.2% | 0.2 | 43 ft |
| Henry County | 40 | 0% | 5.3% | 1.6 | n/a |
| Edmonson County | 40 | 0% | 1.9% | 0.9 | 102 ft |
| Anderson County | 30 | 0% | 2.7% | 0.6 | n/a |
| Marion County | 30 | 0% | 1.6% | 2.1 | 20 ft |
| Shelby County | 30 | 0% | 3.6% | 3.4 | n/a |
| Grant County | 20 | 0% | 3.9% | 0.4 | n/a |
| Robertson County | 20 | 1% | 1.6% | 0.4 | n/a |
| Bracken County | 20 | 0% | 2.1% | 0.5 | n/a |
| Nicholas County | 20 | 0% | 3.0% | 1.0 | n/a |
| Mason County | 20 | 0% | 1.9% | 1.6 | n/a |
| Pendleton County | 20 | 0% | 4.6% | 0.3 | n/a |
| Harrison County | 10 | 0% | 2.2% | 1.0 | n/a |
| Carroll County | 10 | 0% | 4.5% | 0.6 | n/a |
| Gallatin County | 10 | 0% | 5.2% | 0.6 | n/a |
Shading: red is among the highest counties nationally, amber the middle, green the lower range. Click a column to sort.
Most well users above the arsenic limit
- Pike County: about 1,300 people
- Bullitt County: about 420 people
- Oldham County: about 420 people
- Lawrence County: about 360 people
- Letcher County: about 330 people
Highest modeled nitrate
- Simpson County: 5.2 mg/L average (limit 10)
- Logan County: 3.5 mg/L average (limit 10)
- Shelby County: 3.4 mg/L average (limit 10)
- Warren County: 3.2 mg/L average (limit 10)
Test first, then treat what the test finds
We may earn a commission from links below, at no cost to you. Picks follow the testing order, not who pays. How we make money.
1. Certified lab well test
Start here, every year
A mail-in kit analyzed by a certified lab measures bacteria, nitrate, arsenic, metals and more. Test strips cannot measure arsenic or uranium reliably.
Mail-in certified lab well water test
Mid-range2. Sediment pre-filter
Sand, silt or cloudy water
A 5-micron cartridge after the pressure tank catches sand, silt and rust before they reach fixtures or other filters. Cartridges are cheap and swap every few months.
5-micron whole-house sediment filter
Budget3. Iron and sulfur filter
Orange stains or rotten-egg smell
Air-injection or oxidizing-media filters remove orange staining and rotten-egg smell. Size one from a lab result for iron, manganese and hydrogen sulfide.
Air-injection iron and sulfur filter
Premium4. UV disinfection system
Coliform bacteria in a test
Inactivates bacteria and viruses; usually for private wells or after boil notices.
12 GPM whole-house UV purifier
Premium5. Under-sink reverse osmosis
Arsenic, nitrate or uranium in a test
The most thorough option for drinking water: PFAS, lead, nitrate, arsenic and more. Look for NSF/ANSI 58.
Waterdrop G3P600 tankless RO
Price at Waterdrop, checked Oct 5, 2026or compare on Amazon
iSpring RCC7AK reverse osmosis
Mid-range6. Whole-house well filter
Several problems at once
Multi-stage sediment and carbon for every tap. Add UV if bacteria shows up, and choose stages from your lab results, not a guess.
Waterdrop WHF21-PG 2-stage whole-house filter
Price at Waterdrop, checked Oct 5, 2026
Questions
Which Kentucky counties rely most on wells?+
By share of homes: Knott County (74%), Letcher County (66%), Hickman County (58%), Carlisle County (57%), Leslie County (54%). By number of people: Pike County (25,700), Letcher County (14,100), Graves County (14,100).
Is arsenic a problem in Kentucky wells?+
USGS estimates about 6,700 Kentucky well users have water above the 10 microgram per liter arsenic limit that applies to public systems, the largest numbers in Pike County, Bullitt County, Oldham County. Arsenic has no taste or smell, so only a lab test finds it.
Do I have to test my well when I sell a house in Kentucky?+
We could not confirm a statewide rule for Kentucky. Check with your county health department. Buyers can still make a lab test a condition of the offer.
How often should I test my well?+
No federal law covers private wells. EPA's drinking water limits apply to public water systems, so testing and treating a private well is up to the owner. EPA and CDC recommend testing at least once a year for coliform bacteria, nitrate, pH and total dissolved solids, and testing for arsenic, uranium, radon and other local concerns based on where you live.
Well-user counts, arsenic and nitrate figures are each a modeled estimate built from national datasets, not a count of tested wells, and well depths summarize drilling records rather than every well. Your own well can be very different from the county average, which is why the only answer for your home is a lab test. Sources: EPA Office of Research and Development, Water Source 2020 (private well estimates by census block); CDC Environmental Public Health Tracking, Well Water Index (from USGS nitrate and arsenic models); USGS, county-level domestic well population with arsenic above 10 micrograms per liter (Ayotte and others, 2017); USGS Synthesized Domestic Well Database for the Conterminous United States (SynDWell-US), McCarthy and others, 2025 (depth, where a county has 30+ usable records).