Kentucky Water Hardness by County

Water in Kentucky has a median hardness of 120 mg/L as CaCO₃ — "hard" on the USGS scale — based on 28,806 measurements at 4,428 monitoring stations. McLean County has the state's hardest measured water (437 mg/L); Graves County the softest (23.5). Rank: #24 of the 50 states and D.C.

Kentucky water hardness map — what the numbers mean. Data verified 2026-07-22.

Of Kentucky's 104 measured counties, 28 very hard, 32 hard, 35 moderately hard, and 9 soft. The hardest are McLean County (437 mg/L), Jefferson County (395), and Taylor County (315). Graves County is the softest at 23.5 mg/L (soft).

About 74% of Kentucky's roughly 3.7 million residents in counties with gate-passing hardness data live where tap water is hard or worse.

Statewide, Kentucky's median works out to 7 grains per gallon and ranks #24 of the 50 states and D.C. Across 28,806 measurements at 4,428 stations — 10,626 of them since 2000 — the middle 80% of readings fall between 41 and 280 mg/L. The public record runs from 1906 to 2026.

See where Kentucky sits nationally on the national map, or what its number means on the hardness scale.

Download the Kentucky water hardness map (PNG) — Water hardness by county in Kentucky: 104 counties mapped from USGS/EPA data, statewide median 120 mg/L (hard); darker counties have harder water.

By county

Water hardness by county

The table lists all 104 measured Kentucky counties, hardest first. Their medians span 437 mg/L in McLean County to 23.5 in Graves County — a 18.6× range. 16 more Kentucky counties lack gate-passing data.

County water hardness, hardest first — median mg/L as CaCO₃.
CountyMedianBandResultsSitesNewest
McLean County437Very hard42142007
Jefferson County395Very hard1,1481942024
Taylor County315Very hard47242006
Trimble County300Very hard33182005
Metcalfe County295Very hard85652007
Meade County290Very hard2131162019
Campbell County280Very hard51282005
Hopkins County254.5Very hard380662007
Breathitt County253Very hard281382007
Breckinridge County246Very hard117752007
Oldham County240Very hard78202019
Anderson County226Very hard93132007
Shelby County220Very hard86192000
Grant County215.5Very hard38122004
Robertson County211Very hard1542005
Woodford County210Very hard70191999
Bourbon County207.5Very hard162152007
Crittenden County205.5Very hard63282006
Spencer County203Very hard85102007
Christian County200Very hard105462007
Hardin County199Very hard4961812007
Bullitt County197Very hard493202007
Washington County196.5Very hard8862007
Nelson County195Very hard109202005
Caldwell County190Very hard678302023
Logan County184Very hard174542007
Barren County181Very hard91352007
Daviess County180Very hard210812019
Floyd County179.5Hard260262007
Pike County177Hard8621082026
Madison County164Hard149202007
Owen County163Hard88162007
Fulton County160Hard81702014
Larue County160Hard126482006
Martin County160Hard97462007
Warren County159Hard311532007
Marion County157.5Hard1432000
Grayson County155Hard38212007
Garrard County151Hard141162007
Union County150.1Hard265392024
Bath County149Hard97132007
Trigg County149Hard582452023
Estill County148.5Hard150322007
Leslie County145Hard89202007
Green County144Hard418482007
Gallatin County141Hard759192024
Clinton County140Hard141122014
Henderson County140Hard315942007
Muhlenberg County140Hard115352007
Webster County140Hard250292007
Boone County139.6Hard59222016
Butler County136Hard361152007
Bracken County134Hard19792024
Cumberland County132Hard76122005
Hart County130Hard897852007
Henry County130Hard247172004
Hancock County128.5Hard188412024
Lawrence County128Hard391402007
Allen County120Hard202792007
Boyd County120Hard265242007
Franklin County110Moderately hard785252007
Pendleton County110Moderately hard781112007
Greenup County109Moderately hard530282024
Harrison County108.5Moderately hard105132007
Ballard County104Moderately hard143502024
Knox County103Moderately hard36162005
Ohio County103Moderately hard306432007
Elliott County100Moderately hard52122007
Johnson County100Moderately hard182352007
Lee County100Moderately hard191152007
Clay County98Moderately hard164342007
Livingston County98Moderately hard525212024
Wayne County98Moderately hard317192014
Carter County97Moderately hard147202007
Rockcastle County95.8Moderately hard102122007
Casey County95.5Moderately hard842006
Lyon County95.5Moderately hard241192023
Letcher County94Moderately hard1621422007
Pulaski County92Moderately hard550202014
Edmonson County90.8Moderately hard822582007
Powell County90Moderately hard105132007
Fleming County89Moderately hard94432005
Morgan County87.6Moderately hard122162007
Owsley County81.9Moderately hard134102007
Monroe County81.3Moderately hard7442007
Adair County80.8Moderately hard131182007
Jackson County79.8Moderately hard119152007
Russell County76.7Moderately hard200122014
Rowan County75.2Moderately hard38122005
Whitley County73.3Moderately hard812222022
Laurel County71.8Moderately hard429332022
McCracken County65.5Moderately hard540402023
McCreary County64Moderately hard935522014
Marshall County62Moderately hard3371512013
Menifee County62Moderately hard6692007
Harlan County59Soft690512022
Magoffin County55Soft115192000
Bell County49Soft1,9811342007
Lewis County46.1Soft104352019
Wolfe County44Soft99162007
Hickman County34Soft165632007
Carlisle County33.8Soft160472007
Calloway County31Soft2251602009
Graves County23.5Soft3121712018

ZIP codes

ZIP codes in Kentucky

The ZIP codes below are grouped by the Kentucky county they fall in. Each ZIP takes its county's measured median — shown in the group header — so this is a ZIP-to-county guide, not a separate reading for every ZIP. To check the water system serving a specific address, use the lookup.

McLean County · 437 mg/L · Very hard

423224232742350423524237142372

Jefferson County · 395 mg/L · Very hard

4002340025400414011840202402034020440205402064020740208402094021040211402124021340214402154021640217402184021940220402214022240223402284022940231402414024240243402454025840272402804029140299

Taylor County · 315 mg/L · Very hard

427184273342758

Trimble County · 300 mg/L · Very hard

400064004540055

Metcalfe County · 295 mg/L · Very hard

4212442129421544216642214

Meade County · 290 mg/L · Very hard

4010440108401174014240155401574016140175

Campbell County · 280 mg/L · Very hard

410014100741059410714107341074410754107641085

Hopkins County · 254.5 mg/L · Very hard

42408424104241342431424364244042441424424245342464

Breathitt County · 253 mg/L · Very hard

41310413174133941348413664138541390

Breckinridge County · 246 mg/L · Very hard

40111401154011940140401434014440145401464015240170401714017640178

Oldham County · 240 mg/L · Very hard

40010400144002640031400564005940077

Anderson County · 226 mg/L · Very hard

40342

Shelby County · 220 mg/L · Very hard

4000340022400654006740076

Grant County · 215.5 mg/L · Very hard

4101041030410354105241097

Robertson County · 211 mg/L · Very hard

41064

Woodford County · 210 mg/L · Very hard

4034740383

Bourbon County · 207.5 mg/L · Very hard

403484035740361

Crittenden County · 205.5 mg/L · Very hard

4203742064

Spencer County · 203 mg/L · Very hard

4004640071

Christian County · 200 mg/L · Very hard

4221542217422324223642240422544226242266

Hardin County · 199 mg/L · Very hard

40121401604016242701427124272442732427404277642788

Bullitt County · 197 mg/L · Very hard

400474010940110401504016540177

Washington County · 196.5 mg/L · Very hard

40040400614006940078

Nelson County · 195 mg/L · Very hard

4000440008400124001340020400514005240107

Caldwell County · 190 mg/L · Very hard

4241142445

Logan County · 184 mg/L · Very hard

4220242206422564226542276

Barren County · 181 mg/L · Very hard

421234212742130421314214142156

Daviess County · 180 mg/L · Very hard

423014230342355423564236642376

Floyd County · 179.5 mg/L · Hard

41216416014160241603416044160541606416074161241615416164161941621416224163041631416354163641642416454164741649416504165141653416554166041663416664166741669

Pike County · 177 mg/L · Hard

41501415034151241513415144151941522415244152641527415284153141534415354153841539415404154341544415474154841553415544155541557415584155941560415624156341564415664156741568415714157241659

Madison County · 164 mg/L · Hard

40385404034040440475

Owen County · 163 mg/L · Hard

4035540359403634104641098

Fulton County · 160 mg/L · Hard

4204142050

Larue County · 160 mg/L · Hard

4271642748

Martin County · 160 mg/L · Hard

41203412144122441231412504126241267

Warren County · 159 mg/L · Hard

4210142103421044212242159421704217142274

Marion County · 157.5 mg/L · Hard

4000940033400374004940060400624006340328

Grayson County · 155 mg/L · Hard

42721427264275442762

Garrard County · 151 mg/L · Hard

4044440461

Union County · 150.1 mg/L · Hard

42437424594246142462

Bath County · 149 mg/L · Hard

4033440358403604037140374

Trigg County · 149 mg/L · Hard

42211

Estill County · 148.5 mg/L · Hard

4033640472

Leslie County · 145 mg/L · Hard

408034080840816408274084040844408584086840874409794171441749417624176441766417754177641777

Green County · 144 mg/L · Hard

427434276442782

Gallatin County · 141 mg/L · Hard

4108641095

Clinton County · 140 mg/L · Hard

42602

Henderson County · 140 mg/L · Hard

4240642420424514245242458

Muhlenberg County · 140 mg/L · Hard

42321423234232442325423264233042332423374233942344423454236742374

Webster County · 140 mg/L · Hard

42404424094244442450424554245642463

Boone County · 139.6 mg/L · Hard

41005410424104841080410914109241094

Butler County · 136 mg/L · Hard

42252422614227342275

Bracken County · 134 mg/L · Hard

410024100441043

Cumberland County · 132 mg/L · Hard

4271742759

Hart County · 130 mg/L · Hard

4271342722427294274642749427574276542784

Henry County · 130 mg/L · Hard

40007400114001940036400504005740058400684007040075

Hancock County · 128.5 mg/L · Hard

423484235142368

Lawrence County · 128 mg/L · Hard

41124411594118041201412304123241264

Allen County · 120 mg/L · Hard

421204215342164

Boyd County · 120 mg/L · Hard

41101411024112941168

Franklin County · 110 mg/L · Moderately hard

40601

Pendleton County · 110 mg/L · Moderately hard

410064103341040

Greenup County · 109 mg/L · Moderately hard

41121411394114441169411744117541183

Harrison County · 108.5 mg/L · Moderately hard

4100341031

Ballard County · 104 mg/L · Moderately hard

420224202442053420564206042087

Knox County · 103 mg/L · Moderately hard

407344077140903409064091540921409234093540943409464094940953409824099540997

Ohio County · 103 mg/L · Moderately hard

423204232842333423384234342347423494235442361423694237042378

Elliott County · 100 mg/L · Moderately hard

4114941171

Johnson County · 100 mg/L · Moderately hard

4120441219412224122641234412384124041254412554125641257412604126341265412684127141274

Lee County · 100 mg/L · Moderately hard

4131141397

Clay County · 98 mg/L · Moderately hard

40914409414096240972

Livingston County · 98 mg/L · Moderately hard

42028420454204742058420784208142083

Wayne County · 98 mg/L · Moderately hard

425184260342633

Carter County · 97 mg/L · Moderately hard

411324114241143411464116441181

Rockcastle County · 95.8 mg/L · Moderately hard

40409404454045640460

Casey County · 95.5 mg/L · Moderately hard

40437425164252842539425414256542566

Lyon County · 95.5 mg/L · Moderately hard

4203842055

Letcher County · 94 mg/L · Moderately hard

408264086241517415374180441810418124181541819418214182441825418264183241833418354183741838418404184541848418494185541858

Pulaski County · 92 mg/L · Moderately hard

42501425034251942533425444255342567

Edmonson County · 90.8 mg/L · Moderately hard

421604216342207422104225942285

Powell County · 90 mg/L · Moderately hard

403124037640380

Fleming County · 89 mg/L · Moderately hard

41039410414104941093

Morgan County · 87.6 mg/L · Moderately hard

413324135241408414214142541472

Owsley County · 81.9 mg/L · Moderately hard

4098341314413514136441386

Monroe County · 81.3 mg/L · Moderately hard

4213342140421514215742167

Adair County · 80.8 mg/L · Moderately hard

4271542728427414274242753

Jackson County · 79.8 mg/L · Moderately hard

4040240434404474048140486

Russell County · 76.7 mg/L · Moderately hard

4262942642

Rowan County · 75.2 mg/L · Moderately hard

4031340351

Whitley County · 73.3 mg/L · Moderately hard

40701407594076340769

Laurel County · 71.8 mg/L · Moderately hard

4072940737407404074140744

McCracken County · 65.5 mg/L · Moderately hard

420014200342086

McCreary County · 64 mg/L · Moderately hard

42631426344263542638426474264942653

Marshall County · 62 mg/L · Moderately hard

42025420294204442048

Menifee County · 62 mg/L · Moderately hard

40316403224034640387

Harlan County · 59 mg/L · Soft

40801408064080740810408154081840819408204082340824408284082940830408314084340847408494085440855408634086540870408734092740964

Magoffin County · 55 mg/L · Soft

414644146541632

Bell County · 49 mg/L · Soft

4081340845408564090240913409394094040958409654097740988

Lewis County · 46.1 mg/L · Soft

4113541141411664117941189

Wolfe County · 44 mg/L · Soft

413014136041365

Hickman County · 34 mg/L · Soft

4203142032

Carlisle County · 33.8 mg/L · Soft

420214202342035

Calloway County · 31 mg/L · Soft

420204203642049420544207142076

Graves County · 23.5 mg/L · Soft

4202742039420404205142061420664206942079420824208542088

272 ZIP codes are not served by a mapped community water system — most are private-well areas. See well water hardness.

Check any ZIP's utility and hardness →

Source

Groundwater vs surface water

Kentucky's groundwater measures harder than its surface water — 230 mg/L across 4,408 samples versus 116 across 24,075, about 2× harder. Wells draw from groundwater, so well owners in Kentucky tend to see the harder number — 230 mg/L, very hard. Groundwater readings there run 27 to 705 mg/L across the middle 80% of samples. The comparison draws on 2,985 groundwater and 1,426 surface-water monitoring sites; 206 readings above 2,000 mg/L were logged but held out of the medians as outliers.

Groundwater (wells)

230 mg/L as CaCO₃ · 4,408 results at 2,985 stations.

Surface water (rivers, lakes)

116 mg/L as CaCO₃ · 24,075 results at 1,426 stations.

Groundwater measures about 2× harder than surface water here.

Chemistry

Water chemistry in Kentucky

Beyond the hardness number, Kentucky's water carries a fuller chemical signature — here is how its measured parameters compare to national benchmarks.

TDS

148 mg/L · n=2,425

148 mg/L — below the national county median of 226.

pH

7.7 pH · n=3,276

pH 7.7 — within the EPA secondary range of 6.5–8.5, on the alkaline side.

Alkalinity

60 mg/L as CaCO3 · n=4,188

60 mg/L — modest buffering capacity.

Calcium : Magnesium

32.4 : 8 mg/L4.05 : 1 · n=11,904

Calcium is about 71% of Kentucky's hardness (32.4 mg/L Ca to 8 mg/L Mg), a little more calcium-rich than the national ~68% calcium share.

Parameter medians may include a small share of quality-control samples; the hardness lane is fully QC-filtered.

Aquifers

Major aquifers under Kentucky

One aquifer system supply much of Kentucky's measured groundwater.

  • Alluvial aquifersmedian 322 mg/L across 37 samples at 24 sites: very hard.

Together these systems account for 37 measured samples at 24 sites. Aquifer medians pool samples across a whole system and can mask local variation — see the national aquifer map for how these compare across states.

Trend

Hardness over time

1940s2020s410

Kentucky's decade median moved from 410 mg/L in the 1940s to 118 in the 2020s. Over the series, the decade median peaked at 410 mg/L in the 1940s and bottomed at 71 in the 1990s. Decade medians reflect where and what agencies sampled in each era, not just changes in the water itself.

Scale

Where Kentucky sits on the scale

On the USGS scale, Kentucky's 120 mg/L is hard — 7 grains per gallon, above the 120 mg/L hard cutoff, below very hard.

SoftModerately hardHardVery hard60 · 3.5 gpg120 · 7.0 gpg180 · 10.5 gpg120 mg/L — Hard
Harder than 45% of the 2,977 measured county medians.

At 120 mg/L (7 gpg), water-softener owners in Kentucky typically set their unit to this hardness — settings calculator.

Questions

Frequently asked questions

Is Kentucky's water hard?
Kentucky's median hardness is 120 mg/L as CaCO₃, "hard" on the USGS scale and below the national county median of 140 mg/L. About 74% of residents in measured counties have hard-or-worse water.
Which county in Kentucky has the hardest water?
McLean County, with a median of 437 mg/L as CaCO₃ across 42 measurements.
Is well water harder than city water in Kentucky?
Groundwater measures harder here — about 2× the surface water — so wells tend to run harder (groundwater 230 vs surface water 116 mg/L).
How do I find my exact hardness in Kentucky?
Search your ZIP on the lookup tool, read your utility's Consumer Confidence Report, or test at home with a kit.
Is Kentucky's water harder than the national average?
No. Kentucky's median of 120 mg/L is below the national county median of 140 mg/L; it ranks #24 of the 50 states and D.C.

Compare

States with similar hardness

Two states measure closest to Kentucky's 120 mg/L: District of Columbia at 113 mg/L and Idaho at 130 mg/L. Kentucky measures harder than 54% of states. Browse the full ranking on the statistics page.

More: hardness scale · check your address · national statistics · the national map.

By . Source: USGS/EPA Water Quality Portal — 28,806 Kentucky measurements. Data last verified . Methodology.

Cite this page:Kentucky Water Hardness by County.” Hard Water Map. Retrieved 2026-07-22, https://hardwatermap.com/water-hardness/kentucky/