Hard Water Map

Tennessee Water Hardness by County

Water in Tennessee has a median hardness of 82.9 mg/L as CaCO₃ — "moderately hard" on the USGS scale — based on 47,207 measurements at 6,452 monitoring stations. Greene County has the state's hardest measured water (246 mg/L); Blount County the softest (8.8). Rank: #29 of the 50 states and D.C.

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

Of Tennessee's 94 measured counties, 9 very hard, 25 hard, 25 moderately hard, and 35 soft. The hardest are Greene County (246 mg/L), Washington County (246), and Hamblen County (230.5). Blount County is the softest at 8.8 mg/L (soft).

About 52% of Tennessee's roughly 7 million residents in counties with gate-passing hardness data live where tap water is hard or worse.

Statewide, Tennessee's median works out to 4.8 grains per gallon and ranks #29 of the 50 states and D.C. Across 47,207 measurements at 6,452 stations — 32,931 of them since 2000 — the middle 80% of readings fall between 13 and 221 mg/L. The public record runs from 1907 to 2025.

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

Download the Tennessee water hardness map (PNG) — Water hardness by county in Tennessee: 94 counties mapped from USGS/EPA data, statewide median 82.9 mg/L (moderately hard); darker counties have harder water.

By county

Water hardness by county

The table lists all 94 measured Tennessee counties, hardest first. Their medians span 246 mg/L in Greene County to 8.8 in Blount County — a 28× range. 1 more Tennessee county lacks gate-passing data.

County water hardness, hardest first — median mg/L as CaCO₃.
CountyMedianBandResultsSitesNewest
Greene County246Very hard771722019
Washington County246Very hard761692019
Hamblen County230.5Very hard36132016
Sullivan County220Very hard1,0151502019
Marshall County208Very hard152472016
Williamson County200Very hard5101062017
Robertson County198Very hard241392018
Rutherford County192Very hard1,3321582018
Maury County180Very hard447732019
Grainger County176Hard79442015
Wilson County170Hard484972018
Hancock County167Hard350472019
Union County163.5Hard82172022
Davidson County160Hard1,219902023
Lincoln County159Hard175512022
Lauderdale County157Hard337642017
Cannon County156Hard202692019
McMinn County155Hard384442022
Bradley County154Hard308552017
Dickson County153Hard393452023
Houston County150Hard6182012
Montgomery County148Hard597452023
Putnam County144Hard4731632020
Anderson County140Hard8931312022
Overton County140Hard353292016
Bedford County130Hard379842019
Cheatham County130Hard544292023
Claiborne County130Hard1,143562019
White County130Hard2431132020
Giles County125Hard275282025
Hawkins County120Hard632722022
Knox County120Hard877602019
Lake County120Hard61282019
Meigs County120Hard173272018
Stewart County115.5Moderately hard196152023
Warren County114Moderately hard355522019
Sequatchie County110Moderately hard179372019
Campbell County105Moderately hard402592019
Macon County105Moderately hard71152015
Hickman County99.7Moderately hard152402014
Jefferson County99.5Moderately hard54122022
Pickett County99.2Moderately hard384152016
Humphreys County99Moderately hard206512019
Sumner County97Moderately hard386322015
Jackson County94.4Moderately hard304172020
Clay County94Moderately hard518182019
Roane County88Moderately hard1,0041182019
Smith County86.7Moderately hard696852020
DeKalb County83.3Moderately hard2,0851642020
Franklin County82.2Moderately hard330902022
Bledsoe County78Moderately hard255592019
Loudon County78Moderately hard522202017
Hamilton County74Moderately hard1,0551752022
Marion County74Moderately hard633772025
Coffee County73Moderately hard4052952022
Rhea County68Moderately hard470722022
Lawrence County65Moderately hard203252024
Moore County64.2Moderately hard38142018
Tipton County61Moderately hard466652019
Grundy County58.5Soft176392019
Shelby County51Soft4,6695742023
Hardin County48Soft367482019
Johnson County47Soft525772018
Wayne County45.5Soft142472019
Crockett County45Soft91292019
Van Buren County41Soft116212018
Perry County40.8Soft25172013
Fentress County40Soft355402016
Sevier County40Soft222432019
Scott County38.7Soft1,486812019
Carter County38Soft492612019
Dyer County38Soft306662019
Cocke County32Soft610332025
Decatur County31.1Soft98242019
Lewis County30.8Soft107212019
Cumberland County26Soft889692019
Obion County26Soft563752019
Henry County24Soft277912022
Monroe County23Soft263422022
McNairy County21Soft265672019
Morgan County21Soft1,5131032019
Polk County20.4Soft1,0221272022
Hardeman County20Soft326642022
Gibson County19.8Soft227592022
Benton County19Soft174252019
Unicoi County19Soft158172022
Haywood County18Soft375502019
Madison County18Soft5181492022
Weakley County18Soft313952019
Fayette County17Soft1,2371182022
Carroll County15.1Soft360792022
Henderson County15Soft342602019
Chester County13Soft91232017
Blount County8.8Soft927802023

ZIP codes

ZIP codes in Tennessee

The ZIP codes below are grouped by the Tennessee county each mostly falls within (by land area). Each ZIP takes that 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.

Key: a † after a ZIP means it has no mapped community water system — usually a private-well area. Plain ZIPs are served by a mapped community water system.

Greene County · 246 mg/L · Very hard

37616376413774337745378093781037818

Washington County · 246 mg/L · Very hard

3760137604376143761537656376593768137690

Hamblen County · 230.5 mg/L · Very hard

3781337814†3786037891

Sullivan County · 220 mg/L · Very hard

3761737618376203766037663376643766537686†

Marshall County · 208 mg/L · Very hard

370193703437047†37091

Williamson County · 200 mg/L · Very hard

37014370273704637062370643706737069371353717938476†

Robertson County · 198 mg/L · Very hard

3701037032370493707337141371463717237188

Rutherford County · 192 mg/L · Very hard

37037370603708537086371183712737128371293713037132371493715337167

Maury County · 180 mg/L · Very hard

371743840138451384743848238487

Grainger County · 176 mg/L · Hard

37708377093784837861†37881†37888

Wilson County · 170 mg/L · Hard

37016370873709037122†37184

Hancock County · 167 mg/L · Hard

37765†37869

Union County · 163.5 mg/L · Hard

377793780737866†

Davidson County · 160 mg/L · Hard

370133707237076370803711537138†371893720137203372043720537206372073720837209372103721137212372133721437215372163721737218372193722037221372283723237238

Lincoln County · 159 mg/L · Hard

37144†373283733437335373483735938449384533845938488

Lauderdale County · 157 mg/L · Hard

3804038041†38063

Cannon County · 156 mg/L · Hard

3702637190†

McMinn County · 155 mg/L · Hard

3730337309†37329†3733137370†37826

Bradley County · 154 mg/L · Hard

3731037311373123732337353

Dickson County · 153 mg/L · Hard

370293703637051†370553716537181†37187

Houston County · 150 mg/L · Hard

370613717537178

Montgomery County · 148 mg/L · Hard

3704037042370433705237142371713719142223†

Putnam County · 144 mg/L · Hard

38501†38503385053850638544†3854838574†38582

Anderson County · 140 mg/L · Hard

3770537710†3771637754377693782837830†

Overton County · 140 mg/L · Hard

3854138542†38543†3855438568†3857038573†38580

Bedford County · 130 mg/L · Hard

37020†371603718037183†37360

Cheatham County · 130 mg/L · Hard

37015370353708237143

Claiborne County · 130 mg/L · Hard

37715†3772437730†37752†3782537851†37870†37879†

White County · 130 mg/L · Hard

385793858338587

Giles County · 125 mg/L · Hard

3845538460384723847338477†38478

Hawkins County · 120 mg/L · Hard

37642376453771137731378113785737873

Knox County · 120 mg/L · Hard

3772137806†378493787137902379093791237914379153791637917379183791937920379213792237923379243792937931379323793437938

Lake County · 120 mg/L · Hard

380773807938080†

Meigs County · 120 mg/L · Hard

37322†37880

Stewart County · 115.5 mg/L · Moderately hard

3702337028†370503705837079†

Warren County · 114 mg/L · Moderately hard

37110†37357373943855038581

Sequatchie County · 110 mg/L · Moderately hard

37327†

Campbell County · 105 mg/L · Moderately hard

37714†37729†37757†377623776637819†37847†

Macon County · 105 mg/L · Moderately hard

3708337150

Hickman County · 99.7 mg/L · Moderately hard

3702537033†370983713737140†38454†

Jefferson County · 99.5 mg/L · Moderately hard

37725†37760†378203787737890†

Pickett County · 99.2 mg/L · Moderately hard

3854938577†

Humphreys County · 99 mg/L · Moderately hard

3707837101†3713437185†

Sumner County · 97 mg/L · Moderately hard

37022370313704837066370753714837186

Jackson County · 94.4 mg/L · Moderately hard

38545385623856438588

Clay County · 94 mg/L · Moderately hard

3855138575

Roane County · 88 mg/L · Moderately hard

37748†37763†37854†

Smith County · 86.7 mg/L · Moderately hard

37030†3714537151†385473855238560385633856738569

DeKalb County · 83.3 mg/L · Moderately hard

37012370593709537166

Franklin County · 82.2 mg/L · Moderately hard

373063731837324†37330373453737537376†3738337398

Bledsoe County · 78 mg/L · Moderately hard

3733837367

Loudon County · 78 mg/L · Moderately hard

377423777137772†3777437846†

Hamilton County · 74 mg/L · Moderately hard

3730237308373153733637341†373433735037351373633737337377373793740237403374043740637407374083740937410374113741237415374163742137450

Marion County · 74 mg/L · Moderately hard

37340373473735637374†37380†37396†3739737405†37419

Coffee County · 73 mg/L · Moderately hard

37018373423735537388†

Rhea County · 68 mg/L · Moderately hard

37321373323733737381†

Lawrence County · 65 mg/L · Moderately hard

3845638457384643846838469384813848338486†

Moore County · 64.2 mg/L · Moderately hard

37352

Tipton County · 61 mg/L · Moderately hard

38004380113801538019380233805872338

Grundy County · 58.5 mg/L · Soft

3730137305373133733937365†37366†37387

Shelby County · 51 mg/L · Soft

3800238016380173801838029380533805438103381043810538106381073810838109381113811238113381143811538116381173811838119381203812238125381263812738128381313813238133381343813538138381393814138152

Hardin County · 48 mg/L · Soft

3832638327383593836138365383703837238376†38475†

Johnson County · 47 mg/L · Soft

37640†37680†37683†37688†37691†

Wayne County · 45.5 mg/L · Soft

38425†38450†38452†38463†38471†38485

Crockett County · 45 mg/L · Soft

3800138021†380343805038337

Van Buren County · 41 mg/L · Soft

3855938585†

Perry County · 40.8 mg/L · Soft

3709637097†

Fentress County · 40 mg/L · Soft

3850438553†38556†38565†38589†

Sevier County · 40 mg/L · Soft

37738†37764†37862378633786537876

Scott County · 38.7 mg/L · Soft

37732†3775537756†378413785237892†

Carter County · 38 mg/L · Soft

3764337658†3768237687†37694†

Dyer County · 38 mg/L · Soft

380073802438030†38047†3805938070

Cocke County · 32 mg/L · Soft

377133772237727377533782137843†

Decatur County · 31.1 mg/L · Soft

3831138329383633837438380†

Lewis County · 30.8 mg/L · Soft

38461†38462

Cumberland County · 26 mg/L · Soft

3772338555†3855838571†3857238578

Obion County · 26 mg/L · Soft

38232†3824038253†38254†38257382593826038261

Henry County · 24 mg/L · Soft

38222†3822438231†38236†3824238251†38256

Monroe County · 23 mg/L · Soft

3735437385†3787437885†

McNairy County · 21 mg/L · Soft

3806138310383153833438339†38357†38367†3837538379

Morgan County · 21 mg/L · Soft

3771937726†37733†37770†3782937840†37845†37872†37887

Polk County · 20.4 mg/L · Soft

373073731637317†373253732637333†373613736237369†37391

Hardeman County · 20 mg/L · Soft

38008†3803938042†38044†38052†38067†38075†38381

Gibson County · 19.8 mg/L · Soft

38233†383163833038338383433835838369†3838238389

Benton County · 19 mg/L · Soft

38221†3832038333†38341

Unicoi County · 19 mg/L · Soft

3765037657†37692†

Haywood County · 18 mg/L · Soft

38006†380123803738069

Madison County · 18 mg/L · Soft

38301†3830538313†38355†38356†38362†38366†38391†38392†

Weakley County · 18 mg/L · Soft

38225†38226†3822938230†3823738241†38255†

Fayette County · 17 mg/L · Soft

38028†380363804638049†38057†3806038066†3806838076†

Carroll County · 15.1 mg/L · Soft

3820138220†38235382583831738318†38321†38342†383443834838387†38390†

Henderson County · 15 mg/L · Soft

3832838345†38351383683837138388†

Chester County · 13 mg/L · Soft

38332†3834038347†38352†

Blount County · 8.8 mg/L · Soft

377013773737777378013780337804†3785337878†37882†37886†

† 178 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

Tennessee's surface water measures harder than its groundwater — 83 mg/L across 43,611 samples versus 77 across 3,471, about 1.1× harder. For well owners that is the better side of a hard bargain: at 77 mg/L, Tennessee groundwater is still moderately hard, and most of the state's drinking water is pumped from it. Groundwater readings there run 14.8 to 308 mg/L across the middle 80% of samples. The comparison draws on 2,354 groundwater and 4,087 surface-water monitoring sites; 21 readings above 2,000 mg/L were logged but held out of the medians as outliers.

Groundwater (wells)

77 mg/L as CaCO₃ · 3,471 results at 2,354 stations.

Surface water (rivers, lakes)

83 mg/L as CaCO₃ · 43,611 results at 4,087 stations.

Surface water measures about 1.1× harder than groundwater here.

Chemistry

Water chemistry in Tennessee

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

TDS

119 mg/L · n=14,913

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

pH

7.5 pH · n=22,800

pH 7.5 — within the EPA secondary range of 6.5–8.5, on the alkaline side.

Alkalinity

76 mg/L as CaCO3 · n=19,563

76 mg/L — modest buffering capacity.

Calcium : Magnesium

26.6 : 4.9 mg/L ≈ 5.43 : 1 · n=16,280

Calcium is about 77% of Tennessee's hardness (26.6 mg/L Ca to 4.9 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 Tennessee

3 aquifer systems supply much of Tennessee's measured groundwater.

  • Mississippi River Valley alluvial aquifer — median 359 mg/L across 28 samples at 13 sites: very hard.
  • Ordovician aquifers — median 230 mg/L across 215 samples at 161 sites: very hard.
  • Alluvial aquifers — median 180 mg/L across 195 samples at 133 sites: very hard.

Together these systems account for 438 measured samples at 307 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

1920s2020s96

Tennessee's decade median moved from 40 mg/L in the 1920s to 73.8 in the 2020s. Over the series, the decade median peaked at 96 mg/L in the 1960s and bottomed at 40 in the 1920s. Decade medians reflect where and what agencies sampled in each era, not just changes in the water itself.

Scale

Where Tennessee sits on the scale

On the USGS scale, Tennessee's 82.9 mg/L is moderately hard — 4.8 grains per gallon, between the 60 and 120 mg/L soft and hard cutoffs.

SoftModerately hardHardVery hard60 · 3.5 gpg120 · 7.0 gpg180 · 10.5 gpg82.9 mg/L — Moderately hard
Harder than 35% of the 2,977 measured county medians.

Questions

Frequently asked questions

Is Tennessee's water hard?
Tennessee's median hardness is 82.9 mg/L as CaCO₃, "moderately hard" on the USGS scale and below the national county median of 140 mg/L. About 52% of residents in measured counties have hard-or-worse water.
Which county in Tennessee has the hardest water?
Greene County, with a median of 246 mg/L as CaCO₃ across 771 measurements.
Is well water harder than city water in Tennessee?
Surface water measures harder here — about 1.1× the groundwater — so wells tend to run softer (groundwater 77 vs surface water 83 mg/L).
How do I find my exact hardness in Tennessee?
Search your ZIP on the lookup tool, read your utility's Consumer Confidence Report, or test at home with a kit.
Is Tennessee's water harder than the national average?
No. Tennessee's median of 82.9 mg/L is below the national county median of 140 mg/L; it ranks #29 of the 50 states and D.C.

Compare

States with similar hardness

Two states measure closest to Tennessee's 82.9 mg/L: Pennsylvania at 83 mg/L and West Virginia at 81 mg/L. Tennessee measures harder than 44% 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 — 47,207 Tennessee measurements. Data last verified . Methodology.

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