Hard Water Map

Indiana Water Hardness by County

Water in Indiana has a median hardness of 280 mg/L as CaCO₃ — "very hard" on the USGS scale — based on 31,097 measurements at 5,980 monitoring stations. Henry County has the state's hardest measured water (374 mg/L); Floyd County the softest (1.8). Rank: #6 of the 50 states and D.C.

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

Of Indiana's 89 measured counties, 75 very hard, 10 hard, 3 moderately hard, and 1 soft. The hardest are Henry County (374 mg/L), Blackford County (373), and Jay County (367). Floyd County is the softest at 1.8 mg/L (soft).

About 96% of Indiana's roughly 6.6 million residents in counties with gate-passing hardness data live where tap water is hard or worse.

Statewide, Indiana's median works out to 16.4 grains per gallon and ranks #6 of the 50 states and D.C. Across 31,097 measurements at 5,980 stations — 11,285 of them since 2000 — the middle 80% of readings fall between 138 and 388 mg/L. The public record runs from 1901 to 2024.

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

Download the Indiana water hardness map (PNG) — Water hardness by county in Indiana: 89 counties mapped from USGS/EPA data, statewide median 280 mg/L (very hard); darker counties have harder water.

By county

Water hardness by county

The table lists all 89 measured Indiana counties, hardest first. Their medians span 374 mg/L in Henry County to 1.8 in Floyd County — a 207.8× range. 3 more Indiana counties lack gate-passing data.

County water hardness, hardest first — median mg/L as CaCO₃.
CountyMedianBandResultsSitesNewest
Henry County374Very hard155232014
Blackford County373Very hard88152013
Jay County367Very hard22972022
Whitley County358.5Very hard7462004
Clinton County348.5Very hard234642004
Madison County342Very hard372402014
Marshall County340Very hard46182004
Wayne County336Very hard313522020
Steuben County333Very hard90262005
Fayette County332Very hard143162004
Benton County331Very hard29152004
Rush County331Very hard133152014
LaGrange County330Very hard19162000
Randolph County330Very hard392372014
Wells County329.5Very hard1042003
Warren County327Very hard190152004
Adams County326Very hard502532004
Delaware County325.5Very hard5121142014
Hamilton County325Very hard147322014
Boone County320Very hard79202014
Grant County319.5Very hard352262004
Montgomery County318.5Very hard372692004
Johnson County316Very hard367202004
Shelby County310Very hard137232014
Tipton County310Very hard50392004
Vermillion County310Very hard581292022
Fountain County309Very hard2972252004
Union County309Very hard15102002
White County309Very hard79122004
Marion County307.5Very hard1,9083102014
Newton County306Very hard308532021
Cass County305.5Very hard430492023
Noble County305Very hard26222003
Carroll County304Very hard336262004
Morgan County303Very hard449512014
Fulton County300Very hard4552912004
Hendricks County300Very hard205322021
Jasper County300Very hard196822021
Pulaski County300Very hard95122004
Tippecanoe County299Very hard552692014
Bartholomew County298.5Very hard298462023
Huntington County298Very hard694112004
Hancock County294Very hard755602023
Howard County293Very hard344962004
Allen County290Very hard912272012
Vigo County290Very hard4012762021
Starke County289.5Very hard96192004
Elkhart County285.5Very hard7101302004
Putnam County285Very hard233382014
Parke County282.5Very hard704522004
Decatur County280Very hard41152023
Franklin County280Very hard325222020
St. Joseph County280Very hard4714292013
Sullivan County280Very hard6411632004
Kosciusko County271Very hard298612004
Knox County270Very hard423842004
Wabash County265Very hard316102004
Porter County264Very hard2,5103552013
Owen County260Very hard233872004
Daviess County252Very hard275372004
Miami County248Very hard333152023
LaPorte County240Very hard2471692023
Pike County231Very hard427392008
Clay County230Very hard8165192004
Greene County227.5Very hard3821472004
Posey County224Very hard335422023
Dearborn County220Very hard205122019
Lawrence County214Very hard732232019
Gibson County212Very hard782422023
Jackson County200Very hard357202013
Ohio County189Very hard6832004
Harrison County188Very hard141112019
Martin County187Very hard189142019
Jennings County182Very hard261252004
Washington County180Very hard153282004
Ripley County178Hard83142004
Orange County170Hard161332002
Spencer County170Hard51382019
Lake County168Hard2,4094842022
Jefferson County160Hard69172019
Monroe County160Hard37132001
Warrick County158Hard232292024
Crawford County152Hard7492004
Scott County149Hard28172002
Perry County130Hard455322023
Clark County103Moderately hard52202019
Dubois County96Moderately hard261612004
Brown County64Moderately hard2992002
Floyd County1.8Soft1252019

ZIP codes

ZIP codes in Indiana

The ZIP codes below are grouped by the Indiana 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.

Henry County · 374 mg/L · Very hard

46148†47337†47344†47351†47352†47356†47360†473614736247366†47384†47385†47386†47387†47388†

Blackford County · 373 mg/L · Very hard

47348†47359

Jay County · 367 mg/L · Very hard

47326†47336†47369†47371†47373†47381†

Whitley County · 358.5 mg/L · Very hard

46723†4672546764†46787†

Clinton County · 348.5 mg/L · Very hard

46035†46039†46041†46050†46057†46058†46065†

Madison County · 342 mg/L · Very hard

46001†46011†46012†46013†4601646017†46036†46044†46048†4605146056†4606346064†46070†

Marshall County · 340 mg/L · Very hard

46501†4650446506†46511†46513†46537†4656346570†46572†

Wayne County · 336 mg/L · Very hard

47324†47327†47330†4733547339†47341†47345†47346†47357†47370†4737447392†47393†

Steuben County · 333 mg/L · Very hard

4670346737†46742†46747†4677646779†

Fayette County · 332 mg/L · Very hard

47331†

Benton County · 331 mg/L · Very hard

47921†47942†47944†47971†47986†

Rush County · 331 mg/L · Very hard

46104†4611546127†46133†46146†46150†46155†46156†46173†

LaGrange County · 330 mg/L · Very hard

4656546571†46746†46761†46771†46786†46789†46795†

Randolph County · 330 mg/L · Very hard

47340†47354†47355†47358†47368†47380†47382†47390†47394

Wells County · 329.5 mg/L · Very hard

4671446731†46759†46766†46770†46777†46778†46781†46791†46799†

Warren County · 327 mg/L · Very hard

47917†47970†47975†47982†47991†47993†

Adams County · 326 mg/L · Very hard

46711†467334674046772†

Delaware County · 325.5 mg/L · Very hard

47302†47303†47304†473054730647320†47334†4733847342†47367†47383†47396†

Hamilton County · 325 mg/L · Very hard

4603046031†460324603346034†460374603846060†4606246069460744628046290

Boone County · 320 mg/L · Very hard

4605246071†46075†460774610246147†

Grant County · 319.5 mg/L · Very hard

46919†46928†46930†4693346938†46952†46953†46957†46986†46987†46989†46991†

Montgomery County · 318.5 mg/L · Very hard

47916†4793347940†47954†47955†4796547967†47968†47989†47990†47994†

Johnson County · 316 mg/L · Very hard

46106†46131461424614346162†4618146184†

Shelby County · 310 mg/L · Very hard

46110†46124†4612646130†46144†46161†4617646182†47234†

Tipton County · 310 mg/L · Very hard

46045†46047†46049†46068†46072†46076†

Vermillion County · 310 mg/L · Very hard

4783147842†47847†47854†478754788447928†4796647974†

Fountain County · 309 mg/L · Very hard

47918†47932†47949†47952†47958†47969†47987†

Union County · 309 mg/L · Very hard

47003†47325†47353†

White County · 309 mg/L · Very hard

47923†47925†47926†47929†47950†47959†47960†47980†47995†

Marion County · 307.5 mg/L · Very hard

4610746183462014620246203462044620546206462084621446216†46217462184621946220462214622246224†462254622646227462284622946235462364623746239462404624146250462544625646259462604626846278

Newton County · 306 mg/L · Very hard

46349†46379†46381†47922†47943†47948†4795147963†47964†

Cass County · 305.5 mg/L · Very hard

46932†4694746950†46961†46967†46978†46988†46994†46998†

Noble County · 305 mg/L · Very hard

46701†46710†46732†4675546760†46763†46767†46784†46794†46796†

Carroll County · 304 mg/L · Very hard

46913†46915†46917†46920†46923†46929†47997†

Morgan County · 303 mg/L · Very hard

461114611346125†46151†46157†46158†46166†46180†

Fulton County · 300 mg/L · Very hard

46910†46922†46931†46939†46945†46975†

Hendricks County · 300 mg/L · Very hard

46103†4611246118†46121†46122†4612346149†46165†46167†461684623146234

Jasper County · 300 mg/L · Very hard

46310†46392†4797747978†

Pulaski County · 300 mg/L · Very hard

46960†46968†46985†46996†47946†47957†

Tippecanoe County · 299 mg/L · Very hard

479014790447905†47906†4790747909†47920†47924†47930†4794147981†47983†47992†

Bartholomew County · 298.5 mg/L · Very hard

47201†47203†47226†47232†47236†47244†4724647247†47280

Huntington County · 298 mg/L · Very hard

46702†4675046783†46792†

Hancock County · 294 mg/L · Very hard

46040†4605546117†4614046154†4616346186†

Howard County · 293 mg/L · Very hard

46901†46902†46936†46937†46965†46979†

Allen County · 290 mg/L · Very hard

46704†46741†46743†46745†46748†46765†46773†46774†4679746798†46802468034680446805468064680746808†46809†46814†4681546816†46818†46819†468254683546845†

Vigo County · 290 mg/L · Very hard

47802†478034780447805†478074780947851†47863†47866†47869†47870478714787647880†47885†

Starke County · 289.5 mg/L · Very hard

46366†46374†46531†46532†46534

Elkhart County · 285.5 mg/L · Very hard

46507465144651646517†46526†46528†4654046543†4655046553†46573†

Putnam County · 285 mg/L · Very hard

461054612046128†46135†46170†46171†46172†46175†

Parke County · 282.5 mg/L · Very hard

47832†47836†47837†47859†478604786247872†47874†

Decatur County · 280 mg/L · Very hard

47225†47240†47263†47272†47283†

Franklin County · 280 mg/L · Very hard

47010†47012†47016†47024†47030†47035†47036†

St. Joseph County · 280 mg/L · Very hard

46530†46536†46544†4654546552†46554†4655646561†46595†46601466134661446615466164661746619†46624†466284663546637†

Sullivan County · 280 mg/L · Very hard

47838†47848†47849†47850†4785547861†4786547879†47882

Kosciusko County · 271 mg/L · Very hard

46502†46508†46510†46524†46538†46539†46542†46555†46562†46567†46580†46582†46590†46982†

Knox County · 270 mg/L · Very hard

4751247516†47524†47528†47535†47557†47561†47573†47578†47591†47596†47597†

Wabash County · 265 mg/L · Very hard

46940†46941†46943†46946†46962†46974†46980†4698446990†46992

Porter County · 264 mg/L · Very hard

46301†46302†4630446341†46347†4636846383†46385†46393†

Owen County · 260 mg/L · Very hard

47427†47431†47433†47455†47456†47460†47868†

Daviess County · 252 mg/L · Very hard

4750147519†47529†47558†47562†47568†

Miami County · 248 mg/L · Very hard

46911†46914†46926†46951†46958†46959†4697046971†

LaPorte County · 240 mg/L · Very hard

46340†46345†4634646348†463504636046365†46371†46382†46390†46391†46574†

Pike County · 231 mg/L · Very hard

47564†47567†4758447585†47590†47598

Clay County · 230 mg/L · Very hard

47833†4783447840†478414784547846†478534785747858†47881

Greene County · 227.5 mg/L · Very hard

47424†474384744147443†4744547449†47453†4745747459†47465†47471†

Posey County · 224 mg/L · Very hard

4762047631†4763347638†

Dearborn County · 220 mg/L · Very hard

47001†47018†47022†47025†47032†47041†47060†

Lawrence County · 214 mg/L · Very hard

4742047421†47436†47437†474464745147462†47467†47470†

Gibson County · 212 mg/L · Very hard

47612†47616†47639†47640†47648†47649†47654†47660†47665†47666†47670†47683†

Jackson County · 200 mg/L · Very hard

4722047229†47235†47260†47264†47274†47281†

Ohio County · 189 mg/L · Very hard

47040†

Harrison County · 188 mg/L · Very hard

47110†4711247114†47115†47117†47135†47136†47142†47160†471614716447166†

Martin County · 187 mg/L · Very hard

47522†47553†47581†

Jennings County · 182 mg/L · Very hard

47223†47227†4726547270†47273†47282

Washington County · 180 mg/L · Very hard

47108†47120†47125†4716547167

Ripley County · 178 mg/L · Hard

47006†47017†47021†47023†47031†470334703447037†47042†

Orange County · 170 mg/L · Hard

47432†47452†47454†47469†

Spencer County · 170 mg/L · Hard

47531†4753747550†47552†47577†4757947588†47611†47615†47634†47635†

Lake County · 168 mg/L · Hard

46303†4630746311463124631946320463214632246323463244632746342†46356†463734637546376†46377†46394464024640346404464054640646407464084640946410

Jefferson County · 160 mg/L · Hard

47138†47224†47230†47231†47243†47250†

Monroe County · 160 mg/L · Hard

47401†4740347404474054740647408†47429474344745847464†47468†

Warrick County · 158 mg/L · Hard

47523†4760147610†47613†47619†4763047637†

Crawford County · 152 mg/L · Hard

47116†47118†47123†47137†47140†47145†47174†47175†

Scott County · 149 mg/L · Hard

4710247170†47177†

Perry County · 130 mg/L · Hard

47514†47515†47520†47525†47551†47574†47576†47586†

Clark County · 103 mg/L · Moderately hard

47104†47106†47111†47126471294713047141†4714347147†47162†47163†47172†

Dubois County · 96 mg/L · Moderately hard

47513†47521†47527†4753247541†475424754647575†47580†

Brown County · 64 mg/L · Moderately hard

46160†461644743547448†

Floyd County · 1.8 mg/L · Soft

47119†47122†47124†47150

† 562 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

Indiana's groundwater measures harder than its surface water — 297 mg/L across 5,734 samples versus 280 across 24,390, about 1.1× harder. Wells draw from groundwater, so well owners in Indiana tend to see the harder number — 297 mg/L, very hard. Groundwater readings there run 95.3 to 500 mg/L across the middle 80% of samples. The comparison draws on 3,671 groundwater and 2,225 surface-water monitoring sites; 116 readings above 2,000 mg/L were logged but held out of the medians as outliers.

Groundwater (wells)

297 mg/L as CaCO₃ · 5,734 results at 3,671 stations.

Surface water (rivers, lakes)

280 mg/L as CaCO₃ · 24,390 results at 2,225 stations.

Groundwater measures about 1.1× harder than surface water here.

Chemistry

Water chemistry in Indiana

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

TDS

294 mg/L · n=2,250

294 mg/L — about 1.3× the national county median of 226, consistent with hard, mineral-rich water.

pH

8 pH · n=2,392

pH 8 — within the EPA secondary range of 6.5–8.5, on the alkaline side.

Alkalinity

177 mg/L as CaCO3 · n=4,487

177 mg/L — substantial buffering capacity, which resists pH swings.

Calcium : Magnesium

62.1 : 21.4 mg/L ≈ 2.9 : 1 · n=3,075

Calcium is about 64% of Indiana's hardness (62.1 mg/L Ca to 21.4 mg/L Mg), a little more magnesium-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 Indiana

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

  • Alluvial aquifers — median 312.5 mg/L across 68 samples at 33 sites: very hard.
  • Sand and gravel aquifers (glaciated regions) — median 310 mg/L across 2,291 samples at 1,087 sites: very hard.
  • Silurian-Devonian aquifers — median 308 mg/L across 96 samples at 73 sites: very hard.

Together these systems account for 2,455 measured samples at 1,193 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

1950s2020s290

Indiana's decade median moved from 280 mg/L in the 1950s to 246.5 in the 2020s. Over the series, the decade median peaked at 290 mg/L in the 1960s and bottomed at 243 in the 2010s. Decade medians reflect where and what agencies sampled in each era, not just changes in the water itself.

Scale

Where Indiana sits on the scale

On the USGS scale, Indiana's 280 mg/L is very hard — 16.4 grains per gallon, well above the 180 mg/L very-hard cutoff — among the hardest water measured in the US.

SoftModerately hardHardVery hard60 · 3.5 gpg120 · 7.0 gpg180 · 10.5 gpg280 mg/L — Very hard
Harder than 79% of the 2,977 measured county medians.

At 280 mg/L (16.4 gpg), water-softener owners in Indiana typically set their unit to this hardness — settings calculator.

Questions

Frequently asked questions

Is Indiana's water hard?
Indiana's median hardness is 280 mg/L as CaCO₃, "very hard" on the USGS scale and 2× the national county median of 140 mg/L. About 96% of residents in measured counties have hard-or-worse water.
Which county in Indiana has the hardest water?
Henry County, with a median of 374 mg/L as CaCO₃ across 155 measurements.
Is well water harder than city water in Indiana?
Groundwater measures harder here — about 1.1× the surface water — so wells tend to run harder (groundwater 297 vs surface water 280 mg/L).
How do I find my exact hardness in Indiana?
Search your ZIP on the lookup tool, read your utility's Consumer Confidence Report, or test at home with a kit.
Is Indiana's water harder than the national average?
Yes. Indiana's median of 280 mg/L is 2× the national county median of 140 mg/L, and Indiana ranks #6 of the 50 states and D.C.

Compare

States with similar hardness

Two states measure closest to Indiana's 280 mg/L: Illinois at 285 mg/L and Ohio at 270 mg/L. Indiana measures harder than 90% 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 — 31,097 Indiana measurements. Data last verified . Methodology.

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