Hard Water Map

Pennsylvania Water Hardness by County

Water in Pennsylvania has a median hardness of 83 mg/L as CaCO₃ — "moderately hard" on the USGS scale — based on 118,614 measurements at 11,936 monitoring stations. Clarion County has the state's hardest measured water (357.5 mg/L); Carbon County the softest (16). Rank: #28 of the 50 states and D.C.

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

Of Pennsylvania's 67 measured counties, 4 very hard, 13 hard, 28 moderately hard, and 22 soft. The hardest are Clarion County (357.5 mg/L), Lebanon County (240), and Clearfield County (198). Carbon County is the softest at 16 mg/L (soft).

About 40% of Pennsylvania's roughly 13 million residents in counties with gate-passing hardness data live where tap water is hard or worse.

Statewide, Pennsylvania's median works out to 4.8 grains per gallon and ranks #28 of the 50 states and D.C. Across 118,614 measurements at 11,936 stations — 81,514 of them since 2000 — the middle 80% of readings fall between 20 and 232 mg/L. The public record runs from 1901 to 2025.

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

Download the Pennsylvania water hardness map (PNG) — Water hardness by county in Pennsylvania: 67 counties mapped from USGS/EPA data, statewide median 83 mg/L (moderately hard); darker counties have harder water.

By county

Water hardness by county

The table lists all 67 measured Pennsylvania counties, hardest first. Their medians span 357.5 mg/L in Clarion County to 16 in Carbon County — a 22.3× range.

County water hardness, hardest first — median mg/L as CaCO₃.
CountyMedianBandResultsSitesNewest
Clarion County357.5Very hard3,5733532025
Lebanon County240Very hard1,0262182025
Clearfield County198Very hard1,7022292025
Lancaster County181Very hard5,1325402025
Cumberland County174Hard1,4722732024
Washington County172Hard8611832025
Beaver County159Hard1,437532025
Centre County154Hard2,6252572025
Greene County152Hard2,1592612025
Lawrence County139Hard1,506482025
Butler County137Hard487522025
Mifflin County134Hard9681472024
Blair County130Hard1,5791632025
Montgomery County129Hard1,7501632025
Berks County120Hard2,3102472025
Erie County120Hard1,6264702025
Philadelphia County120Hard3,9162312025
Jefferson County111.5Moderately hard8341462025
Lehigh County110Moderately hard9581992025
Westmoreland County110Moderately hard1,3041332025
York County100Moderately hard2,9843072025
Allegheny County99Moderately hard3,4351312025
Chester County99Moderately hard6,1011,1242025
Indiana County99Moderately hard1,1004592024
Huntingdon County95Moderately hard1,7001542025
Dauphin County91Moderately hard3,3051822025
Franklin County90Moderately hard5541242024
Mercer County90Moderately hard7281172025
Bucks County88Moderately hard3,1343502025
Perry County88Moderately hard1,8741142024
Delaware County87.7Moderately hard1,241632025
Northumberland County84Moderately hard2,5392022025
Montour County82Moderately hard1,335482024
Lackawanna County81Moderately hard1,002982025
Union County80Moderately hard856502025
Armstrong County78Moderately hard1,522432025
Snyder County78Moderately hard536722025
Luzerne County76Moderately hard1,3812222025
Schuylkill County76Moderately hard5,1163692024
Crawford County73.4Moderately hard1,018752025
Bedford County72Moderately hard1,4581762025
Cambria County70Moderately hard3741112024
Fayette County65Moderately hard2,3371832025
Venango County63Moderately hard1,286492025
Bradford County60Moderately hard1,9092342025
Northampton County58Soft2,227662025
Tioga County58Soft1,5691512025
Susquehanna County57.8Soft7431712025
Wyoming County52Soft1,172782025
Warren County41Soft1,9071302025
Clinton County40.5Soft3,4461832025
Elk County40Soft362962025
Fulton County36Soft488372024
Juniata County36Soft251452023
Columbia County31Soft6021292025
Lycoming County31Soft3,8832492025
Cameron County29Soft1,004492025
Somerset County29Soft2,7132232025
McKean County27Soft1,241422025
Monroe County24Soft1,765832025
Potter County24Soft8981002025
Wayne County23.2Soft2,2782212025
Forest County22Soft821252025
Sullivan County21Soft507552024
Pike County20.4Soft3,2492262025
Adams County18Soft4881152025
Carbon County16Soft950392025

ZIP codes

ZIP codes in Pennsylvania

The ZIP codes below are grouped by the Pennsylvania 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.

Clarion County · 357.5 mg/L · Very hard

16036†16049†1605416213†1621416220†16224†16230†16232†16233†16235†16242†1624816254†16255†16258†16260†16326†16331†16332†16334†16361†

Lebanon County · 240 mg/L · Very hard

17003†170101701617026†17028†17038†17039†17041†1704217046†17064†17067†17073†17077†1707817088

Clearfield County · 198 mg/L · Very hard

1572115753†15757†15801†1584815849†1585615866†166161662016627†16645†1665116656†16661†16666†166711668016692†16821†1682516830†16833†1683416836†1683716838†1683916840168431684716849†1685516858†1686016861†16863†1687616878†1687916881†

Lancaster County · 181 mg/L · Very hard

170221750117502†1750417505†1750617507†1750817509†1751217516†17517†17518†17519†175201752217527†17529†17532†17534†17535†17536†1753817540†17543†17545†175471755017551†175521755417555†1755717560†17562†17563†17565†17566†17568†17569†17570†17572†1757617578†17579†1758117582†17584†1760117602176031760619501

Cumberland County · 174 mg/L · Hard

17007†1701117013†17015170251702717043170501705517065†17081†1709317240†1724117257†17266†17324†

Washington County · 172 mg/L · Hard

1500415019†15021†1502215033150381505315054†150551505715060†1506315067150781530115311†15312†1531315314153171532115323†1532415329†15330†153311533215333†153401534215345†153471534815350153581536015361†1536315365†15366†153671536815376†15377†153781537915412†154171541915423†15427†154291543215434†15477†15483†

Beaver County · 159 mg/L · Hard

15001†1500315005150091501015026†1502715042†15043†15050†15052150591506115066†15074†15077†1508116115†16123†16136

Centre County · 154 mg/L · Hard

16677†16801168021680316820†16823†16826†16827†16828†16829†16832†1683516841†16844†16845†1685116852†16853168541685616859†16864†16865†16866168681687016872†16874†16875†16877†16882†

Greene County · 152 mg/L · Hard

15310†1531515316†15320†1532215325153271533415337†1533815341†1534415346153491535115352†15353153571535915362153641537015380†

Lawrence County · 139 mg/L · Hard

16101†16102†1610516112†16116†16117†16120†16132†16140†16141†16143†16155†16156†16157†1616016172

Butler County · 137 mg/L · Hard

16001†16002†16020†16022†16023†16024†16025160271602916030†16033†16034†16035†16037†16038†16040†16041†1604516046†16048†16050†16051†16052†16053†1605516056†16057†16059†16061†16063†16066

Mifflin County · 134 mg/L · Hard

17004†170091702917044†17051†17054†17063†1707517084†1709917841†

Blair County · 130 mg/L · Hard

16601166021661716625†16631†16635†16637†16648†16662†1666516673†16682166841668616693†

Montgomery County · 129 mg/L · Hard

1804118054†1807018073†18074†18076189151893618964189691900119002190041900619009†19012190251902719031†19034†19035190381904019044190461906619072190751909019095190961940119403194051940619422194261942819435†19436194371943819440194441944619453194541945619462194641946819472†19473†1947419477194901949219525

Berks County · 120 mg/L · Hard

17087†18011†18056†19503†19504†19505†19506†19507†19508†1951019511†19512†19516†195181952219523†19526†19529†19530†19533†19534†19535†1953619538†1953919540†19541†19543†19544†1954519547†19550†19551†19554†19555†19559†19560†1956219564†1956519567†1960119602196041960519606†19607†19608†1960919610†19611

Erie County · 120 mg/L · Hard

16401†16407†16410†16411†1641216415†16417†16421†1642316426†16427†16428†16430†1643816441†16442†16443†1644416475†1650116502165031650416505†1650616507165081650916510†16511165461655016563

Philadelphia County · 120 mg/L · Hard

19102191031910419106191071910819109191111911219114191151911619118191191912019121191221912319124191251912619127191281912919130191311913219133191341913519136191371913819139191401914119142191431914419145191461914719148191491915019151191521915319154

Jefferson County · 111.5 mg/L · Moderately hard

15711†15715†15730†1573315744†15764†15767†15770†15776†15778†15780†15781†15784†15824†15825†15829†15840†1584715851†15860†15863†15864†1586516240†

Lehigh County · 110 mg/L · Moderately hard

1801818031†18032180341803618037†1804618049†180511805218053†18059†18062†18065†18066†18069†180781807918080†1808718092†18101181021810318104181061810918195

Westmoreland County · 110 mg/L · Moderately hard

15012150621506815072150831508515087150891544815479156011561015611156121561315615156161561715619156201562315624156251562615627156281562915632156331563415635156361563715638156391564015641156421564415646156471565015655†1565615658†156601566115662156631566515666†1566815670†156711567215674156751567615677†156781567915680156831568415687†15688156891569115692156931569515696156971569815779†1592315944

York County · 100 mg/L · Moderately hard

170191707017302†17309†1731117313†17314†17315†17317173181731917321†17322†1732317327†17329†1733117339†1734217345173471734917352†17355173561736017361173621736317364†17365†17366†1736817370†1737117401174021740317404174061740717408

Allegheny County · 99 mg/L · Moderately hard

150061500715014150151501715018†15020150241502515028150301503115034150351503715044150451504615047150491505115056150641506515071150751507615082150841508615088150901510115102151041510615108151101511215116151201512215123†15126†1512915131151321513315135†151361513715139151401514215143151441514515146151471514815201152021520315204152051520615207†152081520915210152111521215213152141521515216152171521815219152201522115222†152231522415225152261522715228152291523215233152341523515236152371523815239152411524315260152751528215290

Chester County · 99 mg/L · Moderately hard

190871930119310†193111931219316†19317†19320†19330†1933319335†1934119343†19344†19345†1934819350†19352†1935519358†19362†1936319365†1936719369193721937419375†19380†19382193831939019425†19442194571946019465†19475†19520†

Indiana County · 99 mg/L · Moderately hard

15681157011570515710†15712†15713†15716157171572015723†15724†1572515727†15728†15729†1573115732†15734†1573915741†15742†1574515746†1574715748†15750157521575415756†15759†15761†15763†15765†15771†15772†15777†157831592015929159491595415957†1596116211†1624616256†

Huntingdon County · 95 mg/L · Moderately hard

16611†16621†16622†16623†16634†16638†16647†16652†1665416657†16669†16674†16683†16685†16694†17002†17052†17060†17066†17213†17215†17239†17243†172491725317255†17260†17264†

Dauphin County · 91 mg/L · Moderately hard

17005†17018†17023†17030†17032†170331703417036†17048†1705717061†170801709717098†1710117102171031710417109171101711117112†171131712017978†17980†

Franklin County · 90 mg/L · Moderately hard

172011720217210†17214†17217†17219†17220†17221†17222†17224†17225†17232†1723517236†17237†17244†17246†172471725017251†172521725417261†17262†17263†17265†17268†17271†

Mercer County · 90 mg/L · Moderately hard

16113†16114†1612116124†1612516127†16130†16133†1613716142†16145†161461614816150†16151†16153†16154†16159†1616116311†

Bucks County · 88 mg/L · Moderately hard

18077†18081†189011890218912†18913†189141891718920†18921†18923†18925†18927†1892918930†18932†18933†1893518938†1894018942†18944†18946†18947†18950†1895118954189551896018962189661897018972†189741897618977†18980†1900719020190211903019047190531905419055190561905719067

Perry County · 88 mg/L · Moderately hard

17006†17020†17024†17037†17040†17045†17047†17053†17062†17068†17069†17071†17074†17090†

Delaware County · 87.7 mg/L · Moderately hard

19003190081901019013190141901519017†1901819022†19023190261902919032190331903619041190431905019052190601906119063190641907019073†1907419076190781907919081190821908319085190861909419113193191934219373

Northumberland County · 84 mg/L · Moderately hard

17017†1773017749†17777†17801†17823†17830†17832†17834†17836†17840†17847†1785017851†17857†17860†17865†1786617867†17868†17872†17881†

Montour County · 82 mg/L · Moderately hard

17772†1782117822†17884†

Lackawanna County · 81 mg/L · Moderately hard

1840318407†18411†1841418420†18424†18433†1843418440†18444†18447†18452184711850318504185051850718508185091851018512†185171851818519

Union County · 80 mg/L · Moderately hard

17829†17835†17837†17844†17845†17855†17856†17880†17885†1788617887

Armstrong County · 78 mg/L · Moderately hard

15618†1567315682†15686†15690†15736†15774†16028†16201†162101621216218†16222†16223†16226†162281622916236†1623816244†16245†16249†16250†1625316259†16262†16263

Snyder County · 78 mg/L · Moderately hard

17086†17812†17813†17827†17842†17853†17861†1786217864†178701787617889†

Luzerne County · 76 mg/L · Moderately hard

18201†18202†1821918221†18222†18223†18224†18225182341823918241†18246†18249†18256†18602†186121861718618†18621†18622†18627†1863418635†18640186411864218643†18644†18651†18655†18656†18660†18661†1870118702†18704187051870618707†1870818709

Schuylkill County · 76 mg/L · Moderately hard

1790117921†17922†17923†179251792917930†1793117933†17934†179351793617938†17941†17943†17944†17946†17948179491795117952†17953†179541795717959†17960†17961†1796317964†1796517967†17968†1797017972†179741797617979†1798117982†1798317985†18211†18214†18218182201823118237†1824218245†18248†18252†19549†

Crawford County · 73.4 mg/L · Moderately hard

16110†16111†16131†16134†16314†16316†16327†16328†1633516360†16403†16404†1640616422†16424†16433†16434†16435†16440†

Bedford County · 72 mg/L · Moderately hard

15521†15522†15533†15534†15535†15537†15539†15545†15550†15554†15559†16633†16650†16655†16659†16664†16667†16670†16672†16678†16679†16695†17211†

Cambria County · 70 mg/L · Moderately hard

15714†15722†15737†15738†15760†15762†1577315775†159011590215904159051590615909†15921159221592515927†1593015931†159341593815940†15942†159431594515946†159481595115952159551595615958†15960†1596216613†1661916624†1663016636†16639†1664016641†16646†16668†16675†16699

Fayette County · 65 mg/L · Moderately hard

15401†1541015413†154161542015421†1542215425†154281543015431†154331543515436†15437†1543815440†15442154431544415445†1544615447154491545015451154541545515456†1545815459†154601546115462154631546415465†1546615467154681546915470†154721547315474154751547615478†154801548215484†1548615488154891549015492†1562215631

Venango County · 63 mg/L · Moderately hard

16301†16317†16319†1632316341†16342†16343†1634416346†16354†16362†16364†1637216373†16374†

Bradford County · 60 mg/L · Moderately hard

16910†16914†16925†16926†16947†17724†18623†18810†18814†18817†1882918831†18832†18833†18837†1884018845†18846†18848†18850†18851†18853†18854†

Northampton County · 58 mg/L · Soft

18013†18014†18015180171802018035†18038†18040180421804518055†180631806418067†18072†18083180851808618088†18091†18343†18351

Tioga County · 58 mg/L · Soft

1690116911†16912†16917†16920†16921†16928†16929†16930†16932†16933†16935†16936†16938†169391694016942†16946†16950†17727†17765†

Susquehanna County · 57.8 mg/L · Soft

18413†18421†18430†18441†18446†18465†18470†18630†18801†18812†18816†18818†18820†18821†18822†18823†18824†18825†18826†18828†18830†18834†18842†18843†18844†18847†

Wyoming County · 52 mg/L · Soft

18419†18615†18625†18629†18636†18657†

Warren County · 41 mg/L · Soft

16312†16313†16329†16340†16345†16347†16350†16351†16352†1636516371†16402†16405†16416†16420†16436†

Clinton County · 40.5 mg/L · Soft

16822†1684816871†1772117745†17747†1774817750†17751†17760†17764†17778†17779

Elk County · 40 mg/L · Soft

15821†15823†158271583115841†15845†15846†15853†15857†15868†15870†16734†

Fulton County · 36 mg/L · Soft

15536†16689†16691†17212†17223†17228†17229†17233†17238†17267†

Juniata County · 36 mg/L · Soft

17014†17021†17035†17049†17056†17058†17059†17076†17082†17094†

Columbia County · 31 mg/L · Soft

17814†17815†17820†17824†17846†17858†17859†17878†17888†17920†17945†18603†18631

Lycoming County · 31 mg/L · Soft

17701†17702†17720†17723†17728†17737†17739†17740†17742†17744†17752†17754†17756†17762†17763†17769†17771†17774†17776†17810†

Cameron County · 29 mg/L · Soft

15832†15834†15861†

Somerset County · 29 mg/L · Soft

15411†15424†15501†15502†1551015520†15530†15531†15532†15538†15540†15541†15542†15544155461554715551†15552†1555515557†15558†15560†1556115562†15563†15564†15565†15924†15926†159281593515936†15937†15953†15963†

McKean County · 27 mg/L · Soft

16333†16701†1672416725†16726†16727†16729†16730†16731†16732†16733†16735†16738†16740†16743†16744†16745†16749†16750†

Monroe County · 24 mg/L · Soft

18058†18301†18302†18321†18322†18323†18325†18326†1832718330†18331†18332†18333†18334†1833518342†18344†18346†18347†18349†18350†18353†18354†18355†18356†18357†18360†18370†18372†1846618610†

Potter County · 24 mg/L · Soft

16720†16746†16748†16915†16922†16923†16927†16937†16941†16943†16948†17729†

Wayne County · 23.2 mg/L · Soft

18405†18415†18417†18431†18436†18437†18438†18439†18443†18445†18453†18454†18455†18456†18460†18461†18462†18463†18469†1847218473†

Forest County · 22 mg/L · Soft

15828†16217†16239†16321†16322†16353†16370†

Sullivan County · 21 mg/L · Soft

17731†17758†17768†18614†18616†18619†18626†18628†18632†

Pike County · 20.4 mg/L · Soft

18324†18328†18336†18337†18340†1837118425†18426†18428†18435†18451†18457†18458†18464†

Adams County · 18 mg/L · Soft

173011730317304†1730617307†17316†173201732517340†17343†1734417350†17353†17372†

Carbon County · 16 mg/L · Soft

18012†1803018071†18210†18212†18216†18229†18230†18232182351824018244†18250†18254†1825518624†

† 1,019 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

Pennsylvania's groundwater measures harder than its surface water — 140 mg/L across 13,139 samples versus 79 across 105,214, about 1.8× harder. Wells draw from groundwater, so well owners in Pennsylvania tend to see the harder number — 140 mg/L, hard. Groundwater readings there run 34 to 744 mg/L across the middle 80% of samples. The comparison draws on 6,492 groundwater and 5,403 surface-water monitoring sites; 656 readings above 2,000 mg/L were logged but held out of the medians as outliers.

Groundwater (wells)

140 mg/L as CaCO₃ · 13,139 results at 6,492 stations.

Surface water (rivers, lakes)

79 mg/L as CaCO₃ · 105,214 results at 5,403 stations.

Groundwater measures about 1.8× harder than surface water here.

Chemistry

Water chemistry in Pennsylvania

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

TDS

138 mg/L · n=58,446

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

pH

7.6 pH · n=81,097

pH 7.6 — within the EPA secondary range of 6.5–8.5, on the alkaline side.

Alkalinity

44 mg/L as CaCO3 · n=78,423

44 mg/L — modest buffering capacity.

Calcium : Magnesium

17.8 : 5.2 mg/L ≈ 3.42 : 1 · n=97,797

Calcium is about 67% of Pennsylvania's hardness (17.8 mg/L Ca to 5.2 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 Pennsylvania

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

  • Piedmont and Blue Ridge carbonate-rock aquifers — median 305 mg/L across 536 samples at 326 sites: very hard.
  • Pennsylvanian aquifers — median 210 mg/L across 2,461 samples at 1,154 sites: very hard.
  • Early Mesozoic basin aquifers — median 160 mg/L across 832 samples at 599 sites: hard.

Together these systems account for 3,829 measured samples at 2,079 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

1920s2020s140

Pennsylvania's decade median moved from 140 mg/L in the 1920s to 81 in the 2020s. Over the series, the decade median peaked at 140 mg/L in the 1920s and bottomed at 73 in the 2000s. Decade medians reflect where and what agencies sampled in each era, not just changes in the water itself.

Scale

Where Pennsylvania sits on the scale

On the USGS scale, Pennsylvania's 83 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 gpg83 mg/L — Moderately hard
Harder than 35% of the 2,977 measured county medians.

Questions

Frequently asked questions

Is Pennsylvania's water hard?
Pennsylvania's median hardness is 83 mg/L as CaCO₃, "moderately hard" on the USGS scale and below the national county median of 140 mg/L.
Which county in Pennsylvania has the hardest water?
Clarion County, with a median of 357.5 mg/L as CaCO₃ across 3,573 measurements.
Is well water harder than city water in Pennsylvania?
Groundwater measures harder here — about 1.8× the surface water — so wells tend to run harder (groundwater 140 vs surface water 79 mg/L).
How do I find my exact hardness in Pennsylvania?
Search your ZIP on the lookup tool, read your utility's Consumer Confidence Report, or test at home with a kit.
Is Pennsylvania's water harder than the national average?
No. Pennsylvania's median of 83 mg/L is below the national county median of 140 mg/L; it ranks #28 of the 50 states and D.C.

Compare

States with similar hardness

Two states measure closest to Pennsylvania's 83 mg/L: Tennessee at 82.9 mg/L and West Virginia at 81 mg/L. Pennsylvania measures harder than 46% 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 — 118,614 Pennsylvania measurements. Data last verified . Methodology.

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