Why does water hardness vary across Wisconsin?

Water hardness varies across Wisconsin because utilities can use different groundwater wells, reservoirs, treatment plants, blends, and distribution zones. Private wells can also differ from nearby municipal water.

What city in Wisconsin has the hardest water?

Wisconsin Rapids has the hardest water among higher-confidence Wisconsin city pages at 458 PPM. Check the city page for local systems and ZIP codes before making treatment decisions.

Does this include municipal water, well water, or both?

The state report combines public water system records, utility reports, and USGS monitoring where available. Municipal treated-water records are preferred when present. Private well hardness can vary at the address level and should be confirmed with a local test.

How many water systems are in Wisconsin?

Wisconsin has 1,021 active community water systems serving 703 cities.

Water Hardness in Wisconsin

Q: Is Wisconsin water hard or soft?

Wisconsin water is hard on average at 237 PPM (13.8 GPG). Hardness varies by city and water system, so use the city or ZIP page for the best local match.

Average: 237 PPMHard703 cities1,021 water systems

State report

Is Wisconsin Water Hard or Soft?

Wisconsin water is hard on average at 237 PPM (13.8 GPG). Local readings can vary by utility, aquifer, treatment plant, and private well use.

State average

237 PPM

Hard

Local coverage

703 cities

1,021 water systems

Source profile

505 ZIPs

direct or USGS-backed

Wisconsin has mixed source coverage across treated-water records, USGS monitoring, and estimated fallback values.

Methodology Data sources Search by ZIP code

State data profile

How to read the Wisconsin results

State pages are screening and comparison hubs. They summarize ZIP, city, and water-system patterns so you can find the local page that best matches your home or utility.

Direct or USGS-backed ZIPs

505 of 760

66% use treated-water records or USGS monitoring.

Estimated ZIP values

255 ZIPs

34% use nearby, county, or state-level fallback values.

Dataset update

March 9, 2026

Source coverage and rollups are rebuilt from the public dataset.

Use the source coverage below to judge how much local confirmation a specific city or ZIP needs. The methodology page explains the source hierarchy, weighting, and limitations.

State Average

237 PPM

Hard

Coverage

703 cities

1,021 water systems in the state rollup.

Data Source Coverage

ZIP-level source mix for Wisconsin; higher direct and USGS coverage means less reliance on regional estimates.

760 ZIPs covered

Verified treated water

Utility, CCR, or state treated-water records

35%

267 ZIPs

High-confidence USGS

Environmental monitoring matched to local systems

31%

238 ZIPs

Estimated

Nearby, county, or state-level fallback values

34%

255 ZIPs

In Wisconsin, 35% of ZIPs use verified treated-water records, 31% use high-confidence USGS monitoring, and 34% use estimates that should be confirmed locally for treatment decisions.

What the Data Shows in Wisconsin

Hard or very hard water is widespread in Wisconsin, covering 60% of classified ZIPs.

Wisconsin uses a mixed data profile across treated-water records, USGS monitoring, and estimated fallback values.

Use the city table below to compare local results. For estimated locations or unusually high readings, confirm with your utility or a home hardness test before sizing treatment equipment.

ZIP Hardness Distribution

Soft3% (24)

Slightly Hard16% (118)

Moderately Hard21% (159)

Hard11% (84)

Very Hard49% (375)

Treatment Takeaway

For many homes in Wisconsin, hardness is high enough that scale buildup, fixture spotting, and appliance wear are realistic concerns. A local test is the best starting point before sizing a softener.

How to Use This Data

Use the source coverage above to decide how much local confirmation you need for a specific city or ZIP code.

Source-Backed Water Systems in Wisconsin

Large systems with treated-water reports or USGS monitoring behind the state rollup.

Review source labels

Water system	Hardness	Source label	Population
Milwaukee Waterworks WI2410100 - Milwaukee County	140 PPM Moderately Hard	Annual Water Quality Report Verified - Annual Water Quality Report	626,000
Madison Water Utility WI1130224 - Dane County	300 PPM Very Hard	Annual Water Quality Report Verified - Annual Water Quality Report	272,000
Green Bay Waterworks WI4050356 - Brown County	140 PPM Moderately Hard	Annual Water Quality Report Verified - Annual Water Quality Report	107,369
Racine Waterworks WI2520062 - Racine County	140 PPM Moderately Hard	Annual Water Quality Report Verified - Annual Water Quality Report	105,100
Kenosha Water Utility WI2300046 - Kenosha County	140 PPM Moderately Hard	Annual Water Quality Report Verified - Annual Water Quality Report	99,218
Appleton Waterworks WI4450333 - Outagamie County	240 PPM Hard	Annual Water Quality Report Verified - Annual Water Quality Report	74,511
Waukesha Water Utility WI2680238 - Waukesha County	300 PPM Very Hard	Annual Water Quality Report Verified - Annual Water Quality Report	70,718
Eau Claire Waterworks WI6180230 - Eau Claire County	100 PPM Slightly Hard	Annual Water Quality Report Verified - Annual Water Quality Report	70,587

Useful Wisconsin City Pages

Shortcuts to city pages backed by more ZIP-code or water-system data.

Cities With More Local Data

Milwaukee

20 ZIPs · 29 systems

Moderately Hard (140 PPM)

Moderately Hard (140 PPM)

Kenosha

4 ZIPs · 9 systems

Moderately Hard (140 PPM)

Prioritize cities with multiple ZIPs and systems, then use source badges on each city page to separate verified treated-water records from estimates.

Top 10 Hardest Water Cities

#	City	Hardness
1	Wisconsin Rapids	Very Hard (458 PPM)
2	Lake Geneva	Very Hard (416 PPM)
3	Potosi	Very Hard (397 PPM)
4	Hazel Green	Very Hard (395 PPM)
5	Delavan	Very Hard (377 PPM)
6	West Bend	Very Hard (368 PPM)
7	Kewaskum	Very Hard (368 PPM)
8	Plymouth	Very Hard (344 PPM)
9	Lodi	Very Hard (329 PPM)
10	Pewaukee	Very Hard (319 PPM)

Top 10 Softest Water Cities

#	City	Hardness
1	Allouez	Moderately Hard (140 PPM)
2	Ashwaubenon	Moderately Hard (140 PPM)
3	Bay View	Moderately Hard (140 PPM)
4	Cudahy	Moderately Hard (140 PPM)
5	Franklin	Moderately Hard (140 PPM)
6	Green Bay	Moderately Hard (140 PPM)
7	Greendale	Moderately Hard (140 PPM)
8	Greenfield	Moderately Hard (140 PPM)
9	Howard	Moderately Hard (140 PPM)
10	Kenosha	Moderately Hard (140 PPM)

All Cities in Wisconsin

City pages marked Estimated use fallback values and should be confirmed with local testing or utility data.

AbbotsfordSlightly Hard AbramsVery Hard AdamsHard AdellVery Hard AlbanyVery Hard AlgomaVery Hard AllentonVery Hard AllouezModerately Hard AlmaSlightly Hard Alma CenterSoft AlmenaSoft AlmondVery Hard AltoonaSlightly Hard AlvinVery Hard AmbergModerately Hard AmherstVery Hard Amherst JunctionVery Hard AniwaVery Hard AntigoVery Hard AppletonHard ArcadiaSlightly Hard ArenaVery Hard ArgyleVery Hard ArkansawSlightly Hard ArkdaleVery Hard ArlingtonVery Hard Armstrong CreekHard ArpinVery Hard AshippunVery Hard AshwaubenonModerately Hard AthelstaneModerately Hard AuburndaleVery Hard AugustaSlightly Hard AvalonVery Hard AvocaVery Hard BabcockVery Hard BagleyVery Hard Baileys HarborHard BaldwinModerately Hard Balsam LakeModerately Hard BancroftVery Hard BangorHard BarabooModerately Hard BarnesSlightly Hard BarneveldVery Hard BarronSoft BarronettSlightly Hard Bay CityVery Hard Bay ViewModerately Hard BayfieldSlightly Hard Bear CreekHard BeaverModerately Hard Beaver DamVery Hard BeldenvilleVery Hard BelgiumVery Hard BellevilleVery Hard BelmontVery Hard BentonVery Hard BerlinVery Hard Big BendVery Hard BirchwoodSlightly Hard BirnamwoodVery Hard Black EarthVery Hard Black River FallVery Hard BlairSlightly Hard BlanchardvilleVery Hard BloomerModerately Hard BloomingtonVery Hard Blue MoundsVery Hard Blue RiverVery Hard BoscobelVery Hard Boulder JunctionVery Hard BowlerModerately Hard BoycevilleHard BoydModerately Hard BrandonVery Hard BrantwoodVery Hard BriggsvilleVery Hard BrillionVery Hard BristolModerately Hard BrodheadVery Hard BrokawVery Hard BrookfieldVery Hard BrooklynVery Hard BrowntownVery Hard BruceModerately Hard BruleSlightly Hard BrusselsHard BryantHard BurlingtonModerately Hard BurnettVery Hard ButlerVery Hard Butte Des MortsHard ButternutSoft CableSlightly Hard CadottSlightly Hard CaledoniaModerately Hard CambriaVery Hard CambridgeVery Hard CameronSoft CampbellsportVery Hard CantonSlightly Hard CarolineHard CascadeVery Hard CascoHard CashtonSlightly Hard CassvilleVery Hard CatawbaSlightly Hard CavourVery Hard CazenoviaVery Hard CecilHard Cedar GroveVery Hard CedarburgVery Hard Center ValleyHard CenturiaModerately Hard ChaseburgVery Hard ChetekSoft ChiliSlightly Hard ChiltonVery Hard Chippewa FallsModerately Hard Clam FallsModerately Hard Clam LakeSlightly Hard ClaytonModerately Hard Clear LakeModerately Hard ClevelandVery Hard ClintonVery Hard ClintonvilleVery Hard ClymanVery Hard CobbVery Hard ColbySlightly Hard ColemanModerately Hard ColfaxModerately Hard ColgateVery Hard CollinsVery Hard ColomaHard ColumbusVery Hard Combined LocksVery Hard ComstockSlightly Hard ConoverVery Hard ConrathSlightly Hard Coon ValleyVery Hard CornellModerately Hard CornucopiaSlightly Hard Cottage GroveVery Hard CrandonVery Hard Cross PlainsVery Hard Cuba CityVery Hard CudahyModerately Hard CumberlandSoft CurtissModerately Hard CushingSlightly Hard CusterVery Hard CutlerSlightly Hard DairylandSlightly Hard DallasSoft DaltonModerately Hard DaneVery Hard DarienVery Hard DarlingtonVery Hard De ForestVery Hard De PereModerately Hard Deer ParkModerately Hard DeerbrookHard DeerfieldVery Hard DelafieldVery Hard DelavanVery Hard DeltaSlightly Hard DenmarkModerately Hard DerondaModerately Hard DickeyvilleVery Hard DodgeSlightly Hard DodgevilleVery Hard DorchesterSlightly Hard DousmanVery Hard DowningHard DoylestownVery Hard DresserModerately Hard DrummondSlightly Hard DunbarModerately Hard DurandSlightly Hard EagleVery Hard Eagle RiverSoft EarlSlightly Hard East TroyVery Hard EastmanVery Hard Eau ClaireSlightly Hard Eau GalleHard EdenVery Hard EdgertonVery Hard Egg HarborVery Hard ElandVery Hard ElchoVery Hard EldoradoVery Hard ElevaSlightly Hard Elk MoundHard Elkhart LakeVery Hard ElkhornVery Hard Ellison BayVery Hard EllsworthVery Hard Elm GroveVery Hard ElmwoodVery Hard ElroyVery Hard EltonHard EmbarrassVery Hard EndeavorVery Hard EphraimHard EttrickVery Hard EvansvilleVery Hard EvergreenModerately Hard ExelandModerately Hard Fair WaterVery Hard FairchildSlightly Hard Fall CreekSlightly Hard Fall RiverVery Hard FenceVery Hard FennimoreVery Hard FenwoodVery Hard FerryvilleSlightly Hard FifieldSoft Fish CreekHard FitchburgVery Hard FlorenceModerately Hard Fond Du LacVery Hard FontanaVery Hard FootvilleVery Hard Forest JunctionVery Hard ForestvilleHard Fort AtkinsonVery Hard Fountain CitySlightly Hard Fox LakeVery Hard FoxboroSlightly Hard Francis CreekVery Hard FranklinModerately Hard FranksvilleModerately Hard FremontVery Hard FriendshipHard FrieslandVery Hard GalesvilleVery Hard Gays MillsVery Hard GenoaSlightly Hard Genoa CityVery Hard GermantownVery Hard GileSlightly Hard GillettVery Hard GillinghamSlightly Hard GilmanModerately Hard GleasonVery Hard Glen HavenVery Hard GlenbeulahVery Hard Glenwood CityModerately Hard GliddenSlightly Hard GoodmanModerately Hard GordonSlightly Hard GothamVery Hard GraftonVery Hard Grand MarshVery Hard Grand ViewSlightly Hard GrantonVery Hard GratiotVery Hard Green BayModerately Hard Green LakeHard Green ValleyHard GreendaleModerately Hard GreenfieldModerately Hard GreenleafModerately Hard GreenvilleHard GreenwoodSlightly Hard GreshamVery Hard Hager CityVery Hard Hales CornersModerately Hard HamburgVery Hard HammondModerately Hard HancockHard HarshawVery Hard HartfordVery Hard HartlandVery Hard HatleyVery Hard HaugenSlightly Hard HawkinsModerately Hard HawthorneSlightly Hard Hazel GreenVery Hard HazelhurstVery Hard HelenvilleVery Hard HerbsterSlightly Hard HertelSlightly Hard HewittVery Hard High BridgeSlightly Hard HighlandVery Hard HilbertVery Hard HillpointModerately Hard HolcombeModerately Hard HollandaleVery Hard HolmenHard HoriconVery Hard HortonvilleHard HowardModerately Hard Howards GroveVery Hard HubertusVery Hard HudsonModerately Hard HumbirdSlightly Hard HurleySoft HustisfordVery Hard HustlerSlightly Hard IndependenceSlightly Hard IngramModerately Hard IolaVery Hard IrmaSlightly Hard Iron BeltSoft Iron RidgeVery Hard Iron RiverSlightly Hard IxoniaVery Hard JacksonVery Hard JanesvilleVery Hard JeffersonVery Hard Jim FallsModerately Hard Johnson CreekVery Hard JudaVery Hard Junction CityVery Hard JuneauVery Hard KansasvilleModerately Hard KaukaunaVery Hard KellnersvilleVery Hard KendallSlightly Hard KennanModerately Hard KenoshaModerately Hard KeshenaHard KewaskumVery Hard KewauneeVery Hard KielVery Hard KimberlyVery Hard KingstonModerately Hard KnappHard KnowlesVery Hard KohlerVery Hard KrakowHard La CrosseHard La PointeSlightly Hard La ValleModerately Hard Lac Du FlambeauVery Hard LadysmithModerately Hard Lake DeltonModerately Hard Lake GenevaVery Hard Lake MillsVery Hard Lake NebagamonSlightly Hard Lake TomahawkSoft LakewoodHard LancasterVery Hard Land O LakesSoft LannonVery Hard LaonaSlightly Hard LarsenHard LebanonVery Hard LeopolisHard LindenVery Hard Little ChuteHard Little SuamicoHard LivingstonVery Hard LodiVery Hard LoganvilleModerately Hard Lone RockVery Hard LorettaModerately Hard LowellVery Hard LoyalSlightly Hard LublinSlightly Hard LuckModerately Hard LuxemburgVery Hard Lyndon StationSlightly Hard MadisonVery Hard Maiden RockVery Hard MaloneVery Hard ManawaVery Hard Manitowish WaterVery Hard ManitowocVery Hard MapleSlightly Hard MarathonVery Hard MarengoSlightly Hard MaribelVery Hard MarinetteModerately Hard MarionHard MarkesanHard MarquetteModerately Hard MarshallVery Hard MarshfieldVery Hard MaustonSlightly Hard MayvilleVery Hard MazomanieVery Hard Mc FarlandVery Hard MedfordModerately Hard MellenSlightly Hard MelroseVery Hard MenashaHard Menomonee FallsVery Hard MenomonieHard MequonVery Hard MercerSlightly Hard MerrillSlightly Hard MerrillanSlightly Hard MerrimacModerately Hard MiddletonVery Hard MikanaSlightly Hard MilladoreVery Hard MilltownModerately Hard MiltonVery Hard MilwaukeeModerately Hard MindoroHard Mineral PointVery Hard MinocquaSoft MinongSlightly Hard MishicotVery Hard ModenaSoft MonicoSoft MononaVery Hard MonroeVery Hard MontelloHard MontfortVery Hard MonticelloVery Hard MoquahSlightly Hard MorrisonvilleVery Hard MosineeVery Hard Mount CalvaryVery Hard Mount HopeVery Hard Mount HorebVery Hard Mount SterlingVery Hard MountainHard MukwonagoVery Hard MuscodaVery Hard MuskegoVery Hard NashotahVery Hard NavarinoModerately Hard NecedahSlightly Hard NeenahHard NeillsvilleSlightly Hard NekoosaVery Hard NelsonSlightly Hard NeopitHard NeoshoVery Hard NeshkoroVery Hard New AuburnSlightly Hard New BerlinVery Hard New FrankenModerately Hard New GlarusVery Hard New HolsteinVery Hard New LisbonSlightly Hard New LondonVery Hard New PostSlightly Hard New RichmondModerately Hard NewtonVery Hard NiagaraModerately Hard NicholsHard North FreedomModerately Hard North PrairieVery Hard North Woods BeacModerately Hard NorthfieldSoft NorwalkSlightly Hard Oak CreekModerately Hard OakfieldVery Hard OconomowocVery Hard OcontoVery Hard Oconto FallsVery Hard OdanahSlightly Hard OgdensburgVery Hard OgemaSlightly Hard OjibwaSlightly Hard OkaucheeVery Hard OmroHard OnalaskaHard OneidaModerately Hard OntarioVery Hard OostburgVery Hard OregonVery Hard OrfordvilleVery Hard OsceolaModerately Hard OshkoshHard OsseoSlightly Hard OwenModerately Hard OxfordVery Hard PackwaukeeVery Hard PalmyraVery Hard PardeevilleVery Hard Park FallsSoft Patch GroveVery Hard PearsonHard Pelican LakeHard PembineModerately Hard PenceSoft PepinSlightly Hard PeshtigoModerately Hard PewaukeeVery Hard PhelpsSoft PhillipsSoft PickerelHard PickettHard Pigeon FallsSlightly Hard Pine RiverVery Hard PittsvilleVery Hard PlainModerately Hard PlainfieldVery Hard PlattevilleVery Hard Pleasant PrairieModerately Hard PloverVery Hard Plum CityVery Hard PlymouthVery Hard PoplarSlightly Hard Port EdwardsVery Hard Port WashingtonVery Hard Port WingSlightly Hard PortageVery Hard PorterfieldModerately Hard PotosiVery Hard PotterModerately Hard PoundModerately Hard Poy SippiVery Hard PoynetteVery Hard Prairie Du ChienVery Hard Prairie Du SacHard Prairie FarmSlightly Hard PrenticeSlightly Hard PrescottVery Hard PrincetonHard PulaskiModerately Hard RacineModerately Hard RadissonModerately Hard RandolphVery Hard Random LakeVery Hard ReadstownVery Hard RedgraniteVery Hard ReedsburgModerately Hard ReedsvilleVery Hard ReesevilleVery Hard ReweyVery Hard Rib LakeSlightly Hard RichfieldVery Hard RidgelandHard RidgewayVery Hard RingleVery Hard RioVery Hard RiponVery Hard River FallsVery Hard RobertsModerately Hard RochesterModerately Hard Rock SpringsModerately Hard RocklandHard RosendaleVery Hard RosholtVery Hard RothschildVery Hard RubiconVery Hard RudolphVery Hard Saint CloudVery Hard Saint Croix FallModerately Hard Saint FrancisModerately Hard Saint GermainVery Hard Saint JosephModerately Hard Saint NazianzVery Hard SalemModerately Hard SaronaSlightly Hard Sauk CityHard SaukvilleVery Hard SaxonSlightly Hard SaynerVery Hard ScandinaviaVery Hard SchofieldVery Hard SenecaVery Hard SeymourHard SharonVery Hard ShawanoVery Hard SheboyganVery Hard Sheboygan FallsVery Hard SheldonModerately Hard Shell LakeSlightly Hard SherwoodVery Hard ShioctonHard ShopiereVery Hard ShorewoodModerately Hard ShullsburgVery Hard Silver LakeModerately Hard SirenModerately Hard Sister BayHard SlingerVery Hard SobieskiHard Soldiers GroveVery Hard SomersetModerately Hard South ByronVery Hard South MilwaukeeModerately Hard South WayneVery Hard SpartaSlightly Hard SpencerVery Hard SpoonerSlightly Hard Spring GreenModerately Hard Spring ValleyVery Hard SpringfieldVery Hard StanleyModerately Hard Star PrairieModerately Hard StarlakeVery Hard StetsonvilleSlightly Hard SteubenHard Stevens PointVery Hard StilesVery Hard StitzerVery Hard StockbridgeVery Hard StockholmSlightly Hard StoddardVery Hard Stone LakeSlightly Hard StoughtonVery Hard StratfordVery Hard StrumSlightly Hard Sturgeon BayVery Hard SturtevantModerately Hard SuamicoModerately Hard SullivanVery Hard Summit LakeHard Sun PrairieVery Hard SuperiorSlightly Hard SuringVery Hard SussexVery Hard TaylorSlightly Hard TheresaVery Hard ThorpModerately Hard Three LakesSoft TigertonHard TilledaHard TomahawkSlightly Hard TonyModerately Hard TownsendHard TregoSlightly Hard TrempealeauVery Hard TrevorModerately Hard TripoliVery Hard Turtle LakeModerately Hard Twin LakesModerately Hard Two RiversVery Hard Union CenterVery Hard Union GroveModerately Hard UnitySlightly Hard UpsonSlightly Hard ValdersVery Hard Van DyneVery Hard VeronaVery Hard VesperVery Hard VictorySlightly Hard ViolaVery Hard ViroquaVery Hard WabenoSlightly Hard WaldoVery Hard WalesVery Hard WalworthVery Hard WarrensSlightly Hard WashburnSlightly Hard Washington IslanModerately Hard WaterlooVery Hard WatertownVery Hard WaubekaVery Hard WaukauHard WaukeshaVery Hard WaumandeeSlightly Hard WaunakeeVery Hard WaupacaVery Hard WaupunVery Hard WausauVery Hard WausaukeeModerately Hard WautomaHard WauwatosaModerately Hard WauzekaVery Hard WebsterSlightly Hard WentworthSlightly Hard West AllisModerately Hard West BendVery Hard West LimaVery Hard West MilwaukeeModerately Hard West SalemHard WestboroModerately Hard WestbyVery Hard WestfieldHard WeyauwegaVery Hard WeyerhaeuserModerately Hard WheelerHard White LakeHard WhitehallSlightly Hard WhitelawVery Hard WhitewaterVery Hard Wild RoseVery Hard WillardSlightly Hard Williams BayVery Hard WilmotModerately Hard WilsonModerately Hard WiltonSlightly Hard WinchesterVery Hard Wind LakeModerately Hard WindsorVery Hard WinnebagoHard WinneconneHard Wisconsin DellsVery Hard Wisconsin RapidsVery Hard WitheeModerately Hard WittenbergVery Hard WonewocVery Hard WoodmanVery Hard WoodruffSoft WoodvilleModerately Hard WrightstownModerately Hard WyevilleModerately Hard WyocenaVery Hard YubaSlightly Hard ZendaVery Hard