Why does water hardness vary across South Dakota?

Water hardness varies across South Dakota 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 South Dakota has the hardest water?

Hot Springs has the hardest water among higher-confidence South Dakota city pages at 1358 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 South Dakota?

South Dakota has 463 active community water systems serving 354 cities.

Water Hardness in South Dakota

Average: 441 PPMVery Hard354 cities463 water systems

State report

Is South Dakota Water Hard or Soft?

South Dakota water is very hard on average at 441 PPM (25.8 GPG). Local readings can vary by utility, aquifer, treatment plant, and private well use.

State average

441 PPM

Very Hard

Local coverage

354 cities

463 water systems

Source profile

126 ZIPs

direct or USGS-backed

65% of covered ZIPs use nearby, county, or state estimates, so confirm local readings before sizing treatment equipment.

Methodology Data sources Search by ZIP code

State data profile

How to read the South Dakota 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

126 of 362

35% use treated-water records or USGS monitoring.

Estimated ZIP values

236 ZIPs

65% 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

441 PPM

Very Hard

Coverage

354 cities

463 water systems in the state rollup.

Data Source Coverage

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

362 ZIPs covered

Verified treated water

Utility, CCR, or state treated-water records

21%

76 ZIPs

High-confidence USGS

Environmental monitoring matched to local systems

14%

50 ZIPs

Estimated

Nearby, county, or state-level fallback values

65%

236 ZIPs

In South Dakota, 21% of ZIPs use verified treated-water records, 14% use high-confidence USGS monitoring, and 65% use estimates that should be confirmed locally for treatment decisions.

What the Data Shows in South Dakota

Hard or very hard water is widespread in South Dakota, covering 82% of classified ZIPs.

South Dakota relies heavily on nearby, county, or state estimates: 65% of ZIPs use fallback values, so local testing matters more here than in states with stronger direct coverage.

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

Soft1% (3)

Slightly Hard3% (10)

Moderately Hard14% (52)

Hard10% (35)

Very Hard72% (262)

Treatment Takeaway

For many homes in South Dakota, 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

Because estimated ZIP values are common in South Dakota, use this page for screening and compare against a utility report or home test before buying equipment.

Source-Backed Water Systems in South Dakota

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

Review source labels

Water system	Hardness	Source label	Population
Sioux Falls SD4600294 - Minnehaha County	250 PPM Very Hard	Annual Water Quality Report Verified - Annual Water Quality Report	216,462
Rapid City SD4600406 - Pennington County	150 PPM Moderately Hard	Annual Water Quality Report Verified - Annual Water Quality Report	72,009
Box Elder SD4600046 - Pennington County	150 PPM Moderately Hard	Annual Water Quality Report Verified - Annual Water Quality Report	14,000
Minnehaha Community Water Corp SD4600432 - Minnehaha County	250 PPM Very Hard	Annual Water Quality Report Verified - Annual Water Quality Report	13,435
Rapid Valley Sanitary District SD4600274 - Pennington County	150 PPM Moderately Hard	Annual Water Quality Report Verified - Annual Water Quality Report	11,408
Brandon SD4600048 - Minnehaha County	250 PPM Very Hard	Annual Water Quality Report Verified - Annual Water Quality Report	11,048
Harrisburg SD4600148 - Lincoln County	250 PPM Very Hard	Annual Water Quality Report Verified - Annual Water Quality Report	10,297
Lincoln County Rural Water System SD4600304 - Lincoln County	250 PPM Very Hard	Annual Water Quality Report Verified - Annual Water Quality Report	5,965

Useful South Dakota City Pages

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

Cities With More Local Data

Moderately Hard (150 PPM)

Moderately Hard (146 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	Hot Springs	Very Hard (1358 PPM)
2	Hereford	Very Hard (597 PPM)
3	Black Hawk	Very Hard (562 PPM)
4	Piedmont	Very Hard (512 PPM)
5	Stockholm	Very Hard (502 PPM)
6	Spearfish Canyon	Very Hard (276 PPM)
7	Sioux Falls	Very Hard (250 PPM)
8	Whitewood	Hard (249 PPM)
9	Deadwood	Hard (242 PPM)
10	Spearfish	Hard (226 PPM)

Top 10 Softest Water Cities

#	City	Hardness
1	Rapid City	Moderately Hard (150 PPM)
2	Hill City	Moderately Hard (152 PPM)
3	New Underwood	Moderately Hard (155 PPM)
4	Colome	Moderately Hard (158 PPM)
5	Wall	Moderately Hard (160 PPM)
6	Britton	Hard (210 PPM)
7	Belle Fourche	Hard (218 PPM)
8	Spearfish	Hard (226 PPM)
9	Deadwood	Hard (242 PPM)
10	Whitewood	Hard (249 PPM)

All Cities in South Dakota

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

AberdeenModerately Hard AcademyEstimatedVery Hard AgarVery Hard Agency VillageVery Hard AkaskaVery Hard AlbeeVery Hard AlcesterVery Hard AllenModerately Hard AlpenaVery Hard AltamontVery Hard AmherstVery Hard AndoverVery Hard ArlingtonVery Hard ArmourVery Hard ArtasVery Hard AstoriaVery Hard AtholVery Hard AuroraVery Hard AvonHard BadgerVery Hard BalticVery Hard BarnardModerately Hard BathModerately Hard Belle FourcheHard BelvidereVery Hard BemisVery Hard BeresfordVery Hard Big Stone CityVery Hard BisonVery Hard Black HawkVery Hard Black Hills StatHard BluntVery Hard BonesteelVery Hard BowdleVery Hard Box ElderModerately Hard BradleySlightly Hard BrandtVery Hard BrittonHard BrookingsVery Hard BruceVery Hard BryantVery Hard BuffaloHard Buffalo GapVery Hard BurbankVery Hard ButlerVery Hard CanistotaHard CanovaEstimatedVery Hard CantonVery Hard CaputaModerately Hard CarpenterVery Hard CarthageVery Hard CastlewoodVery Hard CavourVery Hard CentervilleHard ChamberlainVery Hard ChancellorHard Cherry CreekVery Hard ChesterVery Hard Claire CitySlightly Hard ClaremontModerately Hard ClarkVery Hard ClearfieldModerately Hard ColmanVery Hard ColomeModerately Hard ColtonVery Hard ColumbiaModerately Hard CoronaVery Hard CorsicaVery Hard CorsonVery Hard CottonwoodModerately Hard Crazy HorseVery Hard CresbardVery Hard CrooksVery Hard Dakota DunesVery Hard DallasModerately Hard DanteEstimatedVery Hard DavisHard De SmetVery Hard DeadwoodHard Dell RapidsVery Hard DelmontHard DempsterVery Hard DenbyModerately Hard DimockHard DixonModerately Hard DolandVery Hard DoltonHard DraperVery Hard DupreeModerately Hard Eagle ButteVery Hard EdenVery Hard EdgemontVery Hard EganVery Hard Elk PointVery Hard ElktonVery Hard Ellsworth AfbVery Hard EmeryVery Hard EnningVery Hard ErwinVery Hard EthanVery Hard FairburnVery Hard FairfaxEstimatedVery Hard FairviewVery Hard FaithVery Hard FarmerHard FedoraVery Hard FlandreauVery Hard FlorenceVery Hard ForestburgEstimatedVery Hard Fort PierreVery Hard Fort ThompsonEstimatedVery Hard FrankfortVery Hard FrederickModerately Hard FreemanVery Hard FultonVery Hard Gann ValleyEstimatedVery Hard Garden CityVery Hard GarretsonVery Hard GaryVery Hard GayvilleVery Hard GeddesEstimatedVery Hard GettysburgVery Hard GlenhamVery Hard GrenvilleVery Hard GrotonModerately Hard HamillModerately Hard HarrisburgVery Hard HarrisonHard HarroldVery Hard HartfordVery Hard HayesVery Hard HaytiVery Hard HazelVery Hard HeclaModerately Hard HenryVery Hard HerefordVery Hard HermosaVery Hard HerreidVery Hard HerrickEstimatedVery Hard HighmoreVery Hard Hill CityModerately Hard HitchcockVery Hard HolabirdVery Hard HosmerVery Hard Hot SpringsVery Hard HoughtonModerately Hard HovenVery Hard HudsonVery Hard HumboldtVery Hard HurleyHard HuronVery Hard IdealVery Hard InteriorModerately Hard IpswichVery Hard IreneVery Hard IroquoisEstimatedVery Hard IsabelSoft JavaVery Hard JeffersonVery Hard KadokaSlightly Hard KeldronVery Hard KennebecVery Hard KeystoneModerately Hard KimballVery Hard KranzburgVery Hard KyleModerately Hard La PlantVery Hard LaboltVery Hard Lake AndesVery Hard Lake CityVery Hard Lake NordenVery Hard Lake PrestonVery Hard LaneSlightly Hard LangfordVery Hard LantryVery Hard LebanonVery Hard LennoxVery Hard LeolaVery Hard LestervilleVery Hard LetcherEstimatedVery Hard LilyVery Hard LodgepoleVery Hard Long ValleyModerately Hard LonglakeVery Hard LoomisEstimatedVery Hard Lower BruleVery Hard LucasVery Hard LudlowVery Hard LyonsVery Hard MadisonVery Hard MandersonModerately Hard MansfieldModerately Hard MarionVery Hard MartyEstimatedVery Hard MarvinVery Hard Mc IntoshSlightly Hard Mc LaughlinModerately Hard MeadowVery Hard MelletteVery Hard MennoHard MilbankVery Hard MilesvilleVery Hard MillerVery Hard MirandaVery Hard MissionVery Hard Mission HillVery Hard MobridgeVery Hard MonroeHard MontroseHard MorristownSoft Mound CityVery Hard Mount VernonEstimatedVery Hard Mud ButteVery Hard MurdoModerately Hard NemoHard New EffingtonVery Hard New HollandHard New UnderwoodModerately Hard NewellHard NislandHard NorrisVery Hard NorthvilleVery Hard NundaVery Hard OacomaVery Hard OelrichsVery Hard OglalaModerately Hard OkatonVery Hard OkreekVery Hard OldhamVery Hard OlivetHard OnakaVery Hard OnidaVery Hard OralEstimatedVery Hard OrientVery Hard OrtleySlightly Hard OttumwaSlightly Hard OwankaModerately Hard ParkerVery Hard ParkstonVery Hard ParmeleeVery Hard PeeverSlightly Hard PhilipVery Hard PickstownHard PiedmontVery Hard PierpontVery Hard PierreVery Hard Pine RidgeModerately Hard PlainviewModerately Hard PlankintonEstimatedVery Hard PollockVery Hard PorcupineModerately Hard Prairie CityModerately Hard PreshoVery Hard PringleModerately Hard PukwanaVery Hard RalphVery Hard RamonaVery Hard Rapid CityModerately Hard RaymondSlightly Hard RedfieldVery Hard Ree HeightsVery Hard RelianceVery Hard RennerVery Hard RevaModerately Hard RockhamVery Hard RoscoeVery Hard RosebudVery Hard RosholtVery Hard RoslynVery Hard RoswellEstimatedVery Hard RutlandVery Hard Saint CharlesEstimatedVery Hard Saint FrancisModerately Hard Saint LawrenceVery Hard Saint OngeHard SalemVery Hard ScenicModerately Hard ScotlandVery Hard SelbyVery Hard SenecaVery Hard SinaiVery Hard Sioux FallsVery Hard Sky RanchHard South ShoreVery Hard SpearfishHard Spearfish CanyonVery Hard SpencerHard SpringfieldVery Hard StephanVery Hard StickneyEstimatedVery Hard StockholmVery Hard StonevilleVery Hard StrandburgVery Hard StratfordModerately Hard SummitVery Hard TaborHard TeaHard Timber LakeSoft TolstoyVery Hard TorontoVery Hard Trail CityVery Hard TrentVery Hard TrippVery Hard TulareVery Hard TurtonVery Hard TuthillModerately Hard Twin BrooksVery Hard TyndallHard UticaVery Hard ValeVery Hard Valley SpringsHard VeblenVery Hard VerdonVery Hard VermillionVery Hard VetalModerately Hard ViborgHard ViennaVery Hard VirgilVery Hard VivianVery Hard VolgaVery Hard VolinVery Hard WagnerVery Hard WakondaVery Hard WakpalaVery Hard WalkerVery Hard WallModerately Hard WallaceVery Hard WanbleeModerately Hard WarnerModerately Hard WastaModerately Hard WataugaVery Hard WatertownVery Hard WaubayVery Hard WentworthVery Hard WessingtonVery Hard Wessington SprinVery Hard WetonkaModerately Hard WhiteVery Hard White LakeVery Hard White OwlVery Hard White RiverSlightly Hard WhitehorseVery Hard WhitewoodHard Willow LakeVery Hard WilmotVery Hard WinfredVery Hard WittenVery Hard WolseyVery Hard WoodVery Hard WoonsocketEstimatedVery Hard WorthingVery Hard Wounded KneeModerately Hard YaleVery Hard YanktonVery Hard