How hard is the water in South Dakota?

The average water hardness across South Dakota is 441 PPM (25.8 GPG), classified as very hard. Hardness varies by city - the hardest higher-confidence city page is Ethan (1862 PPM) and the softest is Isabel (15 PPM).

What city in South Dakota has the hardest water?

Ethan has the hardest water among higher-confidence South Dakota city pages at 1862 PPM. A water softener is recommended for residents.

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 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.

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	Ethan	Very Hard (1862 PPM)
2	Agency Village	Very Hard (1410 PPM)
3	New Effington	Very Hard (1410 PPM)
4	Hermosa	Very Hard (1390 PPM)
5	Lake Andes	Very Hard (1378 PPM)
6	Hot Springs	Very Hard (1358 PPM)
7	Wagner	Very Hard (1339 PPM)
8	Oelrichs	Very Hard (1163 PPM)
9	Dakota Dunes	Very Hard (952 PPM)
10	Oacoma	Very Hard (914 PPM)

Top 10 Softest Water Cities

#	City	Hardness
1	Isabel	Soft (15 PPM)
2	Timber Lake	Soft (17 PPM)
3	Morristown	Soft (28 PPM)
4	Bradley	Slightly Hard (68 PPM)
5	Claire City	Slightly Hard (68 PPM)
6	Lane	Slightly Hard (68 PPM)
7	Ortley	Slightly Hard (68 PPM)
8	Peever	Slightly Hard (68 PPM)
9	Raymond	Slightly Hard (68 PPM)
10	Mc Intosh	Slightly Hard (117 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