Water hardness in Idaho

Typical Idaho tap water
118mg/L
6.9gpg
Moderately hard

Population-weighted middle value across 29 Idaho cities in the dataset

People with hard or very hard water
44%
Hardest
Twin Falls 400
Softest
Sandpoint 49

We have hardness numbers for 21 Idaho cities; 6 of them are county estimates rather than utility figures. Each city page adds the water system's EPA violation record and a softener size for a typical household.

Every Idaho city on the hardness scale
SoftModerately hardHardVery hard060120180240300360+Boise City: 90 mg/LMeridian: 86 mg/LNampa: 170 mg/LCaldwell: 170 mg/LIdaho Falls: 173 mg/LPocatello: 351 mg/LCoeur d'Alene: 118 mg/LTwin Falls: 400 mg/LPost Falls: 116 mg/LRexburg: 72 mg/LLewiston: 122 mg/LEagle: 90 mg/LKuna: 90 mg/LMoscow: 111 mg/LStar: 124 mg/LHayden: 118 mg/LChubbuck: 340 mg/LBlackfoot: 119 mg/LRathdrum: 110 mg/LGarden City: 90 mg/LSandpoint: 49 mg/LBoise CityNampaPocatelloSoftMod.HardVery hard060120180240300360+Boise City: 90 mg/LMeridian: 86 mg/LNampa: 170 mg/LCaldwell: 170 mg/LIdaho Falls: 173 mg/LPocatello: 351 mg/LCoeur d'Alene: 118 mg/LTwin Falls: 400 mg/LPost Falls: 116 mg/LRexburg: 72 mg/LLewiston: 122 mg/LEagle: 90 mg/LKuna: 90 mg/LMoscow: 111 mg/LStar: 124 mg/LHayden: 118 mg/LChubbuck: 340 mg/LBlackfoot: 119 mg/LRathdrum: 110 mg/LGarden City: 90 mg/LSandpoint: 49 mg/LBoise CityNampa

Dot size follows population. Tap a dot for the city page.

1Soft
12Moderately hard
5Hard
3Very hard

Hardest water in Idaho

  1. Twin Falls400
  2. Pocatello351
  3. Chubbuck340
  4. Idaho Falls173
  5. Nampa170
  6. Caldwell170
  7. Star124
  8. Lewiston122

Softest water in Idaho

  1. Sandpoint49
  2. Rexburg72
  3. Meridian86
  4. Garden City90
  5. Kuna90
  6. Eagle90
  7. Boise City90
  8. Rathdrum110

All cities in Idaho

Citymg/LgpgClassDataEPA health violations
Boise City905.2Moderately hardUtility report0
Meridian865.0Moderately hardUtility report0
Nampa1709.9HardCounty estimate0
Caldwell1709.9HardCounty estimate0
Idaho Falls17310.1HardUtility report0
Pocatello35120.5Very hardUtility report1
Coeur d'Alene1186.9Moderately hardUtility report0
Twin Falls40023.4Very hardUtility report0
Post Falls1166.8Moderately hardUtility report1
Rexburg724.2Moderately hardCounty estimate1
Lewiston1227.1HardCounty estimate0
Eagle905.3Moderately hardUtility report0
Kuna905.3Moderately hardUtility report0
Moscow1116.5Moderately hardCounty estimate0
Star1247.2HardCounty estimate–
Hayden1186.9Moderately hardUtility report0
Chubbuck34019.9Very hardUtility report0
Blackfoot1197.0Moderately hardUtility report2
Rathdrum1106.4Moderately hardUtility report0
Garden City905.2Moderately hardUtility report0
Sandpoint492.9SoftUtility report1

Questions

Is Idaho water hard?

The typical Idaho resident gets about 118 mg/L (6.9 gpg), which is moderately hard. About 44% of people in the cities we track have hard or very hard water.

Which city in Idaho has the hardest water?

Among 21 cities with pages here, Twin Falls is highest at 400 mg/L.

Which city in Idaho has the softest water?

Sandpoint, at 49 mg/L.

Other states

Hardness data: TapWaterData US Water Hardness, CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.