State water index

Idaho water hardness

Search 67 indexed communities and 78 ZIP profiles, then compare the underlying utility, source, distance, and reporting context.

Median indexed hardness

168PPM

Hard

Indexed range 22.2–339 PPM

ZIP profiles: 78
Cities: 67
Matched utilities: 79
Counties: 36

Understanding Idaho

Why local comparisons matter here

Idaho includes mountain watersheds, the volcanic Snake River Plain, agricultural valleys, and northern lake and river systems. Groundwater and surface-water settings vary widely.

In this index, very hard is the largest category, covering 37 of 78 profiles with hardness data. The state median is 168 PPM, but the full indexed range is 22.2–339 PPM.

State distribution

Hardness across indexed ZIPs

Counts describe published ZIP profiles, not a population-weighted statewide sample.

Soft · 0–60 PPM9

Moderately hard · 61–120 PPM22

Hard · 121–180 PPM10

Very hard · 181+ PPM37

Evidence coverage

What the current records support

Hardness estimate: 100%
Lead 90th percentile: 100%
Copper 90th percentile: 8%

Low-confidence hardness profiles

Nearest site more than 25 miles away

Reported source water

Utility source mix

Groundwater: 69
Surface water: 9
Groundwater influenced by surface water: 1

Highest medians

Hardest indexed cities

1. Franklin339 PPM
2. Dayton269 PPM
3. Preston263 PPM
4. American Falls245 PPM
5. Aberdeen233 PPM

Lowest medians

Softest indexed cities

City directory

Explore Idaho by city

Search by city or county, then sort by name, hardness, or ZIP coverage.

67 cities · 78 ZIP profiles

Search city or county

County

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67 cities found

Page 1 of 3

Aberdeen

Bingham County · 1 ZIP

233PPM

County	Median	Range	ZIP profiles
Franklin County	269 PPM	263–339	4
Power County	245 PPM	244.5–244.5	1
Bannock County	232 PPM	230–233	2
Cassia County	228 PPM	228–228	1
Butte County	226 PPM	226–226	1
Twin Falls County	226 PPM	225–228	5
Minidoka County	226 PPM	225–228	3
Gooding County	225 PPM	225–225	2
Jerome County	225 PPM	225–225	1
Lincoln County	224 PPM	224–224	1
Bingham County	211 PPM	189–232.5	2
Blaine County	210 PPM	173–217	4

Why local comparisons matter here

Hardness across indexed ZIPs

What the current records support

Utility source mix

Hardest indexed cities

Softest indexed cities

Explore Idaho by city

Aberdeen

American Falls

Ammon

Arco

Bonners Ferry

Buhl

Burley

Caldwell

Cascade

Dayton

Driggs

Eagle

Emmett

Filer

Franklin

Fruitland

Genesee

Glenns Ferry

Gooding

Grangeville

Hailey

Hansen

Heyburn

Homedale

Highest indexed county medians