State water index

Colorado water hardness

Search 58 indexed communities and 161 ZIP profiles, then compare the underlying utility, source, distance, and reporting context.

Median regional evidence

349PPM

Very Hard

Indexed range 7.2–2135 PPM

ZIP profiles: 161
Cities: 58
Matched utilities: 94
Counties: 36

Understanding Colorado

Why local comparisons matter here

Colorado contains high mountain headwaters, Front Range systems, western valleys, and eastern plains aquifers. Elevation and source geology create sharp local contrasts.

In this index, very hard is the largest category, covering 128 of 153 profiles with hardness data. The state median is 349 PPM, but the full indexed range is 7.2–2135 PPM.

State distribution

Hardness across indexed ZIPs

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

Soft · 0–60 PPM13

Moderately hard · 61–120 PPM4

Hard · 121–180 PPM8

Very hard · 181+ PPM128

Evidence coverage

What the current records support

Hardness estimate: 95%
Lead 90th percentile: 98%
Copper 90th percentile: 4%

Low-confidence hardness profiles

Research-comparison eligible profiles

Reported source water

Utility source mix

Surface water: 77
Groundwater: 15
Groundwater influenced by surface water: 2

Highest medians

Highest eligible city medians

Lowest medians

Lowest eligible city medians

City directory

Explore Colorado by city

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

58 cities · 161 ZIP profiles

Search city or county

County

Sort by

58 cities found

Page 1 of 3

Alamosa

Alamosa County · 1 ZIP

—

No regional sampleNo active flag

Arvada

Jefferson County · 5 ZIPs

349PPM regional

Regional range 177.8–349No active flag

Aspen

Pitkin County · 1 ZIP

64PPM regional

County	Median	Range	ZIP profiles
Montezuma County	2135 PPM	2135–2135	1
Logan County	1025 PPM	1024.5–1024.5	1
Otero County	879 PPM	877–881.5	2
Bent County	787 PPM	787–787	1
Delta County	730 PPM	577–882.5	2
Montrose County	609 PPM	568–649	2
Ouray County	577 PPM	576.5–576.5	1
Mesa County	399 PPM	393–405	4
Jefferson County	349 PPM	177.8–349	15
Arapahoe County	349 PPM	349–349	10
Adams County	349 PPM	349–349	12
Broomfield County	349 PPM	349–349	2

Why local comparisons matter here

Hardness across indexed ZIPs

What the current records support

Utility source mix

Highest eligible city medians

Lowest eligible city medians

Explore Colorado by city

Alamosa

Arvada

Aspen

Aurora

Bayfield

Berthoud

Black Hawk

Boulder

Brighton

Broomfield

Burlington

Colorado Springs

Cortez

Craig

Crested Butte

Cripple Creek

Dacono

Delta

Denver

Durango

Englewood

Evans

Florence

Fountain

Highest regional-evidence county medians