How hard is the water in Denver County, CO?
24.2 grains per gallon
A softener will pay its way here.
The median hardness measured in Denver County, CO is 415 mg/L as calcium carbonate, which is 24.2 gpg. That is very hard on the USGS scale. It comes from 106 samples at 56 sites between 1992 and 2026, drawn from groundwater wells, which is what most taps and private wells in the county draw on.
How much it varies here
Half the sites came in between 19.7 and 29.1 gpg. The whole middle of that range gives the same answer, so a test of your own tap is unlikely to change it. Confidence in the county figure: high (how it is measured).
What to do next
At 24.2 gpg a softener pays its way here. Before you buy, check the quoted unit's grain capacity against the sizing table below, and ask whether it regenerates on demand, which uses less salt than a timer. Call your utility for its own report if you are on city water.
More on sizing a softener for your household.
From 3.3 to 143.0 gpg
The softest single sample on record in Denver County was 57.1 mg/L and the hardest 2,447.3 mg/L, a 43-fold gap. The top quarter of sites read above 29.1 gpg and the bottom quarter below 19.7 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 24.2 gpg, rivers and lakes 14.4 gpg
106 groundwater samples from 56 wells put the median at 415 mg/L. 2,251 surface samples from 81 sites put it at 246 mg/L. In Denver County the wells come out 9.8 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. A utility here that draws from the river can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 32,000-grain unit covers a week between regenerations. Expect about 529 lb of salt a year (14 bags of 40 lb, about $95), and roughly 2,346 gallons of regeneration water. Installed, most units run $1,000 to $4,500; spread over 15 years with salt, that is about $195 a year.
Sizing at 24.2 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,452 | 24,000 | 177 lb |
| 2 | 2,904 | 24,000 | 353 lb |
| 4 | 5,808 | 48,000 | 707 lb |
| 6 | 8,712 | 64,000 | 1,060 lb |
Denver County against the rest of Colorado
Among the 63 Colorado counties with data, Denver County is number 12 of 63 counting from the hardest. Across the whole country it is harder than 91% of counties.
Softest in Colorado: Larimer County at 0.4 gpg. Hardest: Mesa County at 143.7 gpg. Closest to Denver County: Crowley County (23.5), Routt County (23.2), Washington County (22.5).