How hard is the water in Larimer County, CO?

0.4 grains per gallon

You do not need a softener here.

The median hardness measured in Larimer County, CO is 7 mg/L as calcium carbonate, which is 0.4 gpg. That is soft on the USGS scale. It comes from 1,158 samples at 48 sites between 1990 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 0.2 and 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

You can skip the softener. At 0.4 gpg the most a softener would fix is the odd water spot. If a salesperson in Larimer County says otherwise, ask to see their reading in grains per gallon and compare it with this one.

More on when a softener is not worth it.

From 0.0 to 11.7 gpg

The softest single sample on record in Larimer County was 0.6 mg/L and the hardest 200 mg/L, a 333-fold gap. The top quarter of sites read above 1 gpg and the bottom quarter below 0.2 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.

Wells 0.4 gpg, rivers and lakes 1.8 gpg

1,158 groundwater samples from 48 wells put the median at 7 mg/L. 16,029 surface samples from 354 sites put it at 31 mg/L. In Larimer County the rivers and lakes come out 1.4 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. The two sources are close, so the county figure should hold whichever one your tap is on.

Larimer County against the rest of Colorado

Among the 63 Colorado counties with data, Larimer County is the softest. Across the whole country it is harder than 2% of counties.

Hardest: Mesa County at 143.7 gpg. Closest to Larimer County: Conejos County (3.4), Grand County (4.2), Rio Blanco County (4.3).