How hard is the water in Colusa County, CA?
14.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Colusa County, CA is 249 mg/L as calcium carbonate, which is 14.5 gpg. That is very hard on the USGS scale. It comes from 40 samples at 17 sites between 1996 and 2025, 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 10.3 and 22 gpg. That spread crosses a decision line, so some homes here land on a different answer. A $10 test strip on your own tap settles it. Confidence in the county figure: high (how it is measured).
What to do next
At 14.5 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. Because Colusa County straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on sizing a softener for your household.
From 5.5 to 41.5 gpg
The softest single sample on record in Colusa County was 94 mg/L and the hardest 710 mg/L, an 8-fold gap. The top quarter of sites read above 22 gpg and the bottom quarter below 10.3 gpg.
Wells 14.5 gpg, rivers and lakes 26.1 gpg
40 groundwater samples from 17 wells put the median at 249 mg/L. 51 surface samples from 6 sites put it at 446.4 mg/L. In Colusa County the rivers and lakes come out 11.6 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. A utility here that draws from the aquifer can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 318 lb of salt a year (8 bags of 40 lb, about $57), 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 $157 a year.
Sizing at 14.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 870 | 24,000 | 106 lb |
| 2 | 1,740 | 24,000 | 212 lb |
| 4 | 3,480 | 32,000 | 423 lb |
| 6 | 5,220 | 40,000 | 635 lb |
Colusa County against the rest of California
Among the 58 California counties with data, Colusa County is number 12 of 58 counting from the hardest. Across the whole country it is harder than 68% of counties.
Softest in California: Sierra County at 1.7 gpg. Hardest: Calaveras County at 98.3 gpg. Closest to Colusa County: San Diego County (14.3), Sutter County (14.2), Yolo County (14.1).