How hard is the water in Imperial County, CA?
9.5 grains per gallon
A softener is worth it here.
The median hardness measured in Imperial County, CA is 162 mg/L as calcium carbonate, which is 9.5 gpg. That is hard on the USGS scale. It comes from 623 samples at 77 sites between 1990 and 2023, 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 4.2 and 19.3 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 9.5 gpg a softener is worth getting, mainly to protect the water heater and cut soap use. Get at least two quotes, ask each installer what grain capacity they are fitting, and check it against the sizing table below. Because Imperial 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 0.6 to 136.1 gpg
The softest single sample on record in Imperial County was 11.1 mg/L and the hardest 2,330 mg/L, a 210-fold gap. The top quarter of sites read above 19.3 gpg and the bottom quarter below 4.2 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 9.5 gpg, rivers and lakes 22.2 gpg
623 groundwater samples from 77 wells put the median at 162 mg/L. 263 surface samples from 18 sites put it at 380.8 mg/L. In Imperial County the rivers and lakes come out 12.7 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 207 lb of salt a year (6 bags of 40 lb, about $37), 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 $137 a year.
Sizing at 9.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 570 | 24,000 | 69 lb |
| 2 | 1,140 | 24,000 | 139 lb |
| 4 | 2,280 | 24,000 | 277 lb |
| 6 | 3,420 | 24,000 | 416 lb |
Imperial County against the rest of California
Among the 58 California counties with data, Imperial County is number 27 of 58 counting from the hardest. Across the whole country it is harder than 49% of counties.
Softest in California: Sierra County at 1.7 gpg. Hardest: Calaveras County at 98.3 gpg. Closest to Imperial County: San Joaquin County (9.5), Humboldt County (9.3), Mendocino County (9.2).