How hard is the water in St. Croix County, WI?
14.2 grains per gallon
A softener will pay its way here.
The median hardness measured in St. Croix County, WI is 244 mg/L as calcium carbonate, which is 14.2 gpg. That is very hard on the USGS scale. It comes from 16 samples at 6 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 11.4 and 16.5 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: medium (how it is measured).
What to do next
At 14.2 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 10.2 to 16.8 gpg
The softest single sample on record in St. Croix County was 174 mg/L and the hardest 287 mg/L, a 2-fold gap. The top quarter of sites read above 16.5 gpg and the bottom quarter below 11.4 gpg.
Wells 14.2 gpg, rivers and lakes 10.5 gpg
16 groundwater samples from 6 wells put the median at 243.5 mg/L. 285 surface samples from 34 sites put it at 180 mg/L. In St. Croix County the wells come out 3.7 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 24,000-grain unit covers a week between regenerations. Expect about 311 lb of salt a year (8 bags of 40 lb, about $56), 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 $156 a year.
Sizing at 14.2 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 852 | 24,000 | 104 lb |
| 2 | 1,704 | 24,000 | 207 lb |
| 4 | 3,408 | 24,000 | 415 lb |
| 6 | 5,112 | 40,000 | 622 lb |
St. Croix County against the rest of Wisconsin
Among the 72 Wisconsin counties with data, St. Croix County is number 32 of 72 counting from the hardest. Across the whole country it is harder than 67% of counties.
Softest in Wisconsin: Vilas County at 1.4 gpg. Hardest: Calumet County at 28.4 gpg. Closest to St. Croix County: Milwaukee County (14), Brown County (14.8), Richland County (14.9).