How hard is the water in Linn County, IA?
15.8 grains per gallon
A softener will pay its way here.
The median hardness measured in Linn County, IA is 270 mg/L as calcium carbonate, which is 15.8 gpg. That is very hard on the USGS scale. It comes from 1,023 samples at 144 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 14.7 and 18 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 15.8 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 2.2 to 32.8 gpg
The softest single sample on record in Linn County was 38 mg/L and the hardest 561.5 mg/L, a 15-fold gap. The top quarter of sites read above 18 gpg and the bottom quarter below 14.7 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 15.8 gpg, rivers and lakes 14.5 gpg
1,023 groundwater samples from 144 wells put the median at 270 mg/L. 163 surface samples from 4 sites put it at 248.8 mg/L. In Linn County the wells come out 1.3 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. The two sources are close, so the county figure should hold whichever one your tap is on.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 344 lb of salt a year (9 bags of 40 lb, about $62), 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 $162 a year.
Sizing at 15.8 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 948 | 24,000 | 115 lb |
| 2 | 1,896 | 24,000 | 231 lb |
| 4 | 3,792 | 32,000 | 461 lb |
| 6 | 5,688 | 40,000 | 692 lb |
Linn County against the rest of Iowa
Among the 93 Iowa counties with data, Linn County is number 74 of 93 counting from the hardest. Across the whole country it is harder than 72% of counties.
Softest in Iowa: Taylor County at 8.2 gpg. Hardest: Pocahontas County at 45.3 gpg. Closest to Linn County: Adams County (15.8), Delaware County (15.8), Van Buren County (15.5).