How hard is the water in Black Hawk County, IA?
17.1 grains per gallon
A softener will pay its way here.
The median hardness measured in Black Hawk County, IA is 293 mg/L as calcium carbonate, which is 17.1 gpg. That is very hard on the USGS scale. It comes from 41 samples at 23 sites between 1990 and 2017, 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 14.2 and 21.4 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 17.1 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 10.7 to 26.6 gpg
The softest single sample on record in Black Hawk County was 184 mg/L and the hardest 456 mg/L, a 2-fold gap. The top quarter of sites read above 21.4 gpg and the bottom quarter below 14.2 gpg.
Wells 17.1 gpg, rivers and lakes 15.4 gpg
41 groundwater samples from 23 wells put the median at 293 mg/L. 58 surface samples from 5 sites put it at 263 mg/L. In Black Hawk County the wells come out 1.7 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. 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 374 lb of salt a year (10 bags of 40 lb, about $67), 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 $167 a year.
Sizing at 17.1 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,026 | 24,000 | 125 lb |
| 2 | 2,052 | 24,000 | 250 lb |
| 4 | 4,104 | 32,000 | 499 lb |
| 6 | 6,156 | 48,000 | 749 lb |
Black Hawk County against the rest of Iowa
Among the 93 Iowa counties with data, Black Hawk County is number 65 of 93 counting from the hardest. Across the whole country it is harder than 76% of counties.
Softest in Iowa: Taylor County at 8.2 gpg. Hardest: Pocahontas County at 45.3 gpg. Closest to Black Hawk County: Howard County (17.2), Iowa County (16.9), Marion County (16.9).