How hard is the water in Plymouth County, IA?
31.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Plymouth County, IA is 540 mg/L as calcium carbonate, which is 31.5 gpg. That is very hard on the USGS scale. It comes from 24 samples at 9 sites between 1990 and 2006, 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 26.3 and 35 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 31.5 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.
More on sizing a softener for your household.
From 23.4 to 52.6 gpg
The softest single sample on record in Plymouth County was 400 mg/L and the hardest 900 mg/L, a 2-fold gap. The top quarter of sites read above 35 gpg and the bottom quarter below 26.3 gpg.
Wells 31.5 gpg, rivers and lakes 24.1 gpg
24 groundwater samples from 9 wells put the median at 540 mg/L. 88 surface samples from 2 sites put it at 412.2 mg/L. In Plymouth County the wells come out 7.4 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 40,000-grain unit covers a week between regenerations. Expect about 689 lb of salt a year (18 bags of 40 lb, about $124), 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 $224 a year.
Sizing at 31.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,890 | 24,000 | 230 lb |
| 2 | 3,780 | 32,000 | 460 lb |
| 4 | 7,560 | 64,000 | 920 lb |
| 6 | 11,340 | 80,000 | 1,380 lb |
Plymouth County against the rest of Iowa
Among the 93 Iowa counties with data, Plymouth County is number 7 of 93 counting from the hardest. Across the whole country it is harder than 95% of counties.
Softest in Iowa: Taylor County at 8.2 gpg. Hardest: Pocahontas County at 45.3 gpg. Closest to Plymouth County: Emmet County (31.8), Lyon County (31.2), Sioux County (31).