How hard is the water in Door County, WI?

16.4 grains per gallon

A softener will pay its way here.

The median hardness measured in Door County, WI is 281 mg/L as calcium carbonate, which is 16.4 gpg. That is very hard on the USGS scale. It comes from 38 samples at 9 sites between 1990 and 2008, drawn from every sampling site in the county, wells and surface water together.

How much it varies here

Half the sites came in between 10.5 and 19.9 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 16.4 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 5.1 to 24.0 gpg

The softest single sample on record in Door County was 86.5 mg/L and the hardest 410 mg/L, a 5-fold gap. The top quarter of sites read above 19.9 gpg and the bottom quarter below 10.5 gpg.

What a softener would cost to run

For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 359 lb of salt a year (9 bags of 40 lb, about $65), 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 $165 a year.

Sizing at 16.4 gpg

Door County against the rest of Wisconsin

Among the 72 Wisconsin counties with data, Door County is number 23 of 72 counting from the hardest. Across the whole country it is harder than 74% of counties.

Softest in Wisconsin: Vilas County at 1.4 gpg. Hardest: Calumet County at 28.4 gpg. Closest to Door County: Portage County (16.4), Pierce County (16.6), Waupaca County (16.6).