Utilities / Wisconsin

Wisconsin water hardness

2 Wisconsin systems with a hardness figure read from an official page, each on the retrieval date printed against it below. This is not a list of every utility in Wisconsin; it is the list of those whose published figure has been verified here.

Soft Soft 0–60

Moderately hard Moderate 61–120

Hard Hard 121–180

Very hard Very hard 181+

Milwaukee, WI 137 mg/L 8.01 gpg Hard
Madison, WI 324.9 mg/L 19 gpg Very hard

mg/L as calcium carbonate. Each classification band is drawn the same width, so the axis is not linear in mg/L.

Wisconsin systems on the USGS classification. Each row links to that system's published figure, report year and conversion. Grains per gallon are the utility's own figure where it published one, and our conversion at 17.1 mg/L per grain where it did not.

Milwaukee, WI — Milwaukee Water Works 137 mg/L (8 gpg) Hard Published range 112–142 mg/L. Milwaukee Water Works, “Water hardness” customer FAQ. Retrieved 2026-10-17.
Madison, WI — Madison Water Utility 324.9 mg/L (19 gpg) Very hard Published range 307.8–342 mg/L. Madison Water Utility water quality frequently asked questions. Retrieved 2026-10-17.

If your Wisconsin system is not above

Only 2 Wisconsin systems have been transcribed here, so most Wisconsin readers will not find theirs. Find the water system that serves you walks through the free EPA search that names your system and the EPA lookup that finds its annual report, which is the document that carries a hardness figure for your water. There is no ZIP-code hardness figure on this site, and that page explains why a ZIP code cannot carry one honestly: a ZIP code is a postal boundary and a water system is a pipe network, and they do not line up.

Other states with verified systems

All verified systems Convert a figure from your own report How to read a water quality report