Wisconsin water hardness, by utility.

940 Wisconsin utilities serving 3.7 million people as they report it, from the state’s own results. Hardness is the calcium and magnesium in water; EPA sets no limit for it.

The short answer

Very hard water reaches the most people here: 580 utilities serving 1.6 million. Another 124 utilities, serving 559,647, have water in more than one band.

The largest, Milwaukee Waterworks, is hard, typically 140 mg/L (8.2 grains per gallon).

Very hard

Above 180 mg/L (10.5 grains per gallon). 580 utilities serving 1.6 million people; the 25 largest are here.

Wisconsin utilities: very hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Madison Water Utility	Madison	272,000	345	20.2
Waukesha Water Utility	Waukesha	70,718	320	18.7
Janesville Water Utility	Janesville	64,415	363	21.2
Fond Du Lac Waterworks	Fond Du Lac	44,678	375	21.9
Sun Prairie Utilities	Sun Prairie	39,300	330	19.3
City of Beloit	Beloit	36,677	337	19.7
West Bend Waterworks	West Bend	32,149	408	23.8
Fitchburg Utility Dist 1	Fitchburg	29,900	270	15.8
Brookfield Water Utility	Brookfield	29,070	390	22.8
Watertown Waterworks	Watertown	23,945	355	20.8
Middleton Waterworks	Middleton	23,868	325	19
Germantown Water Utility	Germantown	20,027	420	24.6
Marshfield Utilities	Marshfield	18,815	268	15.6
Onalaska Waterworks	Onalaska	18,000	344	20.1
Kaukauna Utilities	Kaukauna	17,493	655	38.3
Hartford Waterworks	Hartford	15,805	425	24.9
Oconomowoc Waterworks	Oconomowoc	15,805	320	18.7
Waunakee Waterworks	Waunakee	14,879	280	16.4
Verona Waterworks	Verona	14,030	362	21.2
Whitewater Waterworks	Whitewater	14,000	320	18.7
Plover Waterworks	Plover	13,486	250	14.6
Stoughton Waterworks	Stoughton	13,078	325	19
Cedarburg L & W Commission	Cedarburg	12,500	388	22.7
Fort Atkinson Waterworks	Fort Atkinson	12,390	278	16.2
Grafton Waterworks	Grafton	12,269	360	21.1

All 580 with very hard water

Hard

121 to 180 mg/L (7.1 to 10.5 grains per gallon). 79 utilities serving 1.2 million people; the 25 largest are here.

Wisconsin utilities: hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Milwaukee Waterworks	Milwaukee	626,000	140	8.2
Green Bay Waterworks	Green Bay	107,369	140	8.2
Racine Waterworks	Racine	105,100	130	7.6
Kenosha Water Utility	Kenosha	99,218	133	7.7
West Allis Waterworks	West Allis	63,240	135	7.9
Oshkosh Waterworks	Oshkosh	63,000	170	9.9
Howard Waterworks	Green Bay	21,133	159	9.3
Cudahy Waterworks	Cudahy	18,659	140	8.2
Beaver Dam Water Utility	Beaver Dam	16,200	130	7.6
Menasha Elec & Water Util	Menasha	15,144	171	10
Two Rivers Waterworks	Two Rivers	11,270	138	8
Kronenwetter Water & Sewer Utility	Kronenwetter	6,931	140	8.2
Oconto Waterworks	Oconto	4,583	170	9.9
Chilton Waterworks	Chilton	4,191	165	9.6
Wrightstown Waterworks	Wrightstown	3,815	136	8
Rothschild Waterworks	Rothschild	3,190	150	8.8
Osceola Waterworks	Osceola	2,680	155	9.1
Westby Waterworks	Westby	2,400	159	9.3
Marathon City Waterworks	Marathon City	1,695	170	9.9
Grantsburg Waterworks	Grantsburg	1,460	153	8.9
Elroy Waterworks	Elroy	1,333	143	8.3
Hillsboro Waterworks	Hillsboro	1,325	153	8.9
Greenwood Waterworks	Greenwood	1,079	138	8.1
Turtle Lake Waterworks	Turtle Lake	1,073	160	9.4
Balsam Lake Waterworks	Balsam Lake	1,031	130	7.6

All 79 with hard water

Moderately hard

61 to 120 mg/L (3.6 to 7 grains per gallon). 81 utilities serving 308,460 people; the 25 largest are here.

Wisconsin utilities: moderately hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Appleton Waterworks	Menasha	74,511	79	4.6
Eau Claire Waterworks	Eau Claire	70,587	107	6.3
Wausau Waterworks	Wausau	39,994	75	4.4
Chippewa Falls Waterworks	Chippewa Falls	13,375	82	4.8
Darboy Sanitary Dist 1	Appleton	13,024	108	6.3
Fox Crossing Utilities East	Neenah	10,927	87	5.1
Fort McCoy North Post	Fort McCoy	10,000	96	5.6
Waupun Utilities	Waupun	8,056	81	4.7
Antigo Waterworks	Antigo	7,780	115	6.7
Kimberly Waterworks	Kimberly	7,608	93	5.4
Union Grove Waterworks	Union Grove	4,900	97	5.7
Mosinee Waterworks	Mosinee	3,406	90	5.3
Algoma Waterworks	Algoma	3,219	115	6.7
Tomahawk Waterworks	Tomahawk	3,180	89	5.2
Mondovi Waterworks	Mondovi	2,667	76	4.4
Spooner Waterworks	Spooner	2,653	101	5.9
Williams Bay Waterworks	Williams Bay	2,601	96	5.6
Winneconne Waterworks	Winneconne	2,502	93	5.5
Nekoosa Waterworks	Nekoosa	2,394	64	3.8
Neillsville Waterworks	Neillsville	2,384	90	5.2
Washburn Waterworks	Washburn	2,280	88	5.1
Whitehall Waterworks	Whitehall	1,820	110	6.4
Cameron Waterworks	Cameron	1,787	71	4.2
Phillips Waterworks	Phillips	1,473	104	6.1
Mosinee East System	Mosinee	1,046	100	5.8

All 81 with moderately hard water

Soft

Up to 60 mg/L (3.5 grains per gallon). 76 utilities serving 31,231 people; the 25 largest are here.

Wisconsin utilities: soft water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Ashland Water Utility	Ashland	8,000	53	3.1
Bloomer Waterworks	Bloomer	3,680	53	3.1
Brockway Sanitary Dist 1	Black River Falls	2,692	33	1.9
Cornell Waterworks	Cornell	1,390	58	3.4
Colfax Waterworks	Colfax	1,102	21	1.2
Strum Waterworks	Strum	1,100	54	3.2
Hustisford Waterworks	Hustisford	1,063	7.3	0.4
Biron Water Utility	Wisconsin Rapids	879	31	1.8
Camp Douglas Waterworks	Camp Douglas	640	34	2
Eleva Waterworks	Eleva	635	51	3
Delafield Square	Delafield	587	2.4	0.1
Warrens Waterworks	Warrens	540	9.8	0.6
Merrillan Waterworks	Merrillan	531	28	1.6
Alma Center Waterworks	Alma Center	487	36	2.1
Lyndon Station Waterworks	Lyndon Station	474	31	1.8
Fairchild Waterworks	Fairchild	451	32	1.8
North Hills MHP	Beaver Dam	420	1.5	0.1
Villa Diann MHP	Eau Claire	420	53	3.1
Pigeon Falls Waterworks	Pigeon Falls	409	35	2
WI Air National Guard Volk Field	Camp Douglas	400	20	1.2
Delavan Club Condos	Delavan	395	1.1	0.1
Northernaire Sanitary District	Three Lakes	315	10	0.6
Evergreen Villa Mobile Homes	Hull	250	41	2.4
Fort McCoy South Post	Fort McCoy	250	15	0.9
Genesee Lake School South	Oconomowoc	230	1.4	0.1

All 76 with soft water

Varies

Water in more than one band, depending on where or when it was sampled: each is given as its range, softest to hardest, and its report says more. 124 utilities serving 559,647 people; the 25 largest are here.

Wisconsin utilities: varies water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
La Crosse Waterworks	La Crosse	53,000	64 to 390	3.7 to 22.8
Manitowoc Waterworks	Manitowoc	34,500	130 to 470	7.6 to 27.5
Stevens Point Waterworks	Stevens Point	26,717	140 to 205	8.2 to 12
South Milwaukee Waterworks	South Milwaukee	21,340	120 to 125	7 to 7.3
Wis Rapids Water Works & Lighting Comm	Wisconsin Rapids	20,000	60 to 63	3.5 to 3.7
Hudson Waterworks	Hudson	18,558	165 to 280	9.6 to 16.4
River Falls Waterworks	River Falls	16,000	175 to 205	10.2 to 12
Weston Municipal Utilities	Weston	16,000	97 to 210	5.7 to 12.3
Menomonie Waterworks	Menomonie	15,950	110 to 180	6.4 to 10.5
Fox Crossing Utilities West	Neenah	14,000	44 to 64	2.6 to 3.7
Baraboo Waterworks	Baraboo	12,703	148 to 329	8.7 to 19.2
Little Chute Waterworks	Little Chute	12,168	53 to 205	3.1 to 12
Burlington Waterworks	Burlington	11,043	110 to 245	6.4 to 14.3
New Richmond Waterworks	New Richmond	10,824	175 to 215	10.2 to 12.6
Portage Waterworks	Portage	10,437	109 to 144	6.3 to 8.4
Elkhorn Waterworks	Elkhorn	10,317	47 to 140	2.7 to 8.2
Sparta Waterworks	Sparta	10,025	46 to 186	2.7 to 10.8
Reedsburg Waterworks	Reedsburg	9,984	114 to 224	6.6 to 13.1
Merrill Waterworks	Merrill	9,661	97 to 145	5.7 to 8.5
Altoona Waterworks	Altoona	9,627	71 to 140	4.2 to 8.2
Tomah Waterworks	Tomah	9,192	39 to 132	2.3 to 7.7
Rice Lake Waterworks	Rice Lake	9,012	82 to 135	4.8 to 7.9
Rhinelander Water & Wastewater	Rhinelander	8,234	53 to 110	3.1 to 6.4
Muskego Water Utility	Muskego	8,150	51 to 400	3 to 23.4
New London Waterworks	New London	7,187	130 to 460	7.6 to 26.9

All 124 whose water varies

Source: Wisconsin Department of Natural Resources, Drinking Water Program, 940 utilities, results from Feb. 4, 2015 to Sept. 24, 2026, read Oct. 10, 2026. Each sampling point is taken at its median; a figure is typical where every point falls in one band.

Bands are the U.S. Geological Survey’s, at 17.1 mg/L to the grain. People served is what each utility reports; where one sells water to another, the same people can be counted twice. How hardness is measured here.

Very hard

Hard

Moderately hard

Soft

Varies

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