Illinois utilities with moderately hard water.

61 to 120 mg/L (3.6 to 7 grains per gallon). 73 utilities serving 1.2 million people as they report it, largest first.

All 73, by people served

Illinois utilities with moderately hard water, 1 to 73
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Springfield	Springfield	117,444	90	5.3
IL American - West Suburban	Bolingbrook	73,978	87	5.1
Glenview	Glenview	47,856	83	4.9
O Fallon	O Fallon	46,603	120	7
Moline	Moline	44,500	110	6.4
Quincy	Quincy	42,000	120	7
South Stickny SD	Burbank (South Stickney)	30,000	78	4.6
Ej Water Cooperative	Dieterich	29,720	113	6.6
Montgomery	Montgomery	28,956	76	4.4
Edwardsville	Edwardsville	26,808	110	6.4
Morton Grove	Morton Grove	25,297	85	5
West Chicago	West Chicago	25,166	99	5.8
IL American - Homer Township	Godfrey	24,543	81	4.7
Zion	Zion	24,442	87	5.1
Lisle	Lisle	24,223	79	4.6
Westmont	Westmont	24,161	120	7
Rolling Meadows	Rolling Meadows	23,329	89	5.2
Yorkville	Yorkville	23,000	81	4.8
Bloomingdale	Weston	22,018	76	4.4
Blue Island	Blue Island	21,494	83	4.8
Grayslake	Grays Lake	21,248	82	4.8
Geneva	Geneva	21,247	64	3.7
Libertyville	Libertyville	20,500	79	4.6
Evergreen Park	Evergreen Park	19,943	78	4.6
Mattoon	Mattoon	19,500	99	5.8
Deerfield	Deerfield	19,196	89	5.2
Franklin Park	Franklin Park	18,467	85	5
Charleston	Charleston	17,286	86	5
Bridgeview	Bridgeview	16,467	91	5.3
Bethalto	Bethalto	15,210	74	4.3
Macomb	Macomb	15,051	95	5.6
Midlothian	Midlothian	14,819	79	4.6
Morris	Morris	14,775	62	3.6
Wood Dale	Wood Dale	14,012	77	4.5
Effingham	Effingham	12,252	78	4.5
IL American - Chicago Suburban	Godfrey	11,187	86	5
Highland	Highland	10,674	76	4.4
Waterloo	Waterloo	10,190	118	6.9
Olney	Olney	8,877	85	4.9
Western Illinois University	Macomb	8,000	80	4.7
Fosterburg PWD	Alton	7,940	112	6.5
Lincolnshire	Lincolnshire	7,940	87	5.1
Salem	Salem	7,905	78	4.6
Long Creek Township PWS	Long Creek	7,850	78	4.6
Mahomet	Mahomet	7,000	94	5.5
IL American - Valley View	Godfrey	6,721	86	5
Carlinville	Carlinville	6,598	100	5.8
Winthrop Harbor	Winthrop Harbor	6,565	108	6.3
Williamsville	Williamsville	6,198	64	3.7
Braidwood	Braidwood	6,194	103	6
Mount Zion	Mount Zion	5,833	105	6.1
Pana	Pana	5,800	100	5.8
Spring Valley	Spring Valley	5,582	85	5
Sangamon Valley PWD	Mahomet	5,300	76	4.5
Caterpillar Trail PWD	Eureka	5,125	84	4.9
Lebanon	Lebanon	4,714	106	6.2
Athens	Athens	4,575	119	7
Auburn	Auburn	4,574	65	3.8
Oglesby	Oglesby	4,500	105	6.1
Hillsboro	Hillsboro	4,402	97	5.7
Smithton	Smithton	4,381	80	4.7
New Baden	New Baden	4,178	75	4.4
Rochester	Rochester	3,856	64	3.7
Gillespie	Gillespie	3,737	120	7
Woodlawn	Woodlawn	3,587	61	3.5
Le Roy	Le Roy	3,498	110	6.4
Forsyth	Forsyth	3,490	79	4.6
Aledo	Aledo	3,470	108	6.3
Mackinaw	Mackinaw	3,399	61	3.5
Virden	Virden	3,274	107	6.3
Holiday Shores SD	Edwardsville	3,025	115	6.7
Kenilworth	Kenilworth	2,514	120	7
IL American - Country Club	Godfrey	1,014	82	4.8

Source: Illinois Environmental Protection Agency, Bureau of Water, 327 utilities, results from Aug. 2, 2016 to July 29, 2026, read Oct. 17, 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.

All 73, by people served

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