Illinois utilities with very hard water.

Above 180 mg/L (10.5 grains per gallon). 113 utilities serving 1.5 million people as they report it, largest first.

All 113, by people served

Illinois utilities with very hard water, 1 to 113
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Joliet	Joliet	160,000	224	13.1
Rockford	Rockford	147,051	313	18.3
IL American - Peoria	Peoria	137,575	267	15.6
Rock Island	Rock Island	39,018	215	12.6
Oswego	Oswego	38,169	235	13.7
North Park PWD	Machesney Park	35,580	395	23.1
IL American - Pekin	Pekin	31,731	289	16.9
Galesburg	Galesburg	31,620	280	16.4
Algonquin	Algonquin	30,700	385	22.5
Collinsville	Collinsville	30,616	230	13.4
Batavia	Batavia	26,098	304	17.8
Belvidere	Belvidere	25,339	380	22.2
Frankfort	Frankfort	24,000	561	32.8
Freeport	Freeport	23,930	415	24.3
Loves Park	Loves Park	23,335	270	15.8
Lockport	Lockport	23,100	541	31.6
East Peoria	East Peoria	22,484	415	24.3
McHenry	McHenry	22,335	470	27.5
Sycamore	Sycamore	18,500	289	16.9
North Aurora	North Aurora	18,261	235	13.7
Troy	Troy	16,962	560	32.8
Canton	Canton	16,748	328	19.2
Dixon	Dixon	15,096	305	17.8
Antioch	Antioch	14,175	270	15.8
Channahon	Channahon	13,380	273	16
Plano	Plano	12,600	440	25.7
Warrenville	Warrenville	12,350	481	28.1
Fox Lake	Fox Lake	11,780	495	28.9
Robinson - Palestine Water Commission	Robinson	11,331	250	14.6
Wood River	Wood River	10,464	240	14
Manhattan	Manhattan	10,340	292	17
Barrington	Barrington	10,327	500	29.2
Sauk Village	Sauk	9,921	636	37.2
La Salle	La Salle	9,700	465	27.2
Steger	Steger	9,700	555	32.5
Clark - Edgar RWD	Marshall	9,657	335	19.6
Harvard	Harvard	9,469	300	17.5
Rochelle	Rochelle	9,446	280	16.4
Paris	Paris	9,100	270	15.8
Rock Falls	Rock Falls	8,620	350	20.5
Crete	Crete	8,386	510	29.8
IL American - Whispering Hills	Godfrey	8,300	380	22.2
Rockton	Rockton	7,863	315	18.4
Rock Island Arsenal, US Army	Rock Island	7,800	237	13.9
North Tazewell PWD	East Peoria	7,625	360	21.1
Marengo	Marengo	7,572	370	21.6
Sandwich	Sandwich	7,156	485	28.4
Mount Carmel	Mount Carmel	7,015	272	15.9
Chillicothe	Chillicothe	6,660	300	17.5
Elburn	Elburn	6,559	250	14.6
Geneseo	Geneseo	6,539	415	24.3
Aqua Illinois - Candlewick Dvn	Glenview	6,426	340	19.9
Dallas Rural Water District	Dallas City	6,370	365	21.3
Metropolis	Metropolis	6,309	210	12.3
Beardstown	Beardstown	5,951	370	21.6
Peoria Heights	Peoria Heights	5,908	460	26.9
Hoopeston	Hoopeston	5,802	340	19.9
Mill Creek PWD	Quincy	5,755	360	21.1
Grandwood Park Subdivision - Lake Co Pw	Libertyville	5,751	250	14.6
Fayette Water Company	Brownstown	5,608	266	15.6
Shelbyville	Shelbyville	5,600	375	21.9
Pike County PWD 1	Pittsfield	5,375	245	14.3
Genoa	Genoa	5,298	330	19.3
Mitchell PWD	Granite City	5,253	232	13.6
Monee	Monee	5,148	550	32.2
Aqua Illinois - Willowbrook	Manhattan	5,100	365	21.3
Marseilles	Marseilles	5,061	306	17.9
Milan	Milan	4,945	375	21.9
Creve Coeur	Creve Coeur	4,934	540	31.6
Breese	Breese	4,772	190	11.1
IL American - Lake Holiday	Godfrey	4,750	300	17.5
Cherry Valley	Cherry Valley	4,731	325	19
Beecher	Beecher	4,713	410	24
Fox River Grove	Fox River Grove	4,702	515	30.1
Lawrenceville	Lawrenceville	4,524	254	14.8
Calhoun County RWD	Hardin	4,438	480	28.1
Dwight	Dwight	4,400	290	17
Fountain Water District	Valmeyer	4,350	195	11.4
Riverton	Riverton	4,279	245	14.3
Georgetown	Georgetown	4,200	350	20.5
Paxton	Paxton	4,200	360	21.1
Morrison	Morrison	4,188	283	16.5
Aqua Illinois - Peotone	Peotone	4,182	550	32.2
Woodhaven	Sublette	4,100	240	14
Marshall	Marshall	3,947	295	17.3
Wonder Lake	Wonder Lake	3,870	330	19.3
Red Bud	Red Bud	3,804	360	21.1
Byron	Byron	3,784	341	19.9
Pleasant Valley PWD	Peoria	3,783	420	24.6
Lcpw - Pekara Subdivision	Libertyville	3,711	380	22.2
Three County PWD	New Douglas	3,575	199	11.6
South Jacksonville	South Jacksonville	3,501	380	22.2
Gibson City	Gibson City	3,500	383	22.4
Oregon	Oregon	3,449	305	17.8
Hardinville Water Company	Robinson	3,403	294	17.2
Rushville	Rushville	3,375	430	25.1
Fulton	Fulton	3,346	307	18
Galena	Galena	3,308	255	14.9
Havana	Havana	2,963	250	14.6
Carrollton	Carrollton	2,513	360	21.1
IL American - Galena	Godfrey	2,294	355	20.8
Crystal Lawns Addition Improvement Assoc	Joliet	1,435	478	27.9
IL American - Andalusia	Andalusia	1,184	237	13.8
Mendon	Mendon	953	372	21.8
Shady Oaks MHP	Chicago	912	250	14.6
Hanover	Hanover	863	273	15.9
Ashkum	Ashkum	800	369	21.5
Poplar Grove West - Countryside	Poplar Grove	790	420	24.6
Bluffs	Bluffs	748	485	28.4
IL American - Clarendon	Godfrey	625	690	40.4
Lake Windermere Estates Subdivision	Tremont	300	460	26.9
Dover	Dover	200	390	22.8
Low Point Water District	Lowpoint	200	240	14

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 113, by people served

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