California utilities whose water varies in hardness.

Water in more than one band, depending on where or when it was sampled: each is given as its range, softest to hardest. 759 utilities serving 28 million people as they report it, largest first.

301 to 400 of 759, by people served

California utilities whose water varies in hardness, 301 to 400, 301 to 400
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Maywood Mutual Water Co. #3	Maywood	6,059	157 to 277	9.2 to 16.2
Bellflower Municipal Water System	Rosemead	6,032	166 to 233	9.7 to 13.6
Lemoore Naval Air Station	Lemoore	6,000	92 to 160	5.4 to 9.4
Golden State Water Company - Los Osos	Santa Maria	5,942	88 to 335	5.1 to 19.6
Cal Am - Meadowbrook	Sacramento	5,723	81 to 278	4.7 to 16.3
Golden State Water Co - Arden Water Serv	Rancho Cordova	5,679	110 to 240	6.4 to 14
Keyes Community Services Dist.	Keyes	5,672	53 to 112	3.1 to 6.5
Bear Valley CSD	Tehachapi	5,592	140 to 350	8.2 to 20.5
Palm Ranch Irrigation Dist.	Quartz Hill	5,507	150 to 270	8.8 to 15.8
Hilmar County Water District	Hilmar	5,504	77 to 123	4.5 to 7.2
Millview County Water District	Ukiah	5,500	88 to 143	5.1 to 8.4
City of St. Helena	St. Helena	5,386	23 to 116	1.3 to 6.8
Yosemite Spring Park Util Co	Coarsegold	5,300	71 to 270	4.2 to 15.8
Running Springs Water District	Running Springs	5,268	54 to 200	3.2 to 11.7
Wasco St. Prison Reception Ctr	Wasco	5,217	74 to 185	4.3 to 10.8
Stallion Springs CSD	Tehachapi	4,910	9.5 to 263	0.6 to 15.4
Sswd - del Paso Manor Service Area	Sacramento	4,854	83 to 150	4.8 to 8.8
City of Lakeport	Lakeport	4,762	96 to 183	5.6 to 10.7
Coachella Vwd: I.D. No. 8	Palm Desert	4,700	81 to 258	4.7 to 15.1
Golden State Water Co. - Clearlake System	Rancho Cordova	4,623	150 to 225	8.8 to 13.1
Ivanhoe Public Utility Dist	Ivanhoe	4,580	110 to 330	6.4 to 19.3
Golden State Water Company - Nipomo	Rancho Cordova	4,512	57 to 320	3.3 to 18.7
Slvwd - Felton Water System	Boulder Creek	4,491	105 to 270	6.1 to 15.8
Chuckawalla Valley State Prison	Blythe	4,331	29 to 97	1.7 to 5.7
Cal Am - Arden	Sacramento	4,178	64 to 195	3.7 to 11.4
Planada CSD	Planada	4,164	110 to 209	6.4 to 12.2
City of Wheatland	Wheatland	4,124	98 to 296	5.7 to 17.3
Kelseyville Co Waterworks District 3	Lakeport	4,102	112 to 163	6.5 to 9.5
City of San Joaquin	San Joaquin	4,060	30 to 96	1.8 to 5.6
Sheep Creek Water Company	Phelan	4,002	140 to 610	8.2 to 35.7
Weaverville C.S.D.	Weaverville	3,975	37 to 65	2.2 to 3.8
Bighorn - Desert View Water Agency	Yucca Valley	3,916	61 to 170	3.6 to 9.9
Woodlands Development	Arroyo Grande	3,862	54 to 575	3.2 to 33.6
Cdcr - High Desert State Prison	Susanville	3,857	22 to 170	1.3 to 9.9
City of Bishop	Bishop	3,819	35 to 77	2 to 4.5
San Joaquin County - Mokelumne Acres	Stockton	3,802	71 to 313	4.2 to 18.3
Willow County Water District	Ukiah	3,797	114 to 125	6.7 to 7.3
American Valley CSD	Quincy	3,778	29 to 100	1.7 to 5.8
Idyllwild Water District	Idyllwild	3,762	25 to 88	1.5 to 5.1
Cal Am - Oakhurst	Sacramento	3,710	61 to 845	3.6 to 49.4
Esparto C.S.D.	Esparto	3,572	129 to 363	7.5 to 21.2
Cobb Area County Water District	Cobb	3,515	25 to 93	1.5 to 5.4
North Gualala Water Company	Gualala	3,508	82 to 121	4.8 to 7
San Antonio Water Company	Upland	3,441	160 to 300	9.4 to 17.5
Borrego WD	Borrego Springs	3,429	36 to 230	2.1 to 13.5
Rio Alto Water District	Cottonwood	3,377	56 to 89	3.3 to 5.2
Cottonwood Water District	Cottonwood	3,316	38 to 69	2.2 to 4
Lukins Brothers Water Company	South Lake Tahoe	3,277	46 to 86	2.7 to 5
Cwsc Oak Hills	San Jose	3,214	160 to 300	9.4 to 17.5
Northstar C.S.D.	Truckee	3,165	47 to 93	2.7 to 5.5
Madera Co Md10a - Madera Ranchos	Madera	3,072	96 to 230	5.6 to 13.5
Cal Am - Bass Lake	Sacramento	3,066	7.3 to 166	0.4 to 9.7
Littlerock Creek Irrigation Dist.	Littlerock	3,066	115 to 160	6.7 to 9.4
Madera Co CSA 22c Gunner Ranch	Madera	3,050	59 to 71	3.4 to 4.2
Green Valley MWC	Green Valley Lake	2,993	21 to 170	1.2 to 9.9
Aromas Water District	Aromas	2,988	144 to 391	8.4 to 22.9
Heritage Ranch CSD	Paso Robles	2,956	113 to 147	6.6 to 8.6
NPS - Ash Mountain	Three Rivers	2,930	164 to 188	9.6 to 11
Sutter Community S.D.	Sutter	2,904	170 to 282	9.9 to 16.5
Palo Alto Park Mutual Water Company	East Palo Alto	2,900	90 to 342	5.3 to 20
Fcwwd 41/shaver Lake	Fresno	2,859	9.7 to 145	0.6 to 8.5
City of Vallejo - Lakes System	Vallejo	2,800	23 to 172	1.3 to 10.1
Rio Cosumnes Correctional Center [sws]	Sacramento	2,800	27 to 280	1.6 to 16.4
Lake Shastina C.S.D	Weed	2,790	120 to 144	7 to 8.4
Fort Hunter Liggett	Fort Hunter Liggett	2,753	122 to 226	7.1 to 13.2
City of Alturas	Alturas	2,715	87 to 183	5.1 to 10.7
Strathmore Public Util Dist	Strathmore	2,669	8.7 to 170	0.5 to 9.9
Terra Bella Irrigation District - Tbt	Terra Bella	2,656	7.5 to 190	0.4 to 11.1
Arrowhead Villas Mutual Service Company	Skyforest	2,644	120 to 140	7 to 8.2
Fulton Water Company	Carnelian Bay	2,593	33 to 77	1.9 to 4.5
Pine Valley Mutual WC	Pine Valley	2,574	155 to 398	9.1 to 23.3
Rogina Water Company Inc.	Talmage	2,554	101 to 168	5.9 to 9.8
Alpine Water Users Association	Twin Peaks	2,534	49 to 150	2.9 to 8.8
Erskine Creek WC	Shafter	2,500	160 to 190	9.4 to 11.1
Valley of Enchantment MWC	Crestline	2,471	64 to 140	3.7 to 8.2
Cedarpines Park MWC	Cedarpines Park	2,458	49 to 135	2.9 to 7.9
Awa - Camanche Village	Sutter Creek	2,402	49 to 110	2.8 to 6.4
Twain Harte Community Services District	Twain Harte	2,378	8.7 to 100	0.5 to 5.8
Cws - Kernville	San Jose	2,376	38 to 223	2.2 to 13.1
Kirkwood Meadows Public Utility District	Kirkwood	2,297	27 to 67	1.6 to 3.9
Mountain Gate C.S.D.	Redding	2,227	50 to 218	2.9 to 12.7
Santa Nella County Water District	Santa Nella	2,211	103 to 250	6 to 14.6
Poplar Comm Service Dist	Poplar	2,200	170 to 200	9.9 to 11.7
Golden State Water Co - Apple Vly North	Apple Valley	2,097	130 to 190	7.6 to 11.1
City of Biggs	Biggs	2,060	127 to 224	7.4 to 13.1
Golden State Water Company - Cypress Ridge	Rancho Cordova	2,032	39 to 260	2.3 to 15.2
Fcsa 47 - Quail Lake Estates	Fresno	2,010	103 to 135	6 to 7.9
Beale Air Force Base	Beale AFB	2,000	89 to 127	5.2 to 7.4
Mariposa Public Utility Dist	Mariposa	2,000	7.9 to 260	0.5 to 15.2
Bolinas Community PUD	Bolinas	1,937	31 to 381	1.8 to 22.3
Lost Hills Utility District	Lost Hills	1,926	85 to 130	5 to 7.6
Cabazon Water District	Cabazon	1,900	170 to 195	9.9 to 11.4
North Marin WD - Pt. Reyes	Novato	1,841	100 to 365	5.8 to 21.3
Searles Valley Minerals Operations Inc	Trona	1,818	6.3 to 355	0.4 to 20.8
Kinneloa Irrigation Dist.	Pasadena	1,808	102 to 296	6 to 17.3
London Community Serv Dist	Dinuba	1,800	94 to 130	5.5 to 7.6
Lake Elizabeth Mutual Water Co.	Elizabeth Lake	1,790	79 to 233	4.6 to 13.6
Madera Co Sa3 - Parksdale	Madera	1,789	58 to 92	3.4 to 5.4
Cold Springs Water Co	Cold Springs	1,771	46 to 98	2.7 to 5.7
Majestic Pines Community SD	Julian	1,768	97 to 150	5.7 to 8.8

Source: California State Water Resources Control Board, Division of Drinking Water, 2,449 utilities, results from Jan. 2, 2019 to July 14, 2026, read Oct. 10, 2026. Each sampling point is taken at its median; a figure is typical where every point falls in one band.

Also: 7 utilities’ own water quality reports, read by hand, each named on the utility’s page.

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.

301 to 400 of 759, by people served

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