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.

401 to 500 of 759, by people served

California utilities whose water varies in hardness, 401 to 500, 401 to 500
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Woodville Public Utility Dist	Tulare	1,740	155 to 190	9.1 to 11.1
Lake Don Pedro CSD	La Grange	1,700	21 to 233	1.2 to 13.6
Del Oro Water Co - Ferndale	Chico	1,662	130 to 296	7.6 to 17.3
Richgrove Community Services District	Richgrove	1,617	45 to 67	2.6 to 3.9
Cal - Water Service Co. - Hamilton City	Hamilton City	1,575	180 to 190	10.5 to 11.1
Oid - Oakdale Rural Water System #1	Oakdale	1,570	57 to 173	3.3 to 10.1
Pine Cove Water District	Idyllwild	1,540	24 to 69	1.4 to 4
Mariana Ranchos CWD	Apple Valley	1,502	61 to 140	3.6 to 8.2
California State University Fresno	Fresno	1,500	85 to 170	5 to 9.9
Sonoma State University	Rohnert Park	1,500	180 to 222	10.5 to 13
West Almanor M.W.C.	Chester	1,464	93 to 179	5.4 to 10.5
Los Molinos Comm. Services Dist.	Los Molinos	1,450	6.6 to 80	0.4 to 4.7
Inverness Public Utility Dist	Inverness	1,445	22 to 74	1.3 to 4.3
Biola Community Services Dist	Biola	1,427	59 to 70	3.5 to 4.1
Cal Am Water Company - Ambler Park	Pacific Grove	1,370	175 to 356	10.2 to 20.8
City of Modesto - del Rio	Modesto	1,346	54 to 122	3.2 to 7.1
Buttonwillow CWD	Buttonwillow	1,337	25 to 275	1.5 to 16.1
Lower Lake County Water District	Lower Lake	1,326	141 to 476	8.2 to 27.8
Rural North Vacaville Water District	Vacaville	1,313	67 to 125	3.9 to 7.3
Mission Springs Conference Center	Scotts Valley	1,310	168 to 277	9.8 to 16.2
Jackson Valley Irrigation District	Ione	1,303	15 to 77	0.8 to 4.5
Slo Cwwd No. 23 - Santa Margarita	San Luis Obispo	1,291	151 to 282	8.8 to 16.5
Del Oro River Island Serv Terr #1	Chico	1,277	78 to 390	4.5 to 22.8
Stratford PUD	Hanford	1,277	26 to 660	1.5 to 38.6
Green Valley CWD	Green Valley	1,275	150 to 304	8.8 to 17.8
Dwp - Fawnskin	Big Bear Lake	1,271	135 to 235	7.9 to 13.7
Highland Mobile Home Park	Bishop	1,260	56 to 64	3.3 to 3.7
Gerber Las Flores CSD	Gerber	1,200	155 to 226	9.1 to 13.2
Malaga County Water District	Fresno	1,200	43 to 115	2.5 to 6.7
Phoenix Lake Estates Cc MWC	Standard	1,168	130 to 257	7.6 to 15
Olympic Valley PSD	Olympic Valley	1,165	44 to 86	2.6 to 5
Sundale Mutual Water Company A, B	Lancaster	1,155	73 to 175	4.3 to 10.2
Laton Community Services District	Laton	1,151	30 to 100	1.8 to 5.8
Sonora Meadows Mutual WTR Co	Sonora	1,123	39 to 89	2.3 to 5.2
Big Basin Water Company	Irvine	1,120	35 to 160	2 to 9.4
Wild Wings Golf Community	Woodland	1,115	28 to 65	1.6 to 3.8
City of Modesto - South Turlock	Modesto	1,109	81 to 138	4.7 to 8.1
Bakman Water - Rolling Hills	Fresno	1,107	51 to 61	3 to 3.6
North Edwards WD	North Edwards	1,105	61 to 310	3.6 to 18.1
Knights Landing Svc. Dist.	Woodland	1,099	86 to 360	5 to 21.1
San Joaquin County - Raymus Village	Stockton	1,086	167 to 206	9.8 to 12
Waterford - River Pointe	Waterford	1,079	69 to 121	4 to 7.1
Bodega Bay Public Utility District	Bodega Bay	1,069	128 to 514	7.5 to 30.1
Forest Lakes MWC	Felton	1,067	11 to 478	0.6 to 27.9
Thunderbird CWD	Apple Valley	1,056	160 to 260	9.4 to 15.2
Cal Am - Goldside	Sacramento	1,053	81 to 301	4.7 to 17.6
California - American Geyserville (Puc)	Sacramento	1,050	137 to 185	8 to 10.8
Indian Creek CSD	Bishop	1,030	48 to 62	2.8 to 3.6
Kenwood Village Water Company (Puc)	Santa Rosa	1,029	165 to 215	9.6 to 12.6
Averydale MWC	Lancaster	1,026	79 to 125	4.6 to 7.3
Baker Community Services District	Baker	1,000	93 to 220	5.4 to 12.9
China Lake Naval Air Weapons Station	China Lake	1,000	3.9 to 145	0.2 to 8.5
City of Loyalton	Loyalton	983	110 to 170	6.4 to 9.9
Sultana Community Services District	Sultana	983	64 to 206	3.7 to 12
Del Oro Water Co. - Lime Saddle Marina	Chico	954	42 to 108	2.5 to 6.3
Pinon Pines MWC	Frazier Park	908	180 to 362	10.5 to 21.2
Fern Valley WD	Idyllwild	900	14 to 68	0.8 to 3.9
Valley Springs PUD	Valley Springs	900	146 to 210	8.5 to 12.3
California Water Service Co - Leona Valley	San Jose	895	91 to 370	5.3 to 21.6
Madison Service Dist	Madison	876	150 to 320	8.8 to 18.7
Juniper Riviera CWD	Apple Valley	858	58 to 110	3.4 to 6.4
McKinney Water District	Folsom	853	53 to 72	3.1 to 4.2
Apple Valley Foothill CWD	Apple Valley	841	150 to 210	8.8 to 12.3
Tahoe City PUD - Tahoe Swiss Village	Tahoe City	837	76 to 151	4.4 to 8.8
Tud - Apple Valley Estates	Sonora	829	135 to 210	7.9 to 12.3
Resort Improvement District #1	Whitethorn	803	7.5 to 280	0.4 to 16.4
John Latoracca Correctional Facility	Merced	800	58 to 328	3.4 to 19.2
Jubilee MWC	Lucerne Valley	759	110 to 155	6.4 to 9.1
Cws - Tulco Water Company	San Jose	716	82 to 180	4.8 to 10.5
Lake Hemet - Garner Valley	Hemet	709	6.8 to 170	0.4 to 9.9
Stockton Verde Mobile Home Park	Stockton	703	136 to 235	8 to 13.7
Yuima Municipal Water District Ida	Pauma Valley	693	130 to 600	7.6 to 35.1
Cal American - Yerba Buena	Rosemead	690	120 to 476	7 to 27.8
Tranquillity Irrigation District	Tranquillity	686	34 to 68	2 to 4
Lewiston Community Services District	Junction City	677	39 to 160	2.3 to 9.4
Lake Morena'S Oak Shores MWC	Campo	670	178 to 1380	10.4 to 80.7
Edwards AFB - Main Base	Edwards AFB	661	56 to 131	3.3 to 7.7
Grizzly Lake CSD - Delleker	Portola	657	57 to 92	3.3 to 5.4
Placer CSA - Sheridan	Auburn	653	57 to 70	3.4 to 4.1
Woodville Farm Labor Center	Visalia	646	106 to 200	6.2 to 11.7
Pleasantimes Mutual Water Co	Bethel Island	644	134 to 186	7.8 to 10.8
Diamond A Mutual Water Company	Sonoma	640	110 to 160	6.4 to 9.4
Yosemite NPS - El Portal	Yosemite Np	635	34 to 79	2 to 4.6
Mineral County Water District	Mineral	634	9 to 93	0.5 to 5.4
Plainview Mutual Water Company	Strathmore	617	68 to 140	3.9 to 8.2
Cedarville County Water Dist.	Cedarville	600	97 to 127	5.7 to 7.4
Mesa Dunes Mobile Home Estates	Arroyo Grande	600	110 to 135	6.4 to 7.9
San Francisco Regional Water System	Burlingame	600	3.6 to 297	0.2 to 17.4
Sierra Highland CSD	Bishop	600	42 to 63	2.5 to 3.7
Waterford - Hickman	Modesto	597	15 to 82	0.9 to 4.8
Golden State Water Co - Lucerne	Apple Valley	590	140 to 220	8.2 to 12.9
Carmel Riviera MWC	Carmel	584	75 to 188	4.4 to 11
Stinson Beach County WTR Dist	Stinson Beach	583	96 to 160	5.6 to 9.4
River Pines PUD	River Pines	574	155 to 265	9.1 to 15.5
Blythe - Mesa Ranch	Blythe	568	145 to 495	8.5 to 28.9
Banning Hts. Mutual Water Co.	Banning	567	110 to 155	6.4 to 9.1
Jacumba Community SD	Jacumba	561	170 to 310	9.9 to 18.1
Glen Eden Sun Club	Corona	560	180 to 200	10.5 to 11.7
Odd Fellows Recreation Club	Guerneville	557	72 to 210	4.2 to 12.3
Vineyard Rv Park	Vacaville	550	120 to 180	7 to 10.5

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.

401 to 500 of 759, by people served

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