California water hardness, by utility.

2,456 California utilities serving 36 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

759 utilities serving 28 million people have water in more than one band. Among those in one band, very hard water reaches the most people: 718 utilities serving 5.6 million.

The largest, Los Angeles - City, Dept. of Water & Power, is moderately hard to very hard depending on the source, 94 to 544 mg/L (5.5 to 31.8 grains per gallon).

Very hard

Above 180 mg/L (10.5 grains per gallon). 718 utilities serving 5.6 million people; the 25 largest are here.

California utilities: very hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Irvine Ranch Water District	Irvine	450,323	214 to 293	12.5 to 17.1
City of Anaheim	Anaheim	350,254	318	18.6
Glendale - City, Water Dept.	Glendale	192,212	370	21.6
Sweetwater Authority	Chula Vista	184,915	193	11.3
City of Garden Grove	Garden Grove	174,226	331	19.4
City of Sunnyvale	Sunnyvale	157,566	280	16.4
City of Fullerton	Fullerton	140,054	212	12.4
Great Oaks WC Inc	San Jose	112,582	305	17.8
Ventura Water Department	Ventura	112,285	517	30.2
City of Santa Maria Utilities Department	Santa Maria	112,208	500	29.2
San Bernardino Valley WD	San Bernardino	109,608	248	14.5
Burbank - City, Water Dept.	Burbank	106,146	330	19.3
California Water Service Co. - Herm/Redo	San Jose	100,072	415	24.3
City of San Jose - Evg/Edv/Coy	San Jose	99,783	320	18.7
Ventura Wwd No. 8 - Simi Valley	Simi Valley	94,736	527	30.8
Olivenhain MWD	Encinitas	86,458	227	13.3
Goleta Water District	Goleta	85,535	485	28.4
Yorba Linda Water District	Placentia	84,292	344	20.1
City of Mountain View	Mountain View	81,340	269	15.7
City of Pleasanton	Pleasanton	76,689	343	20.1
Liberty Utilities - Bellflower - Norwalk	Downey	72,472	290	17
Lynwood - City, Water Dept.	Lynwood	66,967	270	15.8
Suburban Water Systems - Whittier	Covina	66,565	243	14.2
City of Watsonville	Watsonville	65,231	230	13.5
Brentwood	Brentwood	64,513	369	21.6

All 718 with very hard water

Hard

121 to 180 mg/L (7.1 to 10.5 grains per gallon). 240 utilities serving 678,596 people; the 25 largest are here.

California utilities: hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
City of Corona	Corona	169,380	146	8.5
City of Milpitas	Milpitas	81,915	144	8.4
Las Virgenes MWD	Calabasas	77,562	141	8.2
Suburban Water Systems - la Mirada	Covina	57,240	160	9.3
Gswc - Culver City	Santa Fe Springs	38,233	170	9.9
Suisun - Solano Water Authority	Vacaville	29,105	167	9.8
Liberty Utilities - Compton	Downey	26,316	155	9.1
Town of Windsor	Windsor	25,561	128	7.5
Menlo Park Municipal Water	Menlo Park	22,362	170	9.9
City of la Palma	La Palma	15,948	146	8.5
City of Bell Gardens	Bell Gardens	11,413	140	8.2
City of Cloverdale	Cloverdale	8,710	161	9.4
Highlands Mutual Water Company	Clearlake	7,772	140	8.2
Konocti County Water District	Clearlake	5,928	154	9
Sweetwater Springs CWD - Guerneville	Guerneville	5,156	160	9.4
Blue Lake Springs Mut WTR	Arnold	4,822	165	9.6
MT. Konocti Mutual Water Company	Kelseyville	4,360	157	9.2
Russian River County Water District	Forestville	4,150	130	7.6
Lake County CSA 21 - North Lakeport	Lakeport	4,046	141	8.3
California State Prison - Solano	Vacaville	3,882	170	9.9
Commerce - City, Water Dept.	Montebello	3,598	152	8.9
Sweetwater Springs CWD - Monte Rio	Guerneville	3,531	170	9.9
Marygold MWC	Bloomington	3,155	145	8.5
Nice Mutual Water Company	Nice	2,929	122	7.1
Land Projects Mutual Water Co.	Lancaster	2,800	168	9.8

All 240 with hard water

Moderately hard

61 to 120 mg/L (3.6 to 7 grains per gallon). 414 utilities serving 465,877 people; the 25 largest are here.

California utilities: moderately hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
North Marin Water District	Novato	61,691	111	6.5
City of Lincoln	Lincoln	56,268	87	5.1
City of Mountain House	Mountain House	26,400	84	4.9
Linda County Water District	Marysville	21,654	70	4.1
Twentynine Palms Water District	Twentynine Palms	18,795	67	3.9
City of American Canyon	American Canyon	18,423	98	5.7
Rosamond CSD	Rosamond	18,150	99	5.8
Coalinga - City	Coalinga	17,277	105	6.1
City of Red Bluff	Red Bluff	14,286	84	4.9
City of California City	California City	14,198	102	6
City of Avenal	Avenal	13,696	99	5.8
Plumas Lake	Olivehurst	11,374	100	5.8
Del Oro Water Co. - Paradise Pines	Chico	10,738	70	4.1
Ccwd - Jenny Lind	San Andreas	9,861	78	4.6
City of Susanville	Susanville	7,811	84	4.9
City of Dos Palos	Dos Palos	7,452	71	4.2
City of Huron	Huron	7,306	91	5.3
Los Angeles Cwwd 36 - Val Verde	Alhambra	6,712	97	5.7
City of Calistoga	Calistoga	5,610	80	4.7
Redwood Valley County Water District	Ukiah	5,200	78	4.5
Denair Community Services District	Denair	5,093	95	5.5
Northstar CSD - Martis Valley	Truckee	4,432	72	4.2
Lockeford Community Serv. Dist.	Lockeford	3,572	96	5.6
Valley State Prison	Chowchilla	3,151	94	5.5
Seaside Municipal Water System	Seaside	2,800	75	4.4

All 414 with moderately hard water

Soft

Up to 60 mg/L (3.5 grains per gallon). 325 utilities serving 910,291 people; the 25 largest are here.

California utilities: soft water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
El Dorado ID - Main	Placerville	128,408	12	0.7
Folsom, City of - Main	Folsom	80,969	18	1.1
City of Yuba City	Yuba City	70,256	55	3.2
City of Hanford	Hanford	62,127	11	0.6
City of West Sacramento	West Sacramento	55,991	51	3
SCWA Mather - Sunrise	Sacramento	32,812	53	3.1
San Juan Water District	Granite Bay	29,738	17	1
Placer CWA - Auburn/Bowman	Auburn	27,317	14	0.8
City of Lemoore	Lemoore	27,185	3.9	0.2
South Feather W&P - Miners Ranch	Oroville	22,638	27	1.6
Nevada ID - E. George, Banner Mountain	Grass Valley	17,154	13	0.7
City of Crescent City	Crescent City	15,202	59	3.5
Nevada ID - Loma Rica	Grass Valley	14,072	12	0.7
Sbdno County Service Area 70j	San Bernardino	12,895	18	1
Ccwd - Ebbetts Pass	San Andreas	11,545	8.2	0.5
City of Shasta Lake	Shasta Lake 4510007	10,371	53	3.1
Cal Am - West Placer	Sacramento	9,547	26	1.5
City of Orange Cove	Orange Cove	9,525	11	0.6
Georgetown Divide PUD	Georgetown	9,434	9.1	0.5
Nevada ID - Lake Wildwood	Grass Valley	9,108	15	0.9
Awa Buckhorn Plant	Sutter Creek	8,791	5.9	0.3
Earlimart PUD	Earlimart	7,679	52	3
Folsom State Prison	Represa	7,399	19	1.1
Awa, Ione	Jackson	7,227	12	0.7
City of Fort Bragg	Fort Bragg	7,117	36	2.1

All 325 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. 759 utilities serving 28 million people; the 25 largest are here.

California utilities: varies water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Los Angeles - City, Dept. of Water & Power	Los Angeles	3,875,566	94 to 544	5.5 to 31.8
East Bay MUD	Oakland	1,468,000	17 to 120	1 to 7
City of San Diego	San Diego	1,408,937	113 to 619	6.6 to 36.2
San Jose Water	San Jose	1,039,920	112 to 512	6.5 to 29.9
SFPUC City Distribution Division	Burlingame	848,019	9 to 256	0.5 to 14.9
City of Fresno	Fresno	545,970	8.8 to 390	0.5 to 22.8
City of Sacramento Main	Sacramento	527,979	15 to 320	0.9 to 18.7
Long Beach Utilities Department	Long Beach	466,772	11 to 280	0.6 to 16.4
Alameda County Water District	Fremont	344,000	40 to 138	2.3 to 8.1
City of Santa Ana	Santa Ana	316,184	125 to 395	7.3 to 23.1
City of Riverside	Riverside	302,776	55 to 395	3.2 to 23.1
Santa Clarita Valley Water Agency	Newhall	292,014	120 to 568	7 to 33.2
Helix Water District	La Mesa	277,918	130 to 353	7.6 to 20.6
Gswc - Southwest	Hawthorne	277,740	120 to 280	7 to 16.4
Coachella Vwd: Cove Community	Palm Desert	270,000	7.5 to 326	0.4 to 19.1
Cws - Bakersfield	San Jose	268,129	55 to 325	3.2 to 19
San Gabriel Valley Water Co. - El Monte	El Monte	240,000	91 to 340	5.3 to 19.9
San Gabriel Valley WC - Fontana	Fontana	228,270	90 to 234	5.3 to 13.7
City of Modesto	Modesto	218,915	35 to 388	2 to 22.7
San Bernardino City	San Bernardin0	214,665	120 to 320	7 to 18.7
Cucamonga Valley Water District	Rancho Cucuamonga	213,375	86 to 244	5 to 14.3
Contra Costa Water District	Concord	210,500	52 to 132	3 to 7.7
Los Angeles Cwwd 40 Reg 4 & 34 Lancaster	Alhambra	208,129	14 to 240	0.8 to 14
City of Huntington Beach	Huntington Beach	201,000	62 to 264	3.6 to 15.4
Sacramento Suburban Water District	Sacramento	194,444	54 to 370	3.2 to 21.6

All 759 whose water varies

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.

Very hard

Hard

Moderately hard

Soft

Varies

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