Water hardness, indicated by the level of dissolved minerals such as calcium and magnesium, varies across the diverse landscapes of California. Situated along the western coast of the U.S., California’s water hardness levels are highly variable, reflecting the complex geological makeup of the state.
In California, the water hardness can range from very soft in certain areas to extremely hard in others, mirroring the varied geology and the sources of the state’s water. For example, regions with rapid runoff from mountain snowmelt, like those in the Sierra Nevada, typically have softer water because the water has limited interaction with mineral-rich soils or rocks. On the other hand, areas with a great deal of sedimentary rock, such as parts of the Central Valley, may have harder water due to higher concentrations of dissolved minerals like calcium and magnesium.
These differences in water hardness across California not only affect the taste of the water but also have implications for the performance of soaps and detergents. Additionally, there is an impact on the maintenance of plumbing systems and the longevity of household appliances. Given California’s vast size and geological diversity, water hardness levels are far from consistent and can change markedly, underscoring the importance of localized water treatment methods and continual water quality monitoring.
The data provided demonstrates a range of water hardness levels across various cities in California, measured in parts per million (ppm) and Grains Per Gallon (gpg). For example, Santa Clarita and Oxnard have particularly high water hardness levels, reaching upwards of 437.5 ppm, 25.53 gpg. In contrast, cities such as San Francisco and Anaheim report remarkably soft water, with measurements as low as 18.0 ppm, 1.05 gpg. There is, however, a noteworthy lack of water hardness data for certain areas including Elk Grove and Rancho Cucamonga, as no current figures are available for these cities.
City | Hardness ppm (mg/L) | Hardness gpg | Information Source | Notes |
Los Angeles | 195.0 | 11.4 | Link | Took mean of six sources |
San Diego | 260.7 | 15.2 | Link | Took mean of three treatment plants |
San Jose | 238.2 | 13.9 | Link | Took mean of six treatment plants |
San Francisco | 32.0 | 1.9 | Link | |
Fresno | 108.0 | 6.3 | Link | |
Sacramento | 141.0 | 8.2 | Link | |
Long Beach | 121.0 | 7.1 | Link | Used the “Blended Zone” number which includes water purchased from other systems and distributed through LB |
Oakland | 63.8 | 3.7 | Link | Took mean of three treatment plants serving Oakland city |
Bakersfield | 68.4 | 4.0 | Link | Took mean of two listed sources |
Anaheim | 18.0 | 1.1 | Link | |
Stockton | 92.0 | 5.4 | Link | Took mean of two listed sources |
Riverside | 202.0 | 11.8 | Link | |
Santa Ana | 248.0 | 14.5 | Link | |
Irvine | 226.0 | 13.2 | Link | Took mean of three listed sources |
Chula Vista | 220.8 | 12.9 | Link | |
Fremont | 148.0 | 8.6 | Link | Took blended water average |
Santa Clarita | 420.0 | 24.5 | Link | Took only Santa Clarita Water Division from SCV Water Report |
San Bernardino | 249.4 | 14.6 | Link | |
Modesto | 211.0 | 12.3 | Link | |
Moreno Valley | 197.3 | 11.5 | Link | Took mean of four listed sources for Moreno Valley area |
Fontana | 149.7 | 8.7 | Link | |
Oxnard | 437.5 | 25.6 | Link | |
Huntington Beach | 161.0 | 9.4 | Link | |
Glendale | 360.3 | 21.0 | Link | Took mean of seven listed sources for Glendale |
Elk Grove | n/a | n/a | Link | Corrupted PDF files for last 3 years of CCRs when checked |
Ontario | 138.0 | 8.1 | Link | Took mean of two listed sources |
Santa Rosa | 112.0 | 6.5 | Link | |
Rancho Cucamonga | n/a | n/a | Link | Website Down when checked |
Oceanside | 218.8 | 12.8 | Link | Took mean of five listed sources |
Garden Grove | 265.0 | 15.5 | Link | |
Lancaster | 82.5 | 4.8 | Link | Took mean of two listed sources |
Palmdale | 115.0 | 6.7 | Link | Took mean of two listed sources |
Salinas | 320.0 | 18.7 | Link | |
Hayward | 32.0 | 1.9 | Link | |
Corona | 162.0 | 9.5 | Link | Used treated average system water value |
Sunnyvale | 144.3 | 8.4 | Link | Took mean of three listed source |
Roseville | 78.5 | 4.6 | Link | Took mean of two listed sources |
Escondido | 265.0 | 15.5 | Link | |
Pomona | 199.8 | 11.7 | Link | Took mean of four listed sources |
Torrance | 211.0 | 12.3 | Link | Purchases from Metro Water Dist. of SoCal Took average of 5 sources, not clear what the exact blend was for Torrance |
Visalia | 77.0 | 4.5 | Link | |
Fullerton | 278.5 | 16.3 | Link | |
Orange | 17.0 | 1.0 | Link | |
Victorville | 28.1 | 1.6 | Link | |
Pasadena | 276.0 | 16.0 | Link | |
Santa Clara | 296.0 | 17.3 | Link | |
Simi Valley | 280.0 | 16.4 | Link | |
Thousand Oaks | 140.4 | 8.2 | Link | Used weighted mean of the two sources that account for 92% of supply, although others are listed |
Vallejo | 188.0 | 11.0 | Link | |
Concord | 119.0 | 7.0 | Link | Part of Contra Costa Water District |
Clovis | 120.4 | 7.0 | Link | |
Fairfield | 162.0 | 9.5 | Link | |
Berkeley | 63.8 | 3.7 | Link | Same water district as Oakland, used those numbers |
Richmond | 63.8 | 3.7 | Link | Same water district as Oakland, used those numbers |
Carlsbad | 197.9 | 11.6 | Link | |
Antioch | 110.0 | 6.4 | Link | Took mean of two sources |
Murrieta | 116.4 | 6.8 | Link | |
Downey | 267.0 | 15.6 | Link | |
Temecula | 218.5 | 12.8 | Link | Uses Rancho California Water (https://temeculaca.gov/754/Utilities) |
Costa Mesa | 278.5 | 16.3 | Link | |
San Buenaventura (Ventura) | 479.0 | 28.0 | Link | Took mean of three sources |
Santa Maria | 275.0 | 16.1 | Link | Took mean of two “Blend” values |
West Covina | 280.0 | 16.4 | Link | West Covina uses multiple water sources, took the Covina report as that’s the closest city geographically (https://www.westcovina.org/departments/community-development/engineering-division/water-utilities-emergency-numbers) |
Jurupa Valley | 168.0 | 9.8 | Link | |
El Monte | 260.0 | 15.2 | Link | |
Menifee | 197.3 | 11.5 | Link | Same system as Moreno Valley |
El Cajon | 238.0 | 14.0 | Link | El Cajon served by Helix Water (https://www.elcajon.gov/your-government/departments/public-works/utilities/other-utilities) |
Burbank | 315.0 | 18.4 | Link | |
Inglewood | 235.0 | 13.7 | Link | |
Rialto | 158.0 | 9.2 | Link | Used City of Rialto number only |
Vacaville | 183.3 | 10.7 | Link | |
Chico | 120.0 | 7.0 | Link | |
San Mateo | 34.0 | 2.0 | Link | |
Daly City | 32.0 | 1.9 | Link | |
Hesperia | 74.6 | 4.4 | Link | |
Norwalk | 266.0 | 15.5 | Link | |
Vista | 214.4 | 12.5 | Link | Took mean of five sources |
Tracy | 143.0 | 8.4 | Link | Took mean of three sources |
San Marcos | 226.7 | 13.2 | Link | |
Compton | 218.6 | 12.8 | Link | |
Carson | 171.5 | 10.0 | Link | Served by Rancho Domingo |
Redding | 70.3 | 4.1 | Link | Took mean of two sources |
Chino | 170.9 | 10.0 | Link | Took mean of three sources |
Mission Viejo | 278.0 | 16.2 | Link | Covered by Santa Margarita Water District (https://cityofmissionviejo.org/water-conservation) |
South Gate | 227.1 | 13.3 | Link | |
Santa Monica | 277.3 | 16.2 | Link | Took mean of listed sources |
Hemet | 155.0 | 9.1 | Link | |
Indio | 148.5 | 8.7 | Link | |
Westminster | 262.5 | 15.3 | Link | |
Merced | 114.0 | 6.7 | Link | |
San Leandro | 63.8 | 3.7 | Link | Covered under same district as Oakland |
Santa Barbara | 287.0 | 16.8 | Link | |
Citrus Heights | 74.0 | 4.3 | Link | |
San Ramon | 235.0 | 13.7 | Link | |
Livermore | 234.0 | 13.7 | Link | |
Hawthorne | 236.5 | 13.8 | Link | |
Manteca | 136.0 | 7.9 | Link | |
Lake Forest | 278.0 | 16.2 | Link | Covered by El Toro Water District |
Whittier | 230.3 | 13.5 | Link | |
Newport Beach | 278.0 | 16.2 | Link |
ppm = Parts Per Million
mg/L = Milligrams Per Liter
gpg = Grains Per Gallon
Hard water can cause issues such as mineral buildup in plumbing and appliances, reduce the efficacy of soaps and detergents, and affect the taste of the water. A tried and true solution is the use of a water softener. A water softener, like the ones from DROP, could be a worthwhile investment.
These devices work by replacing the calcium and magnesium ions that cause hardness with sodium ions, resulting in softer water. With innovative features, easy installation, and efficient operation, DROP smart water softeners provide a solution to hard water issues, extending the lifespan of appliances, improving water taste, enhancing soap effectiveness, reducing scale build-up, and increasing the overall water efficiency in your home.