Water Hardness in California
Across 772 measured cities — with 243 more covered by labeled county-level estimates — California's median tap water hardness is 98.4 mg/L (5.8 gpg): moderately hard on the USGS scale. Below: every covered city, the state's hardest and softest water, and the geology that explains it.
Data updated July 6, 2026. Sources: utility-reported water quality data and USGS/EPA Water Quality Portal samples.
State Median
98.4
mg/L (5.8 gpg), measured cities
Measured Range
3.3-604.0
mg/L across measured cities
Measured Cities
772
utility-reported or computed values
County Estimates
243
24% of covered cities
California Cities by Hardness Category
Measured cities only — labeled county estimates never enter the category counts or the median.
| Category | Range | Measured cities | Share |
|---|---|---|---|
| Soft | 0-60 mg/L | 237 | 30.7% |
| Moderately hard | 60-120 mg/L | 244 | 31.6% |
| Hard | 120-180 mg/L | 167 | 21.6% |
| Very hard | >180 mg/L | 124 | 16.1% |
Hardest and Softest Water in California
Measured values only; labeled county estimates and values under active dispute never rank.
Hardest water in California
- Los Berros — 604.0 mg/L (35.3 gpg), very hard
- Nipomo — 604.0 mg/L (35.3 gpg), very hard
- Saticoy — 505.0 mg/L (29.5 gpg), very hard
- San Buenaventura (Ventura) — 476.8 mg/L (27.9 gpg), very hard
- Tehachapi — 363.0 mg/L (21.2 gpg), very hard
Softest water in California
- La Canada — 3.3 mg/L (0.2 gpg), soft
- La Crescenta-Montrose — 3.3 mg/L (0.2 gpg), soft
- Lodi — 4.3 mg/L (0.3 gpg), soft
- McFarland — 5.0 mg/L (0.3 gpg), soft
- Westhaven-Moonstone — 7.7 mg/L (0.5 gpg), soft
Every Covered City in California
All 1,015 covered California cities, sorted by population served. "County estimate" rows are labeled context values from USGS/EPA Water Quality Portal county sampling — they never enter the median above. City names link to each city's full water quality page.
| City | Hardness (mg/L) | gpg | Category | Data |
|---|---|---|---|---|
| Burbank | 133.3 | 7.8 | Hard | Utility-reported |
| West Carson | 118.6 | 6.9 | Moderately hard | Utility-reported |
| Lomita | 121.0 | 7.1 | Hard | Utility-reported |
| Florence-Graham | 121.0 | 7.1 | Hard | Utility-reported |
| Ladera Heights | 122.3 | 7.2 | Hard | Utility-reported |
| Willowbrook | 121.0 | 7.1 | Hard | Utility-reported |
| Culver City | 121.5 | 7.1 | Hard | Utility-reported |
| San Fernando | 121.0 | 7.1 | Hard | Utility-reported |
| View Park-Windsor Hills | 121.8 | 7.1 | Hard | Utility-reported |
| Los Angeles | 121.0 | 7.1 | Hard | Utility-reported |
| Beverly Hills | 121.0 | 7.1 | Hard | Utility-reported |
| Marina del Rey | 121.0 | 7.1 | Hard | Utility-reported |
| West Hollywood | 121.0 | 7.1 | Hard | Utility-reported |
| Hayward | 43.7 | 2.6 | Soft | Utility-reported |
| El Sobrante | 47.8 | 2.8 | Soft | Utility-reported |
| San Diego | 225.0 | 13.2 | Very hard | Utility-reported |
| El Cerrito | 50.8 | 3.0 | Soft | Utility-reported |
| Pleasant Hill | 40.5 | 2.4 | Soft | Utility-reported |
| Contra Costa Centre | 40.1 | 2.4 | Soft | Utility-reported |
| Shell Ridge | 40.1 | 2.4 | Soft | Utility-reported |
| Walnut Creek | 40.1 | 2.4 | Soft | Utility-reported |
| Ashland | 33.1 | 1.9 | Soft | Utility-reported |
| Cherryland | 33.1 | 1.9 | Soft | Utility-reported |
| Fairview | 33.1 | 1.9 | Soft | Utility-reported |
| San Lorenzo | 33.1 | 1.9 | Soft | Utility-reported |
| San Ramon | 43.7 | 2.6 | Soft | Utility-reported |
| Coronado | 160.1 | 9.4 | Hard | Utility-reported |
| Bayview | 34.5 | 2.0 | Soft | Utility-reported |
| Santee | 160.2 | 9.4 | Hard | Utility-reported |
| Alameda | 33.7 | 2.0 | Soft | Utility-reported |
| Moraga | 33.7 | 2.0 | Soft | Utility-reported |
| Castro Valley | 33.7 | 2.0 | Soft | Utility-reported |
| Acalanes Ridge | 33.7 | 2.0 | Soft | Utility-reported |
| Alamo | 33.7 | 2.0 | Soft | Utility-reported |
| Albany | 33.7 | 2.0 | Soft | Utility-reported |
| Berkeley | 33.7 | 2.0 | Soft | Utility-reported |
| Blackhawk | 33.7 | 2.0 | Soft | Utility-reported |
| Camino Tassajara | 33.7 | 2.0 | Soft | Utility-reported |
| Castle Hill | 33.7 | 2.0 | Soft | Utility-reported |
| Crockett | 33.7 | 2.0 | Soft | Utility-reported |
| Danville | 33.7 | 2.0 | Soft | Utility-reported |
| Diablo | 33.7 | 2.0 | Soft | Utility-reported |
| East Richmond Heights | 33.7 | 2.0 | Soft | Utility-reported |
| Emeryville | 33.7 | 2.0 | Soft | Utility-reported |
| Hercules | 33.7 | 2.0 | Soft | Utility-reported |
| Kensington | 33.7 | 2.0 | Soft | Utility-reported |
| Lafayette | 33.7 | 2.0 | Soft | Utility-reported |
| Montalvin Manor | 33.7 | 2.0 | Soft | Utility-reported |
| Norris Canyon | 33.7 | 2.0 | Soft | Utility-reported |
| North Richmond | 33.7 | 2.0 | Soft | Utility-reported |
| Oakland | 33.7 | 2.0 | Soft | Utility-reported |
| Orinda | 33.7 | 2.0 | Soft | Utility-reported |
| Piedmont | 33.7 | 2.0 | Soft | Utility-reported |
| Pinole | 33.7 | 2.0 | Soft | Utility-reported |
| Reliez Valley | 33.7 | 2.0 | Soft | Utility-reported |
| Richmond | 33.7 | 2.0 | Soft | Utility-reported |
| Rodeo | 33.7 | 2.0 | Soft | Utility-reported |
| Rollingwood | 33.7 | 2.0 | Soft | Utility-reported |
| San Leandro | 33.7 | 2.0 | Soft | Utility-reported |
| San Miguel | 33.7 | 2.0 | Soft | Utility-reported |
| San Pablo | 33.7 | 2.0 | Soft | Utility-reported |
| Saranap | 33.7 | 2.0 | Soft | Utility-reported |
| Tara Hills | 33.7 | 2.0 | Soft | Utility-reported |
| Fresno | 12.1 | 0.7 | Soft | Computed from Ca+Mg |
| Mayfair | 9.6 | 0.6 | Soft | Computed from Ca+Mg |
| Cupertino | 185.8 | 10.9 | Very hard | Utility-reported |
| San Jose | 184.6 | 10.8 | Very hard | Utility-reported |
| Murrieta | 132.3 | 7.7 | Hard | Utility-reported |
| Riverside | 111.9 | 6.5 | Moderately hard | Utility-reported |
| Los Gatos | 178.0 | 10.4 | Hard | Utility-reported |
| Alum Rock | 178.0 | 10.4 | Hard | Utility-reported |
| Cambrian Park | 178.0 | 10.4 | Hard | Utility-reported |
| Campbell | 178.0 | 10.4 | Hard | Utility-reported |
| East Foothills | 178.0 | 10.4 | Hard | Utility-reported |
| Fruitdale | 178.0 | 10.4 | Hard | Utility-reported |
| Lexington Hills | 178.0 | 10.4 | Hard | Utility-reported |
| Monte Sereno | 178.0 | 10.4 | Hard | Utility-reported |
| Saratoga | 178.0 | 10.4 | Hard | Utility-reported |
| Compton | 140.0 | 8.2 | Hard | Utility-reported |
| San Francisco | 25.1 | 1.5 | Soft | Utility-reported |
| Temecula | 139.0 | 8.1 | Hard | Utility-reported |
| Canyon Lake | 117.5 | 6.9 | Moderately hard | Utility-reported |
| Santa Ana | 149.9 | 8.8 | Hard | Utility-reported |
| Sacramento | 44.9 | 2.6 | Soft | Utility-reported |
| Hemet | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Moreno Valley | 122.3 | 7.2 | Hard | Utility-reported |
| March ARB | 122.3 | 7.2 | Hard | Utility-reported |
| Mead Valley | 122.3 | 7.2 | Hard | Utility-reported |
| San Jacinto | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Spring Valley | 189.4 | 11.1 | Very hard | Utility-reported |
| La Presa | 189.4 | 11.1 | Very hard | Utility-reported |
| East Hemet | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Valle Vista | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Beaumont | 123.0 | 7.2 | Hard | Utility-reported |
| Fontana | 92.0 | 5.4 | Moderately hard | Utility-reported |
| Perris | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Lakeview | 120.5 | 7.0 | Hard | Utility-reported |
| Nuevo | 120.5 | 7.0 | Hard | Utility-reported |
| Newport Beach | 102.2 | 6.0 | Moderately hard | Utility-reported |
| French Valley | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Good Hope | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Green Acres | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Homeland | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Menifee | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Romoland | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Sage | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Winchester | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Orange | 117.3 | 6.9 | Moderately hard | Utility-reported |
| Industry | 123.0 | 7.2 | Hard | Utility-reported |
| Costa Mesa | 96.1 | 5.6 | Moderately hard | Utility-reported |
| Norco | 98.7 | 5.8 | Moderately hard | Utility-reported |
| Fruitridge Pocket | 25.1 | 1.5 | Soft | Utility-reported |
| Lemon Hill | 25.1 | 1.5 | Soft | Utility-reported |
| Lake Forest | 109.4 | 6.4 | Moderately hard | Utility-reported |
| Tustin | 116.8 | 6.8 | Moderately hard | Utility-reported |
| Laguna Woods | 108.4 | 6.3 | Moderately hard | Utility-reported |
| Hawaiian Gardens | 171.0 | 10.0 | Hard | County estimate |
| Laguna Beach | 98.2 | 5.7 | Moderately hard | Utility-reported |
| Casa de Oro-Mount Helix | 212.5 | 12.4 | Very hard | Utility-reported |
| Rancho San Diego | 212.5 | 12.4 | Very hard | Utility-reported |
| Rialto | 89.0 | 5.2 | Moderately hard | Utility-reported |
| West Covina | 170.4 | 10.0 | Hard | Utility-reported |
| Bakersfield | 33.9 | 2.0 | Soft | Utility-reported |
| Hacienda Heights | 116.6 | 6.8 | Moderately hard | Utility-reported |
| Signal Hill | 171.0 | 10.0 | Hard | County estimate |
| Modjeska | 99.9 | 5.8 | Moderately hard | Utility-reported |
| Long Beach | 171.0 | 10.0 | Hard | County estimate |
| Irvine | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Silverado | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Bloomington | 95.9 | 5.6 | Moderately hard | Utility-reported |
| Rancho Cucamonga | 68.3 | 4.0 | Moderately hard | Utility-reported |
| La Puente | 109.6 | 6.4 | Moderately hard | Utility-reported |
| Anaheim | 273.6 | 16.0 | Very hard | Utility-reported |
| West Puente Valley | 109.2 | 6.4 | Moderately hard | Utility-reported |
| Carson | 140.0 | 8.2 | Hard | Utility-reported |
| San Bernardino | 79.2 | 4.6 | Moderately hard | Utility-reported |
| Temescal Valley | 127.8 | 7.5 | Hard | Utility-reported |
| Bonita | 215.7 | 12.6 | Very hard | Utility-reported |
| Chula Vista | 215.7 | 12.6 | Very hard | Utility-reported |
| Highgrove | 99.0 | 5.8 | Moderately hard | Utility-reported |
| Lakeside | 163.6 | 9.6 | Hard | Utility-reported |
| Palm Springs | 137.6 | 8.1 | Hard | Utility-reported |
| Hawthorne | 188.6 | 11.0 | Very hard | Utility-reported |
| Home Gardens | 99.0 | 5.8 | Moderately hard | Utility-reported |
| Mission Viejo | 159.0 | 9.3 | Hard | Utility-reported |
| Woodcrest | 99.0 | 5.8 | Moderately hard | Utility-reported |
| Santa Fe Springs | 60.8 | 3.6 | Moderately hard | Utility-reported |
| Ontario | 104.4 | 6.1 | Moderately hard | Utility-reported |
| Carmichael | 74.0 | 4.3 | Moderately hard | Utility-reported |
| Mountain View | 134.5 | 7.9 | Hard | Utility-reported |
| Rosemead | 46.5 | 2.7 | Soft | Utility-reported |
| San Juan Capistrano | 157.6 | 9.2 | Hard | Utility-reported |
| Lawndale | 188.4 | 11.0 | Very hard | Utility-reported |
| Whittier | 74.8 | 4.4 | Moderately hard | Utility-reported |
| Bostonia | 164.6 | 9.6 | Hard | Utility-reported |
| El Cajon | 164.6 | 9.6 | Hard | Utility-reported |
| Granite Hills | 164.6 | 9.6 | Hard | Utility-reported |
| Stockton | 10.5 | 0.6 | Soft | Computed from Ca+Mg |
| Cathedral City | 137.6 | 8.1 | Hard | Utility-reported |
| Rancho Mirage | 137.6 | 8.1 | Hard | Utility-reported |
| Country Club | 10.2 | 0.6 | Soft | Computed from Ca+Mg |
| Inglewood | 194.6 | 11.4 | Very hard | Utility-reported |
| San Marcos | 177.6 | 10.4 | Hard | Utility-reported |
| Indio | 100.2 | 5.9 | Moderately hard | Utility-reported |
| Jurupa Valley | 122.2 | 7.2 | Hard | Utility-reported |
| El Monte | 48.1 | 2.8 | Soft | Utility-reported |
| Torrance | 111.8 | 6.5 | Moderately hard | Computed from Ca+Mg |
| Fremont | 65.1 | 3.8 | Moderately hard | Utility-reported |
| Union City | 65.1 | 3.8 | Moderately hard | Utility-reported |
| Newark | 65.1 | 3.8 | Moderately hard | Utility-reported |
| Palmdale | 61.8 | 3.6 | Moderately hard | Utility-reported |
| Walnut | 210.4 | 12.3 | Very hard | Utility-reported |
| Baldwin Park | 60.6 | 3.5 | Moderately hard | Utility-reported |
| Muscoy | 72.0 | 4.2 | Moderately hard | Utility-reported |
| Montebello | 67.4 | 3.9 | Moderately hard | Utility-reported |
| West Whittier-Los Nietos | 74.8 | 4.4 | Moderately hard | Utility-reported |
| Crest | 266.1 | 15.6 | Very hard | Utility-reported |
| Monterey Park | 67.4 | 3.9 | Moderately hard | Utility-reported |
| Coachella | 99.2 | 5.8 | Moderately hard | Utility-reported |
| Antioch | 82.0 | 4.8 | Moderately hard | Utility-reported |
| Winter Gardens | 150.5 | 8.8 | Hard | Utility-reported |
| Arcadia | 54.4 | 3.2 | Soft | Utility-reported |
| Escondido | 171.1 | 10.0 | Hard | Utility-reported |
| Citrus Heights | 82.3 | 4.8 | Moderately hard | Utility-reported |
| West Rancho Dominguez | 185.0 | 10.8 | Very hard | Utility-reported |
| East San Gabriel | 191.7 | 11.2 | Very hard | Utility-reported |
| Bakersfield Country Club | 36.9 | 2.2 | Soft | Utility-reported |
| Carlsbad | 150.2 | 8.8 | Hard | Utility-reported |
| Pomona | 138.5 | 8.1 | Hard | Utility-reported |
| Santa Clarita | 229.5 | 13.4 | Very hard | Utility-reported |
| South San Gabriel | 33.7 | 2.0 | Soft | Utility-reported |
| Bermuda Dunes | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Antelope | 90.0 | 5.3 | Moderately hard | Utility-reported |
| La Mesa | 150.0 | 8.8 | Hard | Utility-reported |
| Lemon Grove | 150.0 | 8.8 | Hard | Utility-reported |
| Alondra Park | 185.0 | 10.8 | Very hard | Utility-reported |
| Del Aire | 185.0 | 10.8 | Very hard | Utility-reported |
| Gardena | 185.0 | 10.8 | Very hard | Utility-reported |
| Lennox | 185.0 | 10.8 | Very hard | Utility-reported |
| West Athens | 185.0 | 10.8 | Very hard | Utility-reported |
| Westmont | 185.0 | 10.8 | Very hard | Utility-reported |
| Sky Valley | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Colton | 138.6 | 8.1 | Hard | Utility-reported |
| Pico Rivera | 45.2 | 2.6 | Soft | Utility-reported |
| Palm Desert | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Desert Palms | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Indian Wells | 113.0 | 6.6 | Moderately hard | Utility-reported |
| La Quinta | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Mecca | 113.0 | 6.6 | Moderately hard | Utility-reported |
| North Shore | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Oasis | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Thermal | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Thousand Palms | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Vista Santa Rosa | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Roseville | 18.7 | 1.1 | Soft | Utility-reported |
| Ceres | 66.5 | 3.9 | Moderately hard | Utility-reported |
| Cottonwood | 36.9 | 2.2 | Soft | Utility-reported |
| Pittsburg | 82.3 | 4.8 | Moderately hard | Utility-reported |
| Avocado Heights | 33.7 | 2.0 | Soft | Utility-reported |
| Casa Loma | 36.9 | 2.2 | Soft | Utility-reported |
| Benton Park | 36.9 | 2.2 | Soft | Utility-reported |
| East Bakersfield | 36.9 | 2.2 | Soft | Utility-reported |
| Hillcrest | 36.9 | 2.2 | Soft | Utility-reported |
| La Cresta | 36.9 | 2.2 | Soft | Utility-reported |
| Old Stine | 36.9 | 2.2 | Soft | Utility-reported |
| Potomac Park | 36.9 | 2.2 | Soft | Utility-reported |
| Rexland Acres | 36.9 | 2.2 | Soft | Utility-reported |
| Yucaipa | 107.5 | 6.3 | Moderately hard | Utility-reported |
| Lucas Valley-Marinwood | 62.9 | 3.7 | Moderately hard | Utility-reported |
| Novato | 62.9 | 3.7 | Moderately hard | Utility-reported |
| Rose Hills | 33.7 | 2.0 | Soft | Utility-reported |
| South El Monte | 33.7 | 2.0 | Soft | Utility-reported |
| East Pasadena | 191.7 | 11.2 | Very hard | Utility-reported |
| La Riviera | 84.9 | 5.0 | Moderately hard | Utility-reported |
| Newhall | 236.0 | 13.8 | Very hard | Utility-reported |
| Wildomar | 111.0 | 6.5 | Moderately hard | Utility-reported |
| Dana Point | 145.6 | 8.5 | Hard | Utility-reported |
| Oakley | 89.3 | 5.2 | Moderately hard | Utility-reported |
| Foothill Farms | 91.6 | 5.4 | Moderately hard | Utility-reported |
| Lake Elsinore | 111.0 | 6.5 | Moderately hard | Utility-reported |
| Lakeland Village | 111.0 | 6.5 | Moderately hard | Utility-reported |
| Meadowbrook | 111.0 | 6.5 | Moderately hard | Utility-reported |
| Warm Springs | 111.0 | 6.5 | Moderately hard | Utility-reported |
| Corona | 153.9 | 9.0 | Hard | Utility-reported |
| Coronita | 153.9 | 9.0 | Hard | Utility-reported |
| Glendale | 86.4 | 5.0 | Moderately hard | Utility-reported |
| Salida | 44.5 | 2.6 | Soft | Utility-reported |
| South San Jose Hills | 208.1 | 12.2 | Very hard | Utility-reported |
| Port Hueneme | 278.0 | 16.3 | Very hard | Utility-reported |
| Sunnyvale | 298.0 | 17.4 | Very hard | Utility-reported |
| Irwindale | 123.7 | 7.2 | Hard | Utility-reported |
| Aliso Viejo | 159.7 | 9.3 | Hard | Utility-reported |
| Laguna Hills | 159.7 | 9.3 | Hard | Utility-reported |
| Lancaster | 80.2 | 4.7 | Moderately hard | Utility-reported |
| Quartz Hill | 226.0 | 13.2 | Very hard | Utility-reported |
| Fairfax | 55.8 | 3.3 | Soft | Utility-reported |
| Jamul | 289.0 | 16.9 | Very hard | Utility-reported |
| Alhambra Valley | 83.8 | 4.9 | Moderately hard | Utility-reported |
| Martinez | 83.8 | 4.9 | Moderately hard | Utility-reported |
| Vine Hill | 83.8 | 4.9 | Moderately hard | Utility-reported |
| Harmony Grove | 156.6 | 9.2 | Hard | Utility-reported |
| Vineyard | 53.1 | 3.1 | Soft | Utility-reported |
| Bay Point | 88.5 | 5.2 | Moderately hard | Utility-reported |
| Modesto | 44.5 | 2.6 | Soft | Utility-reported |
| Riverdale Park | 44.5 | 2.6 | Soft | Utility-reported |
| San Pasqual | 204.9 | 12.0 | Very hard | Utility-reported |
| Airport | 44.5 | 2.6 | Soft | Utility-reported |
| Empire | 44.5 | 2.6 | Soft | Utility-reported |
| Rouse | 44.5 | 2.6 | Soft | Utility-reported |
| West Modesto | 44.5 | 2.6 | Soft | Utility-reported |
| Bret Harte | 44.5 | 2.6 | Soft | Utility-reported |
| Bystrom | 44.5 | 2.6 | Soft | Utility-reported |
| Parklawn | 44.5 | 2.6 | Soft | Utility-reported |
| San Clemente | 168.0 | 9.8 | Hard | Utility-reported |
| La Cañada Flintridge | 218.3 | 12.8 | Very hard | Utility-reported |
| Eastvale | 113.8 | 6.7 | Moderately hard | Utility-reported |
| Highland | 123.1 | 7.2 | Hard | Utility-reported |
| Arden-Arcade | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Loma Linda | 98.7 | 5.8 | Moderately hard | Utility-reported |
| Sausalito | 55.8 | 3.3 | Soft | Utility-reported |
| Oak Glen | 136.0 | 8.0 | Hard | Utility-reported |
| Channel Islands Beach | 278.0 | 16.3 | Very hard | Utility-reported |
| El Rio | 278.0 | 16.3 | Very hard | Utility-reported |
| Oxnard | 278.0 | 16.3 | Very hard | Utility-reported |
| Desert View Highlands | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Leona Valley | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Redondo Beach | 198.0 | 11.6 | Very hard | Utility-reported |
| Oceanside | 172.2 | 10.1 | Hard | Utility-reported |
| Altadena | 233.9 | 13.7 | Very hard | Utility-reported |
| Covina | 167.2 | 9.8 | Hard | Utility-reported |
| Huntington Beach | 128.1 | 7.5 | Hard | Utility-reported |
| Clayton | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Brentwood | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Concord | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Knightsen | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Bethel Island | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Byron | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Clyde | 86.5 | 5.1 | Moderately hard | Utility-reported |
| North Gate | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Pacheco | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Redlands | 110.9 | 6.5 | Moderately hard | Utility-reported |
| McClellan Park | 97.8 | 5.7 | Moderately hard | Utility-reported |
| North Highlands | 97.8 | 5.7 | Moderately hard | Utility-reported |
| Alto | 55.8 | 3.3 | Soft | Utility-reported |
| Belvedere | 55.8 | 3.3 | Soft | Utility-reported |
| Corte Madera | 55.8 | 3.3 | Soft | Utility-reported |
| Kentfield | 55.8 | 3.3 | Soft | Utility-reported |
| Lagunitas-Forest Knolls | 55.8 | 3.3 | Soft | Utility-reported |
| Larkspur | 55.8 | 3.3 | Soft | Utility-reported |
| Marin City | 55.8 | 3.3 | Soft | Utility-reported |
| Mill Valley | 55.8 | 3.3 | Soft | Utility-reported |
| Ross | 55.8 | 3.3 | Soft | Utility-reported |
| San Anselmo | 55.8 | 3.3 | Soft | Utility-reported |
| San Geronimo | 55.8 | 3.3 | Soft | Utility-reported |
| San Rafael | 55.8 | 3.3 | Soft | Utility-reported |
| Santa Venetia | 55.8 | 3.3 | Soft | Utility-reported |
| Sleepy Hollow | 55.8 | 3.3 | Soft | Utility-reported |
| Strawberry | 55.8 | 3.3 | Soft | Utility-reported |
| Tamalpais-Homestead Valley | 55.8 | 3.3 | Soft | Utility-reported |
| Tiburon | 55.8 | 3.3 | Soft | Utility-reported |
| Woodacre | 55.8 | 3.3 | Soft | Utility-reported |
| South Whittier | 173.9 | 10.2 | Hard | Utility-reported |
| National City | 128.0 | 7.5 | Hard | Utility-reported |
| Mentone | 110.9 | 6.5 | Moderately hard | Utility-reported |
| Azusa | 116.1 | 6.8 | Moderately hard | Utility-reported |
| Alhambra | 136.7 | 8.0 | Hard | Utility-reported |
| French Camp | 10.2 | 0.6 | Soft | Computed from Ca+Mg |
| Santa Barbara | 254.7 | 14.9 | Very hard | Utility-reported |
| Santa Rosa | 120.9 | 7.1 | Hard | Utility-reported |
| La Palma | 177.4 | 10.4 | Hard | Utility-reported |
| Rancho Santa Margarita | 157.4 | 9.2 | Hard | Utility-reported |
| Thousand Oaks | 116.8 | 6.8 | Moderately hard | Utility-reported |
| Elk Grove | 49.5 | 2.9 | Soft | Utility-reported |
| Grand Terrace | 137.1 | 8.0 | Hard | Utility-reported |
| Garden Grove | 283.0 | 16.6 | Very hard | Utility-reported |
| Pasadena | 230.2 | 13.5 | Very hard | Utility-reported |
| Artesia | 125.5 | 7.3 | Hard | Utility-reported |
| Broadmoor | 73.1 | 4.3 | Moderately hard | Utility-reported |
| Colma | 73.1 | 4.3 | Moderately hard | Utility-reported |
| Daly City | 73.1 | 4.3 | Moderately hard | Utility-reported |
| San Mateo | 35.4 | 2.1 | Soft | Utility-reported |
| Laguna Niguel | 151.0 | 8.8 | Hard | Utility-reported |
| Valinda | 223.0 | 13.0 | Very hard | Utility-reported |
| Rancho Cordova | 27.8 | 1.6 | Soft | Utility-reported |
| Glendora | 122.3 | 7.2 | Hard | Utility-reported |
| La Mirada | 173.9 | 10.2 | Hard | Utility-reported |
| Coto de Caza | 158.0 | 9.2 | Hard | Utility-reported |
| Ladera Ranch | 158.0 | 9.2 | Hard | Utility-reported |
| Las Flores | 158.0 | 9.2 | Hard | Utility-reported |
| Rancho Mission Viejo | 158.0 | 9.2 | Hard | Utility-reported |
| East Los Angeles | 122.7 | 7.2 | Hard | Utility-reported |
| Rowland Heights | 160.4 | 9.4 | Hard | Utility-reported |
| Olde Stockdale | 27.4 | 1.6 | Soft | Utility-reported |
| Norwalk | 135.5 | 7.9 | Hard | Utility-reported |
| San Carlos | 32.6 | 1.9 | Soft | Utility-reported |
| Chino | 159.7 | 9.3 | Hard | Utility-reported |
| Orangevale | 45.4 | 2.6 | Soft | Utility-reported |
| Pacifica | 70.1 | 4.1 | Moderately hard | Utility-reported |
| Visalia | 74.4 | 4.3 | Moderately hard | Utility-reported |
| Santa Maria | 216.9 | 12.7 | Very hard | Utility-reported |
| Victorville | 17.4 | 1.0 | Soft | Utility-reported |
| Salinas | 106.0 | 6.2 | Moderately hard | Utility-reported |
| San Gabriel | 116.4 | 6.8 | Moderately hard | Utility-reported |
| Fullerton | 175.0 | 10.2 | Hard | Utility-reported |
| Shingle Springs | 14.3 | 0.8 | Soft | Utility-reported |
| Placerville | 14.3 | 0.8 | Soft | Utility-reported |
| Lincoln | 14.7 | 0.9 | Soft | Utility-reported |
| Coloma | 14.3 | 0.8 | Soft | Utility-reported |
| Simi Valley | 181.0 | 10.6 | Very hard | Utility-reported |
| Hidden Meadows | 181.4 | 10.6 | Very hard | Utility-reported |
| Fairfield | 109.0 | 6.4 | Moderately hard | Utility-reported |
| Desert Edge | 213.0 | 12.5 | Very hard | Utility-reported |
| Desert Hot Springs | 213.0 | 12.5 | Very hard | Utility-reported |
| Garnet | 213.0 | 12.5 | Very hard | Utility-reported |
| Placentia | 96.9 | 5.7 | Moderately hard | Computed from Ca+Mg |
| Seaside | 159.7 | 9.3 | Hard | Utility-reported |
| Vista | 213.0 | 12.5 | Very hard | Utility-reported |
| Whitewater | 213.0 | 12.5 | Very hard | Utility-reported |
| El Dorado Hills | 14.3 | 0.8 | Soft | Utility-reported |
| Santa Clara | 248.0 | 14.5 | Very hard | Utility-reported |
| Belmont | 36.9 | 2.2 | Soft | Utility-reported |
| Cameron Park | 14.3 | 0.8 | Soft | Utility-reported |
| Camino | 14.3 | 0.8 | Soft | Utility-reported |
| Cold Springs | 14.3 | 0.8 | Soft | Utility-reported |
| Diamond Springs | 14.3 | 0.8 | Soft | Utility-reported |
| Pollock Pines | 14.3 | 0.8 | Soft | Utility-reported |
| Downey | 246.6 | 14.4 | Very hard | Utility-reported |
| Del Rey Oaks | 159.7 | 9.3 | Hard | Utility-reported |
| Monterey | 159.7 | 9.3 | Hard | Utility-reported |
| La Habra | 168.5 | 9.8 | Hard | Utility-reported |
| Vallejo | 81.5 | 4.8 | Moderately hard | Utility-reported |
| Capitola | 131.6 | 7.7 | Hard | Utility-reported |
| Pleasure Point | 131.6 | 7.7 | Hard | Utility-reported |
| Soquel | 131.6 | 7.7 | Hard | Utility-reported |
| Homestead Valley | 108.7 | 6.4 | Moderately hard | Utility-reported |
| Encinitas | 156.7 | 9.2 | Hard | Utility-reported |
| Bellflower | 119.0 | 7.0 | Moderately hard | Utility-reported |
| Eucalyptus Hills | 193.5 | 11.3 | Very hard | Utility-reported |
| Clovis | 58.8 | 3.4 | Soft | Utility-reported |
| Tarpey Village | 58.8 | 3.4 | Soft | Utility-reported |
| Mountain View Acres | 16.0 | 0.9 | Soft | Utility-reported |
| San Buenaventura (Ventura) | 476.8 | 27.9 | Very hard | Utility-reported |
| Emerald Lake Hills | 32.3 | 1.9 | Soft | Utility-reported |
| Redwood City | 32.3 | 1.9 | Soft | Utility-reported |
| Yucca Valley | 109.9 | 6.4 | Moderately hard | Utility-reported |
| East Whittier | 173.9 | 10.2 | Hard | Utility-reported |
| University of California-Davis | 212.0 | 12.4 | Very hard | Utility-reported |
| Granite Bay | 13.4 | 0.8 | Soft | Utility-reported |
| Castaic | 236.0 | 13.8 | Very hard | Utility-reported |
| Huntington Park | 171.0 | 10.0 | Hard | County estimate |
| South Lake Tahoe | 45.3 | 2.6 | Soft | Computed from Ca+Mg |
| Citrus | 112.0 | 6.5 | Moderately hard | Utility-reported |
| Newcastle | 11.1 | 0.7 | Soft | Utility-reported |
| Hillsborough | 36.4 | 2.1 | Soft | Utility-reported |
| Durham | 154.0 | 9.0 | Hard | Utility-reported |
| Saticoy | 505.0 | 29.5 | Very hard | Utility-reported |
| Lakewood | 177.0 | 10.3 | Hard | Utility-reported |
| Cypress | 196.0 | 11.5 | Very hard | Utility-reported |
| Los Alamitos | 196.0 | 11.5 | Very hard | Utility-reported |
| Rossmoor | 196.0 | 11.5 | Very hard | Utility-reported |
| Stanton | 196.0 | 11.5 | Very hard | Utility-reported |
| Boronda | 106.0 | 6.2 | Moderately hard | Utility-reported |
| Calimesa | 127.4 | 7.5 | Hard | Utility-reported |
| Chico | 153.8 | 9.0 | Hard | Utility-reported |
| Redding | 31.5 | 1.8 | Soft | Utility-reported |
| Hamilton City | 154.0 | 9.0 | Hard | Utility-reported |
| Hesperia | 108.0 | 6.3 | Moderately hard | Utility-reported |
| Stevenson Ranch | 236.0 | 13.8 | Very hard | Utility-reported |
| Vincent | 112.0 | 6.5 | Moderately hard | Utility-reported |
| Temple City | 112.7 | 6.6 | Moderately hard | Utility-reported |
| Meyers | 45.7 | 2.7 | Soft | Computed from Ca+Mg |
| Lake San Marcos | 170.0 | 9.9 | Hard | Utility-reported |
| Fairbanks Ranch | 142.9 | 8.4 | Hard | Utility-reported |
| Rancho Santa Fe | 142.9 | 8.4 | Hard | Utility-reported |
| Solana Beach | 142.9 | 8.4 | Hard | Utility-reported |
| Montecito | 220.0 | 12.9 | Very hard | Utility-reported |
| Imperial Beach | 200.0 | 11.7 | Very hard | Utility-reported |
| Vacaville | 94.1 | 5.5 | Moderately hard | Utility-reported |
| Folsom | 18.1 | 1.1 | Soft | Utility-reported |
| Baywood Park | 37.6 | 2.2 | Soft | Utility-reported |
| Highlands | 37.6 | 2.2 | Soft | Utility-reported |
| Fair Oaks | 52.6 | 3.1 | Soft | Utility-reported |
| Cherry Valley | 127.4 | 7.5 | Hard | Utility-reported |
| Shasta Lake | 29.8 | 1.7 | Soft | Utility-reported |
| Alpine | 209.0 | 12.2 | Very hard | Utility-reported |
| Stanford | 146.0 | 8.5 | Hard | Utility-reported |
| Diamond Bar | 153.0 | 8.9 | Hard | Utility-reported |
| Midway City | 267.0 | 15.6 | Very hard | County estimate |
| Tracy | 67.2 | 3.9 | Moderately hard | Utility-reported |
| Elmira | 93.8 | 5.5 | Moderately hard | Utility-reported |
| Hermosa Beach | 198.0 | 11.6 | Very hard | Utility-reported |
| Livermore | 94.4 | 5.5 | Moderately hard | Utility-reported |
| Mission Canyon | 220.0 | 12.9 | Very hard | Utility-reported |
| Westminster | 267.0 | 15.6 | Very hard | County estimate |
| Santa Susana | 161.0 | 9.4 | Hard | Utility-reported |
| Pacific Grove | 169.1 | 9.9 | Hard | Utility-reported |
| Dublin | 194.9 | 11.4 | Very hard | Utility-reported |
| Merced | 137.5 | 8.0 | Hard | County estimate |
| Santa Monica | 57.4 | 3.4 | Soft | Utility-reported |
| Agoura Hills | 88.5 | 5.2 | Moderately hard | Utility-reported |
| Westlake Village | 88.5 | 5.2 | Moderately hard | Utility-reported |
| Centerville | 29.8 | 1.7 | Soft | Utility-reported |
| Carmel-by-the-Sea | 167.0 | 9.8 | Hard | Utility-reported |
| Carmel Valley Village | 167.0 | 9.8 | Hard | Utility-reported |
| Del Monte Forest | 167.0 | 9.8 | Hard | Utility-reported |
| Sand City | 167.0 | 9.8 | Hard | Utility-reported |
| Lynwood | 171.0 | 10.0 | Hard | County estimate |
| Harbison Canyon | 209.0 | 12.2 | Very hard | Utility-reported |
| Apple Valley | 205.0 | 12.0 | Very hard | Utility-reported |
| Charter Oak | 275.0 | 16.1 | Very hard | Utility-reported |
| Napa | 54.3 | 3.2 | Soft | Utility-reported |
| Eastern Goleta Valley | 291.9 | 17.1 | Very hard | Utility-reported |
| Loomis | 11.3 | 0.7 | Soft | Utility-reported |
| Woodside | 32.2 | 1.9 | Soft | Utility-reported |
| Mayflower Village | 135.3 | 7.9 | Hard | Utility-reported |
| North Fair Oaks | 32.2 | 1.9 | Soft | Utility-reported |
| Penryn | 11.3 | 0.7 | Soft | Utility-reported |
| Rocklin | 11.3 | 0.7 | Soft | Utility-reported |
| La Verne | 230.6 | 13.5 | Very hard | Utility-reported |
| Santa Cruz | 147.0 | 8.6 | Hard | Utility-reported |
| Live Oak | 147.0 | 8.6 | Hard | Utility-reported |
| Pasatiempo | 147.0 | 8.6 | Hard | Utility-reported |
| Twin Lakes | 147.0 | 8.6 | Hard | Utility-reported |
| Silverado Resort | 54.4 | 3.2 | Soft | Utility-reported |
| Elfin Forest | 129.0 | 7.5 | Hard | Utility-reported |
| Manteca | 75.3 | 4.4 | Moderately hard | Utility-reported |
| Goleta | 294.0 | 17.2 | Very hard | Utility-reported |
| Isla Vista | 294.0 | 17.2 | Very hard | Utility-reported |
| University of California-Santa Barbara | 294.0 | 17.2 | Very hard | Utility-reported |
| South Gate | 217.0 | 12.7 | Very hard | Utility-reported |
| Yorba Linda | 48.2 | 2.8 | Soft | Computed from Ca+Mg |
| Chino Hills | 81.4 | 4.8 | Moderately hard | Utility-reported |
| San Antonio Heights | 126.0 | 7.4 | Hard | Utility-reported |
| Buena Park | 154.0 | 9.0 | Hard | Utility-reported |
| Lake Mathews | 140.0 | 8.2 | Hard | Utility-reported |
| Sunol | 161.0 | 9.4 | Hard | Utility-reported |
| Pleasanton | 161.0 | 9.4 | Hard | Utility-reported |
| Upland | 126.0 | 7.4 | Hard | Utility-reported |
| Milpitas | 49.1 | 2.9 | Soft | Utility-reported |
| Los Altos Hills | 274.4 | 16.1 | Very hard | Utility-reported |
| South San Francisco | 64.5 | 3.8 | Moderately hard | Utility-reported |
| North Tustin | 243.0 | 14.2 | Very hard | Utility-reported |
| Yuba City | 247.0 | 14.4 | Very hard | County estimate |
| Turlock | 98.3 | 5.8 | Moderately hard | Utility-reported |
| San Marino | 116.4 | 6.8 | Moderately hard | Utility-reported |
| Calabasas | 76.6 | 4.5 | Moderately hard | Utility-reported |
| Hidden Hills | 76.6 | 4.5 | Moderately hard | Utility-reported |
| Pepperdine University | 76.6 | 4.5 | Moderately hard | Utility-reported |
| Topanga | 76.6 | 4.5 | Moderately hard | Utility-reported |
| Davis | 68.3 | 4.0 | Moderately hard | Utility-reported |
| El Macero | 68.3 | 4.0 | Moderately hard | Utility-reported |
| Claremont | 156.8 | 9.2 | Hard | Utility-reported |
| North El Monte | 165.0 | 9.7 | Hard | Utility-reported |
| Tulare | 37.0 | 2.2 | Soft | Utility-reported |
| Rancho Palos Verdes | 171.0 | 10.0 | Hard | County estimate |
| Los Altos | 298.0 | 17.4 | Very hard | Utility-reported |
| Loyola | 298.0 | 17.4 | Very hard | Utility-reported |
| San Bruno | 43.8 | 2.6 | Soft | Utility-reported |
| Lodi | 4.3 | 0.3 | Soft | Computed from Ca+Mg |
| Palo Alto | 29.3 | 1.7 | Soft | Utility-reported |
| Parkwood | 133.0 | 7.8 | Hard | Utility-reported |
| Day Valley | 214.1 | 12.5 | Very hard | Utility-reported |
| Porterville | 233.0 | 13.6 | Very hard | Utility-reported |
| Madera | 94.0 | 5.5 | Moderately hard | County estimate |
| Casa Conejo | 111.0 | 6.5 | Moderately hard | Utility-reported |
| Bell Gardens | 171.0 | 10.0 | Hard | County estimate |
| Watsonville | 215.0 | 12.6 | Very hard | Utility-reported |
| Freedom | 215.0 | 12.6 | Very hard | Utility-reported |
| Amesti | 215.0 | 12.6 | Very hard | Utility-reported |
| Aptos Hills-Larkin Valley | 215.0 | 12.6 | Very hard | Utility-reported |
| Corralitos | 215.0 | 12.6 | Very hard | Utility-reported |
| Interlaken | 215.0 | 12.6 | Very hard | Utility-reported |
| Parkway | 66.1 | 3.9 | Moderately hard | Utility-reported |
| Petaluma | 105.0 | 6.1 | Moderately hard | Utility-reported |
| Paramount | 108.0 | 6.3 | Moderately hard | Utility-reported |
| Woodland | 43.7 | 2.6 | Soft | Utility-reported |
| Monrovia | 135.3 | 7.9 | Hard | Utility-reported |
| Hanford | 11.0 | 0.6 | Soft | Utility-reported |
| Black Point-Green Point | 85.2 | 5.0 | Moderately hard | Utility-reported |
| Inverness | 85.2 | 5.0 | Moderately hard | Utility-reported |
| Point Reyes Station | 85.2 | 5.0 | Moderately hard | Utility-reported |
| Shafter | 181.0 | 10.6 | Very hard | County estimate |
| Gilroy | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Fallbrook | 118.7 | 6.9 | Moderately hard | Utility-reported |
| Camp Pendleton Mainside | 117.0 | 6.8 | Moderately hard | Utility-reported |
| Camp Pendleton South | 117.0 | 6.8 | Moderately hard | Utility-reported |
| Montclair | 166.0 | 9.7 | Hard | Utility-reported |
| Fountain Valley | 125.0 | 7.3 | Hard | Utility-reported |
| Delano | 181.0 | 10.6 | Very hard | County estimate |
| San Dimas | 275.0 | 16.1 | Very hard | Utility-reported |
| Mather | 38.4 | 2.3 | Soft | Utility-reported |
| Rosemont | 38.4 | 2.3 | Soft | Utility-reported |
| West Sacramento | 35.0 | 2.0 | Soft | Utility-reported |
| South Monrovia Island | 74.8 | 4.4 | Moderately hard | Utility-reported |
| Cotati | 106.0 | 6.2 | Moderately hard | Utility-reported |
| Florin | 66.1 | 3.9 | Moderately hard | Utility-reported |
| Cerritos | 135.0 | 7.9 | Hard | Utility-reported |
| Elverta | 82.8 | 4.8 | Moderately hard | Utility-reported |
| Poway | 194.0 | 11.3 | Very hard | Utility-reported |
| Menlo Park | 45.7 | 2.7 | Soft | Utility-reported |
| Olivehurst | 148.5 | 8.7 | Hard | County estimate |
| Cutten | 77.9 | 4.6 | Moderately hard | Utility-reported |
| Myrtletown | 77.9 | 4.6 | Moderately hard | Utility-reported |
| Gold River | 30.0 | 1.8 | Soft | Computed from Ca+Mg |
| Suisun City | 107.0 | 6.3 | Moderately hard | Utility-reported |
| El Centro | 150.0 | 8.8 | Hard | County estimate |
| Brea | 191.0 | 11.2 | Very hard | Utility-reported |
| Oroville | 24.1 | 1.4 | Soft | Utility-reported |
| Rohnert Park | 106.0 | 6.2 | Moderately hard | Utility-reported |
| Sonoma State University | 106.0 | 6.2 | Moderately hard | Utility-reported |
| La Crescenta-Montrose | 3.3 | 0.2 | Soft | Utility-reported |
| Aptos | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Big Bear City | 160.7 | 9.4 | Hard | Utility-reported |
| Seacliff | 98.4 | 5.8 | Moderately hard | Utility-reported |
| La Selva Beach | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Rio del Mar | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Calexico | 174.0 | 10.2 | Hard | Utility-reported |
| Barstow | 79.5 | 4.7 | Moderately hard | Utility-reported |
| Marina | 142.0 | 8.3 | Hard | Utility-reported |
| Moorpark | 190.0 | 11.1 | Very hard | Utility-reported |
| Foster City | 33.0 | 1.9 | Soft | Utility-reported |
| Sonoma | 83.6 | 4.9 | Moderately hard | Utility-reported |
| Manhattan Beach | 215.0 | 12.6 | Very hard | Utility-reported |
| Ramona | 84.9 | 5.0 | Moderately hard | Utility-reported |
| East Palo Alto | 77.4 | 4.5 | Moderately hard | Utility-reported |
| San Diego Country Estates | 84.9 | 5.0 | Moderately hard | Utility-reported |
| Orcutt | 233.0 | 13.6 | Very hard | Utility-reported |
| South Oroville | 24.1 | 1.4 | Soft | Utility-reported |
| Oak Park | 137.6 | 8.1 | Hard | Utility-reported |
| Scotts Valley | 148.0 | 8.7 | Hard | Utility-reported |
| North Auburn | 11.7 | 0.7 | Soft | Utility-reported |
| Lathrop | 57.6 | 3.4 | Soft | Utility-reported |
| Camarillo | 217.5 | 12.7 | Very hard | Utility-reported |
| Santa Rosa Valley | 52.0 | 3.0 | Soft | Utility-reported |
| La Crescenta | 171.0 | 10.0 | Hard | County estimate |
| Banning | 186.0 | 10.9 | Very hard | County estimate |
| Burlingame | 30.9 | 1.8 | Soft | Utility-reported |
| Adelanto | 111.0 | 6.5 | Moderately hard | County estimate |
| Atwater | 137.5 | 8.0 | Hard | County estimate |
| Benicia | 56.5 | 3.3 | Soft | Utility-reported |
| Atascadero | 39.0 | 2.3 | Soft | Computed from Ca+Mg |
| Valley Center | 223.0 | 13.0 | Very hard | Utility-reported |
| Big Bear Lake | 173.2 | 10.1 | Hard | Utility-reported |
| Wasco | 181.0 | 10.6 | Very hard | County estimate |
| Windsor | 120.0 | 7.0 | Moderately hard | County estimate |
| Auburn | 10.8 | 0.6 | Soft | Utility-reported |
| Lucerne Valley | 52.6 | 3.1 | Soft | Utility-reported |
| Eureka | 77.9 | 4.6 | Moderately hard | Utility-reported |
| Phelan | 111.0 | 6.5 | Moderately hard | County estimate |
| Plumas Lake | 197.0 | 11.5 | Very hard | Utility-reported |
| Brawley | 150.0 | 8.8 | Hard | County estimate |
| Dinuba | 91.5 | 5.3 | Moderately hard | Utility-reported |
| Felton | 140.2 | 8.2 | Hard | Utility-reported |
| Camp Pendleton | 125.0 | 7.3 | Hard | Utility-reported |
| Selma | 202.0 | 11.8 | Very hard | County estimate |
| Lemoore | 25.6 | 1.5 | Soft | Utility-reported |
| Ukiah | 55.0 | 3.2 | Soft | Utility-reported |
| Reedley | 202.0 | 11.8 | Very hard | County estimate |
| Del Mar | 199.0 | 11.6 | Very hard | Utility-reported |
| Riverbank | 195.9 | 11.5 | Very hard | Utility-reported |
| Soledad | 227.0 | 13.3 | Very hard | County estimate |
| Ben Lomond | 143.6 | 8.4 | Hard | Utility-reported |
| South Pasadena | 128.0 | 7.5 | Hard | Utility-reported |
| Bradbury | 74.8 | 4.4 | Moderately hard | Utility-reported |
| Duarte | 74.8 | 4.4 | Moderately hard | Utility-reported |
| Seal Beach | 169.0 | 9.9 | Hard | Utility-reported |
| Oakdale | 94.1 | 5.5 | Moderately hard | Utility-reported |
| Moss Beach | 60.6 | 3.5 | Moderately hard | Utility-reported |
| Ojai | 228.4 | 13.4 | Very hard | Utility-reported |
| Patterson | 471.0 | 27.5 | Very hard | County estimate |
| Bonsall | 196.0 | 11.5 | Very hard | Utility-reported |
| Rainbow | 196.0 | 11.5 | Very hard | Utility-reported |
| El Verano | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Mountain House | 60.6 | 3.5 | Moderately hard | Utility-reported |
| Boyes Hot Springs | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Eldridge | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Fetters Hot Springs-Agua Caliente | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Glen Ellen | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Temelec | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Millbrae | 43.8 | 2.6 | Soft | Utility-reported |
| Boulder Creek | 147.9 | 8.7 | Hard | Utility-reported |
| Palermo | 111.0 | 6.5 | Moderately hard | County estimate |
| Dixon | 152.0 | 8.9 | Hard | Utility-reported |
| Maricopa | 400.0 | 23.4 | Very hard | County estimate |
| Taft | 181.0 | 10.6 | Very hard | County estimate |
| Grass Valley | 12.6 | 0.7 | Soft | Utility-reported |
| Meiners Oaks | 227.7 | 13.3 | Very hard | Utility-reported |
| Corcoran | 64.3 | 3.8 | Moderately hard | County estimate |
| Zayante | 149.0 | 8.7 | Hard | Utility-reported |
| Maywood | 171.0 | 10.0 | Hard | County estimate |
| Lake Sherwood | 133.0 | 7.8 | Hard | Utility-reported |
| Arcata | 155.0 | 9.1 | Hard | County estimate |
| Brookdale | 149.0 | 8.7 | Hard | Utility-reported |
| Lompico | 149.0 | 8.7 | Hard | Utility-reported |
| American Canyon | 64.6 | 3.8 | Moderately hard | Utility-reported |
| Mira Monte | 196.8 | 11.5 | Very hard | Utility-reported |
| Nevada City | 11.1 | 0.7 | Soft | Utility-reported |
| Clearlake | 95.6 | 5.6 | Moderately hard | Utility-reported |
| Imperial | 94.4 | 5.5 | Moderately hard | Utility-reported |
| Arvin | 181.0 | 10.6 | Very hard | County estimate |
| McKinleyville | 91.0 | 5.3 | Moderately hard | Utility-reported |
| Lamont | 181.0 | 10.6 | Very hard | County estimate |
| Arroyo Grande | 310.1 | 18.1 | Very hard | Utility-reported |
| Blythe | 186.0 | 10.9 | Very hard | County estimate |
| Twentynine Palms | 111.0 | 6.5 | Moderately hard | County estimate |
| El Granada | 45.8 | 2.7 | Soft | Utility-reported |
| Half Moon Bay | 45.8 | 2.7 | Soft | Utility-reported |
| Bella Vista | 39.4 | 2.3 | Soft | Utility-reported |
| Palo Cedro | 39.4 | 2.3 | Soft | Utility-reported |
| Nipomo | 604.0 | 35.3 | Very hard | Utility-reported |
| Coalinga | 118.0 | 6.9 | Moderately hard | Utility-reported |
| Crescent City | 87.7 | 5.1 | Moderately hard | County estimate |
| Rosamond | 103.0 | 6.0 | Moderately hard | Utility-reported |
| Crestline | 51.3 | 3.0 | Soft | Utility-reported |
| Sonora | 35.8 | 2.1 | Soft | Utility-reported |
| Rough and Ready | 12.5 | 0.7 | Soft | Utility-reported |
| Fillmore | 76.6 | 4.5 | Moderately hard | Utility-reported |
| El Segundo | 172.0 | 10.1 | Hard | Utility-reported |
| Discovery Bay | 137.0 | 8.0 | Hard | Utility-reported |
| Sunnyside | 167.0 | 9.8 | Hard | Utility-reported |
| Fort Dick | 87.7 | 5.1 | Moderately hard | County estimate |
| Oak View | 186.0 | 10.9 | Very hard | Utility-reported |
| Ripon | 27.8 | 1.6 | Soft | Utility-reported |
| Jamestown | 39.6 | 2.3 | Soft | Utility-reported |
| Fort Irwin | 23.8 | 1.4 | Soft | Utility-reported |
| Carpinteria | 519.0 | 30.4 | Very hard | County estimate |
| Morro Bay | 148.9 | 8.7 | Hard | Utility-reported |
| Los Berros | 604.0 | 35.3 | Very hard | Utility-reported |
| Chowchilla | 94.0 | 5.5 | Moderately hard | County estimate |
| McFarland | 5.0 | 0.3 | Soft | Utility-reported |
| Kerman | 202.0 | 11.8 | Very hard | County estimate |
| Tehachapi | 363.0 | 21.2 | Very hard | Utility-reported |
| California City | 73.3 | 4.3 | Moderately hard | Utility-reported |
| Livingston | 137.5 | 8.0 | Hard | County estimate |
| Red Bluff | 113.0 | 6.6 | Moderately hard | County estimate |
| Pala | 366.0 | 21.4 | Very hard | County estimate |
| Cutler | 170.0 | 9.9 | Hard | Utility-reported |
| Orosi | 170.0 | 9.9 | Hard | Utility-reported |
| Parlier | 202.0 | 11.8 | Very hard | County estimate |
| Rio Linda | 93.4 | 5.5 | Moderately hard | Utility-reported |
| Alta Sierra | 15.5 | 0.9 | Soft | Utility-reported |
| Lemoore Station | 99.7 | 5.8 | Moderately hard | Utility-reported |
| Lake Arrowhead | 55.8 | 3.3 | Soft | Utility-reported |
| Avenal | 64.3 | 3.8 | Moderately hard | County estimate |
| Trabuco Canyon | 150.0 | 8.8 | Hard | Utility-reported |
| Los Osos | 38.5 | 2.3 | Soft | Computed from Ca+Mg |
| Lindsay | 303.0 | 17.7 | Very hard | Utility-reported |
| Healdsburg | 93.3 | 5.5 | Moderately hard | Utility-reported |
| Grover Beach | 470.0 | 27.5 | Very hard | County estimate |
| Marysville | 97.8 | 5.7 | Moderately hard | Utility-reported |
| Lake Los Angeles | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Fortuna | 155.0 | 9.1 | Hard | County estimate |
| Edwards AFB | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Anderson | 97.7 | 5.7 | Moderately hard | Utility-reported |
| Kingsburg | 91.3 | 5.3 | Moderately hard | Utility-reported |
| Summerland | 519.0 | 30.4 | Very hard | County estimate |
| Newman | 471.0 | 27.5 | Very hard | County estimate |
| Exeter | 4.5 | 0.3 | Soft | County estimate |
| East Sonora | 44.1 | 2.6 | Soft | Utility-reported |
| Valley Springs | 51.6 | 3.0 | Soft | Utility-reported |
| Greenfield | 227.0 | 13.3 | Very hard | County estimate |
| Mendota | 16.8 | 1.0 | Soft | Utility-reported |
| Cloverdale | 120.0 | 7.0 | Moderately hard | County estimate |
| Needles | 111.0 | 6.5 | Moderately hard | County estimate |
| Twain Harte | 2.8 | 0.2 | Soft | County estimate |
| Sierra Madre | 161.0 | 9.4 | Hard | Utility-reported |
| Ione | 85.2 | 5.0 | Moderately hard | County estimate |
| Farmersville | 4.5 | 0.3 | Soft | County estimate |
| Rio Vista | 49.3 | 2.9 | Soft | Utility-reported |
| Carnelian Bay | 34.0 | 2.0 | Soft | County estimate |
| Waterford | 16.4 | 1.0 | Soft | Utility-reported |
| Rancho Calaveras | 54.5 | 3.2 | Soft | Utility-reported |
| Orange Cove | 4.5 | 0.3 | Soft | County estimate |
| Pine Grove | 85.2 | 5.0 | Moderately hard | County estimate |
| Winton | 137.5 | 8.0 | Hard | County estimate |
| Running Springs | 35.9 | 2.1 | Soft | Utility-reported |
| Penn Valley | 19.3 | 1.1 | Soft | Utility-reported |
| Penngrove | 120.0 | 7.0 | Moderately hard | County estimate |
| Huron | 202.0 | 11.8 | Very hard | County estimate |
| La Canada | 3.3 | 0.2 | Soft | Utility-reported |
| Georgetown | 32.8 | 1.9 | Soft | County estimate |
| Lake Wildwood | 19.3 | 1.1 | Soft | Utility-reported |
| Pioneer | 85.2 | 5.0 | Moderately hard | County estimate |
| Gonzales | 227.0 | 13.3 | Very hard | County estimate |
| Joshua Tree | 70.4 | 4.1 | Moderately hard | Utility-reported |
| Guadalupe | 519.0 | 30.4 | Very hard | County estimate |
| Avila Beach | 470.0 | 27.5 | Very hard | County estimate |
| Pismo Beach | 149.0 | 8.7 | Hard | Utility-reported |
| Tahoma | 65.0 | 3.8 | Moderately hard | Utility-reported |
| Firebaugh | 121.0 | 7.1 | Hard | Utility-reported |
| Delhi | 137.5 | 8.0 | Hard | County estimate |
| Earlimart | 4.5 | 0.3 | Soft | County estimate |
| Oceano | 470.0 | 27.5 | Very hard | County estimate |
| Sebastopol | 142.0 | 8.3 | Hard | Utility-reported |
| Escalon | 27.8 | 1.6 | Soft | Utility-reported |
| Winters | 214.5 | 12.5 | Very hard | County estimate |
| Hughson | 471.0 | 27.5 | Very hard | County estimate |
| Skyforest | 111.0 | 6.5 | Moderately hard | County estimate |
| Heber | 53.2 | 3.1 | Soft | Utility-reported |
| Foresthill | 34.0 | 2.0 | Soft | County estimate |
| San Andreas | 34.0 | 2.0 | Soft | Utility-reported |
| Madera Acres | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Spreckels | 257.0 | 15.0 | Very hard | Utility-reported |
| Mokelumne Hill | 29.2 | 1.7 | Soft | Utility-reported |
| Paloma | 29.2 | 1.7 | Soft | Utility-reported |
| Malaga | 113.5 | 6.6 | Moderately hard | Computed from Ca+Mg |
| Gustine | 137.5 | 8.0 | Hard | County estimate |
| Shasta | 73.1 | 4.3 | Moderately hard | County estimate |
| Yountville | 108.0 | 6.3 | Moderately hard | County estimate |
| Hasley Canyon | 84.4 | 4.9 | Moderately hard | Utility-reported |
| Val Verde | 84.4 | 4.9 | Moderately hard | Utility-reported |
| Keyes | 471.0 | 27.5 | Very hard | County estimate |
| Villa Park | 252.0 | 14.7 | Very hard | Utility-reported |
| Cedar Flat | 65.0 | 3.8 | Moderately hard | Utility-reported |
| Dollar Point | 65.0 | 3.8 | Moderately hard | Utility-reported |
| Sunnyside-Tahoe City | 65.0 | 3.8 | Moderately hard | Utility-reported |
| Bear Valley Springs | 158.0 | 9.2 | Hard | Utility-reported |
| Cayucos | 216.0 | 12.6 | Very hard | Utility-reported |
| Hilmar | 137.5 | 8.0 | Hard | County estimate |
| Idyllwild | 34.0 | 2.0 | Soft | Utility-reported |
| Idyllwild-Pine Cove | 34.0 | 2.0 | Soft | Utility-reported |
| Weed | 89.3 | 5.2 | Moderately hard | County estimate |
| Montara | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Redwood Valley | 102.0 | 6.0 | Moderately hard | County estimate |
| Denair | 118.0 | 6.9 | Moderately hard | Utility-reported |
| Copperopolis | 28.3 | 1.6 | Soft | Utility-reported |
| Meadow Vista | 34.0 | 2.0 | Soft | County estimate |
| Hoopa | 99.0 | 5.8 | Moderately hard | Utility-reported |
| Sutter Creek | 29.1 | 1.7 | Soft | Utility-reported |
| Amador City | 85.2 | 5.0 | Moderately hard | County estimate |
| Columbia | 9.5 | 0.6 | Soft | Utility-reported |
| Tuttletown | 9.5 | 0.6 | Soft | Utility-reported |
| Lakeport | 99.5 | 5.8 | Moderately hard | County estimate |
| Brisbane | 25.8 | 1.5 | Soft | Utility-reported |
| Represa | 66.9 | 3.9 | Moderately hard | County estimate |
| Angwin | 108.0 | 6.3 | Moderately hard | County estimate |
| Mojave | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Murphys | 101.7 | 6.0 | Moderately hard | County estimate |
| Three Rivers | 122.1 | 7.1 | Hard | Utility-reported |
| Planada | 137.5 | 8.0 | Hard | County estimate |
| Ivanhoe | 250.0 | 14.6 | Very hard | Utility-reported |
| Julian | 61.9 | 3.6 | Moderately hard | Utility-reported |
| North Lakeport | 63.7 | 3.7 | Moderately hard | Utility-reported |
| Commerce | 75.0 | 4.4 | Moderately hard | Utility-reported |
| Prunedale | 92.3 | 5.4 | Moderately hard | Utility-reported |
| Armona | 64.3 | 3.8 | Moderately hard | County estimate |
| Avalon | 171.0 | 10.0 | Hard | County estimate |
| San Joaquin | 45.0 | 2.6 | Soft | Utility-reported |
| Bishop | 84.6 | 5.0 | Moderately hard | County estimate |
| Angels | 20.7 | 1.2 | Soft | Utility-reported |
| Angels Camp | 101.7 | 6.0 | Moderately hard | County estimate |
| City Of Angels | 20.7 | 1.2 | Soft | Utility-reported |
| Wheatland | 148.5 | 8.7 | Hard | County estimate |
| Mount Shasta | 89.3 | 5.2 | Moderately hard | County estimate |
| Mt. Shasta | 89.3 | 5.2 | Moderately hard | County estimate |
| Borrego Springs | 366.0 | 21.4 | Very hard | County estimate |
| Camanche North Shore | 55.3 | 3.2 | Soft | Utility-reported |
| Groveland | 2.8 | 0.2 | Soft | County estimate |
| Oakhurst | 119.0 | 7.0 | Moderately hard | Utility-reported |
| Cobb | 99.5 | 5.8 | Moderately hard | County estimate |
| Rio Dell | 155.0 | 9.1 | Hard | County estimate |
| Forestville | 120.0 | 7.0 | Moderately hard | County estimate |
| Aromas | 227.0 | 13.3 | Very hard | County estimate |
| Burney | 73.1 | 4.3 | Moderately hard | County estimate |
| Littlerock | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Sun Village | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Brooks | 214.5 | 12.5 | Very hard | County estimate |
| Esparto | 260.0 | 15.2 | Very hard | Utility-reported |
| Green Valley Lake | 41.7 | 2.4 | Soft | Utility-reported |
| Terra Bella | 4.5 | 0.3 | Soft | County estimate |
| Bradley | 227.0 | 13.3 | Very hard | County estimate |
| Sutter | 247.0 | 14.4 | Very hard | County estimate |
| Lockeford | 98.0 | 5.7 | Moderately hard | Utility-reported |
| Mount Hermon | 210.0 | 12.3 | Very hard | County estimate |
| June Lake | 84.6 | 5.0 | Moderately hard | County estimate |
| Arbuckle | 143.4 | 8.4 | Hard | County estimate |
| Brownsville | 148.5 | 8.7 | Hard | County estimate |
| Pixley | 4.5 | 0.3 | Soft | County estimate |
| Nice | 99.5 | 5.8 | Moderately hard | County estimate |
| Alturas | 63.8 | 3.7 | Moderately hard | County estimate |
| Tipton | 4.5 | 0.3 | Soft | County estimate |
| Ferndale | 75.9 | 4.4 | Moderately hard | Utility-reported |
| Lucerne | 94.3 | 5.5 | Moderately hard | Utility-reported |
| Smith River | 87.7 | 5.1 | Moderately hard | County estimate |
| Gualala | 102.0 | 6.0 | Moderately hard | County estimate |
| Cabazon | 186.0 | 10.9 | Very hard | County estimate |
| Pine Valley | 366.0 | 21.4 | Very hard | County estimate |
| Cedarpines Park | 34.9 | 2.0 | Soft | Utility-reported |
| Willow Creek | 99.0 | 5.8 | Moderately hard | Utility-reported |
| Bolinas | 91.0 | 5.3 | Moderately hard | County estimate |
| Clearlake Oak | 106.0 | 6.2 | Moderately hard | Utility-reported |
| Clearlake Oaks | 106.0 | 6.2 | Moderately hard | Utility-reported |
| San Juan Bautista | 272.0 | 15.9 | Very hard | County estimate |
| Westmorland | 150.0 | 8.8 | Hard | County estimate |
| Chester | 68.8 | 4.0 | Moderately hard | County estimate |
| Herlong | 82.6 | 4.8 | Moderately hard | County estimate |
| Portola | 68.8 | 4.0 | Moderately hard | County estimate |
| Las Lomas | 148.0 | 8.7 | Hard | Utility-reported |
| East Oakdale | 216.3 | 12.7 | Very hard | Utility-reported |
| Pauma Valley | 346.0 | 20.2 | Very hard | Utility-reported |
| Seeley | 150.0 | 8.8 | Hard | County estimate |
| Diablo Grande | 71.0 | 4.2 | Moderately hard | Utility-reported |
| Laytonville | 102.0 | 6.0 | Moderately hard | County estimate |
| Carmel | 92.3 | 5.4 | Moderately hard | Utility-reported |
| Isleton | 28.1 | 1.6 | Soft | Utility-reported |
| Bell Canyon | 52.0 | 3.0 | Soft | Utility-reported |
| Blue Lake | 155.0 | 9.1 | Hard | County estimate |
| Trona | 111.0 | 6.5 | Moderately hard | County estimate |
| Biggs | 111.0 | 6.5 | Moderately hard | County estimate |
| Linden | 151.0 | 8.8 | Hard | County estimate |
| Tuolumne City | 11.9 | 0.7 | Soft | Utility-reported |
| Lost Hills | 60.2 | 3.5 | Moderately hard | Computed from Ca+Mg |
| Laton | 54.3 | 3.2 | Soft | Utility-reported |
| Dunsmuir | 38.8 | 2.3 | Soft | Utility-reported |
| Strathmore | 4.5 | 0.3 | Soft | County estimate |
| Westwood | 82.6 | 4.8 | Moderately hard | County estimate |
| Los Alamos | 519.0 | 30.4 | Very hard | County estimate |
| Biola | 202.0 | 11.8 | Very hard | County estimate |
| Richgrove | 4.5 | 0.3 | Soft | County estimate |
| Pine Mountain Club | 181.0 | 10.6 | Very hard | County estimate |
| Le Grand | 137.5 | 8.0 | Hard | County estimate |
| Westhaven-Moonstone | 7.7 | 0.5 | Soft | Computed from Ca+Mg |
| Fall River Mills | 73.1 | 4.3 | Moderately hard | County estimate |
| Buttonwillow | 181.0 | 10.6 | Very hard | County estimate |
| Weimar | 13.3 | 0.8 | Soft | Utility-reported |
| Montague | 89.3 | 5.2 | Moderately hard | County estimate |
| Middletown | 99.5 | 5.8 | Moderately hard | County estimate |
| Los Molinos | 113.0 | 6.6 | Moderately hard | County estimate |
| Hydesville | 155.0 | 9.1 | Hard | County estimate |
| Plymouth | 85.2 | 5.0 | Moderately hard | County estimate |
| Del Rey | 202.0 | 11.8 | Very hard | County estimate |
| Del Rio | 16.4 | 1.0 | Soft | Utility-reported |
| San Luis Obispo | 216.0 | 12.6 | Very hard | Utility-reported |
| Mccloud | 89.3 | 5.2 | Moderately hard | County estimate |
| North Edwards | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Happy Camp | 89.3 | 5.2 | Moderately hard | County estimate |
| Geyserville | 120.0 | 7.0 | Moderately hard | County estimate |
| Knights Landing | 167.0 | 9.8 | Hard | Utility-reported |
| Stratford | 64.3 | 3.8 | Moderately hard | County estimate |
| Pinecrest | 2.8 | 0.2 | Soft | County estimate |
| Upper Lake | 99.5 | 5.8 | Moderately hard | County estimate |
| Yermo | 111.0 | 6.5 | Moderately hard | County estimate |
| Big Pine | 71.3 | 4.2 | Moderately hard | County estimate |
| San Martin | 49.1 | 2.9 | Soft | Utility-reported |
| Garberville | 155.0 | 9.1 | Hard | County estimate |
| Redway | 155.0 | 9.1 | Hard | County estimate |
| Maxwell | 143.4 | 8.4 | Hard | County estimate |
| Camp Meeker | 120.0 | 7.0 | Moderately hard | County estimate |
| Kettleman City | 37.0 | 2.2 | Soft | Utility-reported |
| Phoenix Lake | 33.7 | 2.0 | Soft | Utility-reported |
| Olympic Valley | 34.0 | 2.0 | Soft | County estimate |
| Trinidad | 155.0 | 9.1 | Hard | County estimate |
| Bodega Bay | 120.0 | 7.0 | Moderately hard | County estimate |
| Platina | 127.0 | 7.4 | Hard | County estimate |
| La Grange | 2.8 | 0.2 | Soft | County estimate |
| Hume | 202.0 | 11.8 | Very hard | County estimate |
| Paicines | 272.0 | 15.9 | Very hard | County estimate |
| Baker | 111.0 | 6.5 | Moderately hard | County estimate |
| Forest Falls | 86.0 | 5.0 | Moderately hard | Utility-reported |
| Mt. Shasta | 89.3 | 5.2 | Moderately hard | County estimate |
| Sultana | 4.5 | 0.3 | Soft | County estimate |
| Westley | 471.0 | 27.5 | Very hard | County estimate |
| Loleta | 155.0 | 9.1 | Hard | County estimate |
| Scotia | 155.0 | 9.1 | Hard | County estimate |
| Tranquillity | 202.0 | 11.8 | Very hard | County estimate |
| Madison | 203.0 | 11.9 | Very hard | Utility-reported |
| Descanso | 366.0 | 21.4 | Very hard | County estimate |
| Alpaugh | 4.5 | 0.3 | Soft | County estimate |
| Llano | 171.0 | 10.0 | Hard | County estimate |
| Daggett | 111.0 | 6.5 | Moderately hard | County estimate |
| Callender | 105.0 | 6.1 | Moderately hard | Utility-reported |
| Dunnigan | 214.5 | 12.5 | Very hard | County estimate |
| Sheridan | 34.0 | 2.0 | Soft | County estimate |
| Orleans | 155.0 | 9.1 | Hard | County estimate |
| New Cuyama | 519.0 | 30.4 | Very hard | County estimate |
| Traver | 4.5 | 0.3 | Soft | County estimate |
| Hickman | 471.0 | 27.5 | Very hard | County estimate |
| Stinson Beach | 97.4 | 5.7 | Moderately hard | Utility-reported |
| Palo Verde | 150.0 | 8.8 | Hard | County estimate |
| River Pines | 85.2 | 5.0 | Moderately hard | County estimate |
| Fairmead | 88.0 | 5.2 | Moderately hard | Utility-reported |
| Crows Landing | 471.0 | 27.5 | Very hard | County estimate |
| Gerber | 113.0 | 6.6 | Moderately hard | County estimate |
| Twin Peaks | 111.0 | 6.5 | Moderately hard | County estimate |
| Salyer | 127.0 | 7.4 | Hard | County estimate |
| La Vina | 57.3 | 3.4 | Soft | Utility-reported |
| Hayfork | 127.0 | 7.4 | Hard | County estimate |
| Truckee | 37.0 | 2.2 | Soft | County estimate |
| Grimes | 143.4 | 8.4 | Hard | County estimate |
| Glenhaven | 99.5 | 5.8 | Moderately hard | County estimate |
| Greenbrae | 91.0 | 5.3 | Moderately hard | County estimate |
| Tahoe City | 34.0 | 2.0 | Soft | County estimate |
| Snelling | 137.5 | 8.0 | Hard | County estimate |
| Applegate | 34.0 | 2.0 | Soft | County estimate |
| Hopland | 102.0 | 6.0 | Moderately hard | County estimate |
| Korbel | 155.0 | 9.1 | Hard | County estimate |
| Moss Landing | 227.0 | 13.3 | Very hard | County estimate |
| Ballico | 137.5 | 8.0 | Hard | County estimate |
| Warner Springs | 366.0 | 21.4 | Very hard | County estimate |
| Woodbridge | 151.0 | 8.8 | Hard | County estimate |
| Newberry Springs | 111.0 | 6.5 | Moderately hard | County estimate |
| Mariposa | 5.4 | 0.3 | Soft | County estimate |
| Klamath | 87.7 | 5.1 | Moderately hard | County estimate |
| Lower Lake | 99.5 | 5.8 | Moderately hard | County estimate |
| Salton City | 150.0 | 8.8 | Hard | County estimate |
| Sanger | 202.0 | 11.8 | Very hard | County estimate |
| Tuolumne | 2.8 | 0.2 | Soft | County estimate |
| Acampo | 151.0 | 8.8 | Hard | County estimate |
| Mineral | 113.0 | 6.6 | Moderately hard | County estimate |
| Mountain Center | 186.0 | 10.9 | Very hard | County estimate |
| Cassel | 73.1 | 4.3 | Moderately hard | County estimate |
| Walnut Grove | 66.9 | 3.9 | Moderately hard | County estimate |
| Santa Ysabel | 366.0 | 21.4 | Very hard | County estimate |
| Ventura | 400.0 | 23.4 | Very hard | County estimate |
| Caruthers | 202.0 | 11.8 | Very hard | County estimate |
| Springville | 4.5 | 0.3 | Soft | County estimate |
| Colfax | 34.0 | 2.0 | Soft | County estimate |
| St. Helena | 108.0 | 6.3 | Moderately hard | County estimate |
| Studio City | 171.0 | 10.0 | Hard | County estimate |
| Los Banos | 137.5 | 8.0 | Hard | County estimate |
| Old Station | 73.1 | 4.3 | Moderately hard | County estimate |
| Santa Paula | 383.0 | 22.4 | Very hard | Utility-reported |
| Encino | 171.0 | 10.0 | Hard | County estimate |
| Nelson | 111.0 | 6.5 | Moderately hard | County estimate |
| Guerneville | 120.0 | 7.0 | Moderately hard | County estimate |
| Somerset | 100.0 | 5.8 | Moderately hard | Utility-reported |
| Five Points | 202.0 | 11.8 | Very hard | County estimate |
| Markleeville | 31.0 | 1.8 | Soft | County estimate |
| La Jolla | 366.0 | 21.4 | Very hard | County estimate |
| Galt | 66.9 | 3.9 | Moderately hard | County estimate |
| Zamora | 214.5 | 12.5 | Very hard | County estimate |
| Fowler | 202.0 | 11.8 | Very hard | County estimate |
| Nicasio | 91.0 | 5.3 | Moderately hard | County estimate |
| Riverdale | 202.0 | 11.8 | Very hard | County estimate |
| Colusa | 33.3 | 1.9 | Soft | Utility-reported |
| Cantil | 181.0 | 10.6 | Very hard | County estimate |
| Fawnskin | 111.0 | 6.5 | Moderately hard | County estimate |
| Orland | 356.0 | 20.8 | Very hard | Utility-reported |
| Acton | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Agua Dulce | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Angelus Oaks | 111.0 | 6.5 | Moderately hard | County estimate |
| Boron | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Bridgeport | 84.6 | 5.0 | Moderately hard | County estimate |
| Elizabeth Lake | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Frazier Park | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Green Valley | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Grizzly Flats | 32.8 | 1.9 | Soft | County estimate |
| Independence | 71.3 | 4.2 | Moderately hard | County estimate |
| La Canada Flintridge | 242.0 | 14.2 | Very hard | Utility-reported |
| Lake Hughes | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Lebec | 70.2 | 4.1 | Moderately hard | Utility-reported |
| Loyalton | 34.0 | 2.0 | Soft | County estimate |
| Morgan Hill | 49.1 | 2.9 | Soft | Utility-reported |
| Piru | 383.0 | 22.4 | Very hard | Utility-reported |
| Somis | 52.0 | 3.0 | Soft | Utility-reported |
Above 120 mg/L (7 gpg), scale is usually worth treating — see our water softener guide, or size a system with the hardness calculator & converter.
The Geology Behind California's Water Hardness
California sits in the California's split supplies region.
California splits sharply by source. Sierra Nevada snowmelt delivered through systems like Hetch Hetchy is soft, granite-filtered water, while the Central Valley and Southern California groundwater basins - filled with carbonate-rich alluvial sediment - and imported Colorado River water run hard to very hard. Two neighboring cities can therefore sit at opposite ends of the hardness scale depending on their supply mix.
California Water Hardness FAQ
Does California have hard water?
On the whole, no — California's statewide median sits below the hard threshold, though some cities run harder. The median is 98.4 mg/L (5.8 gpg) — moderately hard on the USGS scale, where anything above 120 mg/L (7 gpg) counts as hard. 291 of California's 772 measured cities fall in the hard or very hard bands (38%), so check your own city rather than the state average.
How hard is tap water in California?
Across the 772 California cities with measured values in our index, the median hardness is 98.4 mg/L (5.8 gpg) — moderately hard on the USGS scale. Individual cities range from 3.3 to 604.0 mg/L, so check your own city rather than assuming the state number.
Which city in California has the hardest water?
Los Berros has the hardest measured tap water in our California index at 604.0 mg/L (35.3 gpg) — very hard on the USGS scale. Rankings use measured utility values only; labeled county estimates and values under active dispute are excluded.
Do I need a water softener in California?
291 of California's 772 measured cities (38%) fall in the hard or very hard bands — above 120 mg/L (7 gpg), the level where most water treatment professionals suggest considering an ion-exchange softener. Hardness varies utility to utility, so look up your own city's value before sizing equipment.
How do I find my city's exact water hardness?
Enter your ZIP code in our free lookup at tapwaterdata.com/zip to see the value we hold for your California city from utility-reported water quality data, check your water utility's annual Consumer Confidence Report (CCR), or use a home test-strip kit.
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