Water Hardness in California
Across 597 measured cities — with 330 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 September 13, 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
597
utility-reported or computed values
County Estimates
330
36% of covered cities
What it costs to soften California water
Water softener cost in California at 5.8 gpg prices the equipment and the installation labour against the plumber wages published for California, and labels every range as modelled or measured rather than leaving you to guess which it is.
California · 5.75 grains per gallon
$974–$1,289
installed, midpoint $1,114 — a 24,000-grain unit, the size 4 people at this hardness need.
Salt and drain water over 10 years: $652–$1,282 — the 6,296,250 grains of hardness this household removes, at the national salt price and water rate whose sources are named below. Filter changes and Service contract are omitted rather than assumed.
Sized for 4 people regenerating every 7 days: 12,075 grains of capacity needed, rounded up to the next common residential size. The median of 597 measured California cities in our hardness dataset. Modelled: the standard build band published for that state at the size this hardness calls for, equipment priced 2026-10-04 against the May 2025 reference period (OEWS M2025). Salt: the median retailer price of 3 retailers, read 2026-10-04, at a declared salt dose per regeneration. Drain water: about 50 gallons per regeneration from a government extension estimate read 2026-10-04, at the 2024 national average water and sewer rate from a government source read 2026-10-04.
Deciding whether it is worth it at all? Start from how much a water softener costs nationally — the same equipment, installation and ten-year ownership breakdown before any state wage adjustment is applied.
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 | 192 | 32.2% |
| Moderately hard | 60-120 mg/L | 181 | 30.3% |
| Hard | 120-180 mg/L | 125 | 20.9% |
| Very hard | >180 mg/L | 99 | 16.6% |
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
- San Buenaventura (Ventura) — 505.0 mg/L (29.5 gpg), very hard
- Saticoy — 505.0 mg/L (29.5 gpg), very hard
- Anaheim — 329.0 mg/L (19.2 gpg), very hard
Softest water in California
- La Canada — 3.3 mg/L (0.2 gpg), soft
- Nevada City — 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
- Loma Linda — 6.9 mg/L (0.4 gpg), soft
Every Covered City in California
All 927 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 |
|---|---|---|---|---|
| Los Angeles | 121.0 | 7.1 | Hard | Utility-reported |
| Alameda | 33.7 | 2.0 | Soft | Utility-reported |
| Alamo | 33.7 | 2.0 | Soft | Utility-reported |
| Albany | 33.7 | 2.0 | Soft | Utility-reported |
| Ashland | 33.7 | 2.0 | Soft | Utility-reported |
| Bayview | 33.7 | 2.0 | Soft | Utility-reported |
| Berkeley | 33.7 | 2.0 | Soft | Utility-reported |
| Blackhawk | 33.7 | 2.0 | Soft | Utility-reported |
| Castro Valley | 33.7 | 2.0 | Soft | Utility-reported |
| Cherryland | 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 |
| El Cerrito | 33.7 | 2.0 | Soft | Utility-reported |
| El Sobrante | 33.7 | 2.0 | Soft | Utility-reported |
| Emeryville | 33.7 | 2.0 | Soft | Utility-reported |
| Fairview | 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 |
| Moraga | 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 |
| Richmond | 33.7 | 2.0 | Soft | Utility-reported |
| Rodeo | 33.7 | 2.0 | Soft | Utility-reported |
| San Leandro | 33.7 | 2.0 | Soft | Utility-reported |
| San Lorenzo | 33.7 | 2.0 | Soft | Utility-reported |
| San Pablo | 33.7 | 2.0 | Soft | Utility-reported |
| San Ramon | 33.7 | 2.0 | Soft | Utility-reported |
| San Diego | 225.0 | 13.2 | Very hard | Utility-reported |
| Fresno | 9.6 | 0.6 | Soft | Computed from Ca+Mg |
| 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 |
| Los Gatos | 178.0 | 10.4 | Hard | Utility-reported |
| Monte Sereno | 178.0 | 10.4 | Hard | Utility-reported |
| San Jose | 178.0 | 10.4 | Hard | Utility-reported |
| Saratoga | 178.0 | 10.4 | Hard | Utility-reported |
| San Francisco | 24.5 | 1.4 | Soft | Utility-reported |
| Beaumont | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Canyon Lake | 120.0 | 7.0 | Moderately hard | Utility-reported |
| East Hemet | 120.0 | 7.0 | 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 |
| Lakeview | 120.0 | 7.0 | Moderately hard | Utility-reported |
| March ARB | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Mead Valley | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Menifee | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Moreno Valley | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Murrieta | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Perris | 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 |
| Temecula | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Valle Vista | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Winchester | 120.0 | 7.0 | Moderately hard | Utility-reported |
| Sacramento | 25.1 | 1.5 | Soft | Utility-reported |
| Hawaiian Gardens | 171.0 | 10.0 | Hard | County estimate |
| Signal Hill | 171.0 | 10.0 | Hard | County estimate |
| Long Beach | 171.0 | 10.0 | Hard | County estimate |
| Costa Mesa | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Irvine | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Laguna Beach | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Laguna Woods | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Lake Forest | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Modjeska | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Silverado | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Fremont | 65.1 | 3.8 | Moderately hard | Utility-reported |
| Newark | 65.1 | 3.8 | Moderately hard | Utility-reported |
| Union City | 65.1 | 3.8 | Moderately hard | Utility-reported |
| Anaheim | 329.0 | 19.2 | Very hard | Utility-reported |
| Santa Ana | 219.0 | 12.8 | Very hard | Utility-reported |
| Riverside | 88.4 | 5.2 | Moderately hard | Utility-reported |
| Bostonia | 150.0 | 8.8 | Hard | Utility-reported |
| Casa de Oro-Mount Helix | 150.0 | 8.8 | Hard | Utility-reported |
| El Cajon | 150.0 | 8.8 | Hard | Utility-reported |
| Granite Hills | 150.0 | 8.8 | Hard | Utility-reported |
| La Mesa | 150.0 | 8.8 | Hard | Utility-reported |
| La Presa | 150.0 | 8.8 | Hard | Utility-reported |
| Lemon Grove | 150.0 | 8.8 | Hard | Utility-reported |
| Rancho San Diego | 150.0 | 8.8 | Hard | Utility-reported |
| Winter Gardens | 150.0 | 8.8 | Hard | Utility-reported |
| Alondra Park | 185.0 | 10.8 | Very hard | Utility-reported |
| Carson | 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 |
| Lawndale | 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 |
| West Rancho Dominguez | 185.0 | 10.8 | Very hard | Utility-reported |
| Westmont | 185.0 | 10.8 | Very hard | Utility-reported |
| Bermuda Dunes | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Cathedral City | 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 |
| Palm Desert | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Palm Springs | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Rancho Mirage | 113.0 | 6.6 | Moderately hard | Utility-reported |
| Sky Valley | 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 |
| Bakersfield Country Club | 36.9 | 2.2 | Soft | Utility-reported |
| Benton Park | 36.9 | 2.2 | Soft | Utility-reported |
| Casa Loma | 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 |
| Avocado Heights | 33.7 | 2.0 | Soft | Utility-reported |
| Baldwin Park | 33.7 | 2.0 | Soft | Utility-reported |
| Hacienda Heights | 33.7 | 2.0 | Soft | Utility-reported |
| La Puente | 33.7 | 2.0 | Soft | Utility-reported |
| Montebello | 33.7 | 2.0 | Soft | Utility-reported |
| Rose Hills | 33.7 | 2.0 | Soft | Utility-reported |
| Rosemead | 33.7 | 2.0 | Soft | Utility-reported |
| South El Monte | 33.7 | 2.0 | Soft | Utility-reported |
| South San Gabriel | 33.7 | 2.0 | Soft | Utility-reported |
| West Puente Valley | 33.7 | 2.0 | Soft | Utility-reported |
| West Whittier-Los Nietos | 33.7 | 2.0 | Soft | Utility-reported |
| Bloomington | 55.4 | 3.2 | Soft | Utility-reported |
| Fontana | 55.4 | 3.2 | Soft | Utility-reported |
| Rancho Cucamonga | 55.4 | 3.2 | Soft | Utility-reported |
| Bonita | 289.0 | 16.9 | Very hard | Utility-reported |
| Chula Vista | 289.0 | 16.9 | Very hard | Utility-reported |
| Crest | 289.0 | 16.9 | Very hard | Utility-reported |
| Jamul | 289.0 | 16.9 | Very hard | Utility-reported |
| Modesto | 44.5 | 2.6 | Soft | Utility-reported |
| San Bernardino | 33.5 | 2.0 | Soft | Utility-reported |
| Lancaster | 171.0 | 10.0 | Hard | County estimate |
| Glendale | 86.4 | 5.0 | Moderately hard | Utility-reported |
| Huntington Beach | 128.0 | 7.5 | Hard | Utility-reported |
| El Rio | 278.0 | 16.3 | Very hard | Utility-reported |
| Oxnard | 278.0 | 16.3 | Very hard | Utility-reported |
| Alhambra Valley | 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 |
| Clayton | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Clyde | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Concord | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Contra Costa Centre | 86.5 | 5.1 | Moderately hard | Utility-reported |
| North Gate | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Oakley | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Pacheco | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Pleasant Hill | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Shell Ridge | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Vine Hill | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Walnut Creek | 86.5 | 5.1 | Moderately hard | Utility-reported |
| Arden-Arcade | 97.8 | 5.7 | Moderately hard | Utility-reported |
| Foothill Farms | 97.8 | 5.7 | Moderately hard | Utility-reported |
| La Riviera | 97.8 | 5.7 | 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 |
| Fairfax | 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 |
| Lucas Valley-Marinwood | 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 |
| Novato | 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 |
| Sausalito | 55.8 | 3.3 | Soft | Utility-reported |
| Sleepy Hollow | 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 |
| National City | 128.0 | 7.5 | Hard | Utility-reported |
| Ontario | 127.0 | 7.4 | Hard | Utility-reported |
| Stockton | 10.2 | 0.6 | Soft | Computed from Ca+Mg |
| Oceanside | 169.0 | 9.9 | Hard | Utility-reported |
| Santa Rosa | 121.0 | 7.1 | Hard | Utility-reported |
| Elk Grove | 49.5 | 2.9 | Soft | Utility-reported |
| Vineyard | 49.5 | 2.9 | Soft | Utility-reported |
| Garden Grove | 283.0 | 16.6 | Very hard | Utility-reported |
| Pasadena | 230.0 | 13.4 | Very hard | Utility-reported |
| Aliso Viejo | 151.0 | 8.8 | Hard | Utility-reported |
| Dana Point | 151.0 | 8.8 | Hard | Utility-reported |
| Laguna Hills | 151.0 | 8.8 | Hard | Utility-reported |
| Laguna Niguel | 151.0 | 8.8 | Hard | Utility-reported |
| Mission Viejo | 151.0 | 8.8 | Hard | Utility-reported |
| South San Jose Hills | 223.0 | 13.0 | Very hard | Utility-reported |
| Valinda | 223.0 | 13.0 | Very hard | Utility-reported |
| Walnut | 223.0 | 13.0 | Very hard | Utility-reported |
| West Covina | 223.0 | 13.0 | Very 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 |
| Rancho Santa Margarita | 158.0 | 9.2 | Hard | Utility-reported |
| Lake Elsinore | 96.4 | 5.6 | Moderately hard | Utility-reported |
| Lakeland Village | 96.4 | 5.6 | Moderately hard | Utility-reported |
| Meadowbrook | 96.4 | 5.6 | Moderately hard | Utility-reported |
| Warm Springs | 96.4 | 5.6 | Moderately hard | Utility-reported |
| Wildomar | 96.4 | 5.6 | Moderately hard | Utility-reported |
| Hayward | 28.1 | 1.6 | Soft | Utility-reported |
| Corona | 161.0 | 9.4 | Hard | Utility-reported |
| Sunnyvale | 298.0 | 17.4 | Very hard | Utility-reported |
| Bakersfield | 27.4 | 1.6 | Soft | Utility-reported |
| East Los Angeles | 124.0 | 7.3 | Hard | Utility-reported |
| Pomona | 129.0 | 7.5 | Hard | Utility-reported |
| Visalia | 74.4 | 4.3 | Moderately hard | Utility-reported |
| West Carson | 53.7 | 3.1 | Soft | Computed from Ca+Mg |
| Roseville | 23.0 | 1.4 | Soft | Utility-reported |
| Fullerton | 175.0 | 10.2 | Hard | Utility-reported |
| Orange | 179.0 | 10.5 | Hard | Utility-reported |
| Escondido | 157.0 | 9.2 | Hard | Utility-reported |
| Eastvale | 97.9 | 5.7 | Moderately hard | Utility-reported |
| Jurupa Valley | 97.9 | 5.7 | Moderately hard | Utility-reported |
| San Marcos | 213.0 | 12.5 | Very hard | Utility-reported |
| Vista | 213.0 | 12.5 | Very hard | Utility-reported |
| Santa Clara | 248.0 | 14.5 | Very hard | 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 |
| Coloma | 14.3 | 0.8 | Soft | Utility-reported |
| Diamond Springs | 14.3 | 0.8 | Soft | Utility-reported |
| El Dorado Hills | 14.3 | 0.8 | Soft | Utility-reported |
| Pollock Pines | 14.3 | 0.8 | Soft | Utility-reported |
| Shingle Springs | 14.3 | 0.8 | Soft | Utility-reported |
| Palmdale | 60.4 | 3.5 | Moderately hard | Utility-reported |
| Vallejo | 81.3 | 4.8 | Moderately hard | Utility-reported |
| Clovis | 58.8 | 3.4 | Soft | Utility-reported |
| Mountain View Acres | 16.0 | 0.9 | Soft | Utility-reported |
| Victorville | 16.0 | 0.9 | Soft | Utility-reported |
| Fairfield | 109.0 | 6.4 | Moderately hard | Utility-reported |
| Huntington Park | 171.0 | 10.0 | Hard | County estimate |
| Antioch | 74.2 | 4.3 | Moderately hard | Utility-reported |
| San Buenaventura (Ventura) | 505.0 | 29.5 | Very hard | Utility-reported |
| Saticoy | 505.0 | 29.5 | Very 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 |
| Salinas | 106.0 | 6.2 | Moderately hard | Utility-reported |
| Downey | 255.0 | 14.9 | Very hard | Utility-reported |
| Chico | 154.0 | 9.0 | Hard | Utility-reported |
| Castaic | 236.0 | 13.8 | Very hard | Utility-reported |
| Newhall | 236.0 | 13.8 | Very hard | Utility-reported |
| Santa Clarita | 236.0 | 13.8 | Very hard | Utility-reported |
| Stevenson Ranch | 236.0 | 13.8 | Very hard | Utility-reported |
| Azusa | 112.0 | 6.5 | Moderately hard | Utility-reported |
| Citrus | 112.0 | 6.5 | Moderately hard | Utility-reported |
| Irwindale | 112.0 | 6.5 | Moderately hard | Utility-reported |
| Vincent | 112.0 | 6.5 | Moderately hard | Utility-reported |
| Santa Maria | 212.0 | 12.4 | Very hard | Utility-reported |
| Meyers | 45.7 | 2.7 | Soft | Computed from Ca+Mg |
| South Lake Tahoe | 45.7 | 2.7 | Soft | Computed from Ca+Mg |
| Daly City | 78.2 | 4.6 | Moderately hard | Utility-reported |
| Harmony Grove | 170.0 | 9.9 | Hard | Utility-reported |
| Hidden Meadows | 170.0 | 9.9 | Hard | Utility-reported |
| Lake San Marcos | 170.0 | 9.9 | Hard | Utility-reported |
| Torrance | 171.0 | 10.0 | Hard | County estimate |
| Coronado | 200.0 | 11.7 | Very hard | Utility-reported |
| Imperial Beach | 200.0 | 11.7 | Very hard | Utility-reported |
| Burbank | 159.0 | 9.3 | Hard | Utility-reported |
| Highland | 101.0 | 5.9 | Moderately hard | Utility-reported |
| Baywood Park | 37.6 | 2.2 | Soft | Utility-reported |
| Belmont | 37.6 | 2.2 | Soft | Utility-reported |
| Highlands | 37.6 | 2.2 | Soft | Utility-reported |
| San Mateo | 37.6 | 2.2 | Soft | Utility-reported |
| Diamond Bar | 153.0 | 8.9 | Hard | Utility-reported |
| Rowland Heights | 153.0 | 8.9 | Hard | Utility-reported |
| Midway City | 267.0 | 15.6 | Very hard | County estimate |
| Vacaville | 93.8 | 5.5 | Moderately hard | Utility-reported |
| Tracy | 67.2 | 3.9 | Moderately hard | Utility-reported |
| Hesperia | 108.0 | 6.3 | Moderately hard | Utility-reported |
| Homestead Valley | 108.0 | 6.3 | Moderately hard | Utility-reported |
| Yucca Valley | 108.0 | 6.3 | Moderately hard | Utility-reported |
| Hermosa Beach | 198.0 | 11.6 | Very hard | Utility-reported |
| Redondo Beach | 198.0 | 11.6 | Very hard | Utility-reported |
| Santa Barbara | 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 |
| Simi Valley | 161.0 | 9.4 | Hard | Utility-reported |
| Dublin | 195.0 | 11.4 | Very hard | Utility-reported |
| Carlsbad | 147.0 | 8.6 | Hard | Utility-reported |
| Merced | 137.5 | 8.0 | Hard | County estimate |
| Santa Monica | 57.4 | 3.4 | 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 |
| Del Rey Oaks | 167.0 | 9.8 | Hard | Utility-reported |
| Monterey | 167.0 | 9.8 | Hard | Utility-reported |
| Pacific Grove | 167.0 | 9.8 | Hard | Utility-reported |
| Sand City | 167.0 | 9.8 | Hard | Utility-reported |
| Seaside | 167.0 | 9.8 | Hard | Utility-reported |
| Lynwood | 171.0 | 10.0 | Hard | County estimate |
| Alpine | 209.0 | 12.2 | Very hard | Utility-reported |
| Eucalyptus Hills | 209.0 | 12.2 | Very hard | Utility-reported |
| Harbison Canyon | 209.0 | 12.2 | Very hard | Utility-reported |
| Santee | 209.0 | 12.2 | Very hard | Utility-reported |
| Redwood City | 32.2 | 1.9 | Soft | Utility-reported |
| Granite Bay | 11.3 | 0.7 | Soft | Utility-reported |
| Loomis | 11.3 | 0.7 | Soft | Utility-reported |
| Newcastle | 11.3 | 0.7 | Soft | Utility-reported |
| Penryn | 11.3 | 0.7 | Soft | Utility-reported |
| Rocklin | 11.3 | 0.7 | Soft | 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 |
| Whitewater | 213.0 | 12.5 | Very hard | Utility-reported |
| Capitola | 147.0 | 8.6 | Hard | Utility-reported |
| Pasatiempo | 147.0 | 8.6 | Hard | Utility-reported |
| Pleasure Point | 147.0 | 8.6 | Hard | Utility-reported |
| Santa Cruz | 147.0 | 8.6 | Hard | Utility-reported |
| Soquel | 147.0 | 8.6 | Hard | Utility-reported |
| Twin Lakes | 147.0 | 8.6 | Hard | Utility-reported |
| Redding | 29.8 | 1.7 | Soft | Utility-reported |
| Napa | 54.4 | 3.2 | Soft | Utility-reported |
| Elfin Forest | 129.0 | 7.5 | Hard | Utility-reported |
| Encinitas | 129.0 | 7.5 | Hard | Utility-reported |
| Fairbanks Ranch | 129.0 | 7.5 | Hard | Utility-reported |
| Rancho Santa Fe | 129.0 | 7.5 | Hard | Utility-reported |
| Solana Beach | 129.0 | 7.5 | Hard | Utility-reported |
| Manteca | 75.3 | 4.4 | Moderately hard | Utility-reported |
| Eastern Goleta Valley | 294.0 | 17.2 | Very 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 |
| Placentia | 48.2 | 2.8 | Soft | Computed from Ca+Mg |
| Yorba Linda | 48.2 | 2.8 | Soft | Computed from Ca+Mg |
| Alhambra | 149.0 | 8.7 | Hard | Utility-reported |
| Chino Hills | 81.4 | 4.8 | Moderately hard | Utility-reported |
| Chino | 111.0 | 6.5 | Moderately hard | County estimate |
| Inglewood | 227.0 | 13.3 | Very hard | Utility-reported |
| Buena Park | 154.0 | 9.0 | Hard | Utility-reported |
| Mountain View | 210.0 | 12.3 | Very hard | County estimate |
| Indio | 57.4 | 3.4 | Soft | Utility-reported |
| Coronita | 140.0 | 8.2 | Hard | Utility-reported |
| Highgrove | 140.0 | 8.2 | Hard | Utility-reported |
| Home Gardens | 140.0 | 8.2 | Hard | Utility-reported |
| Lake Mathews | 140.0 | 8.2 | Hard | Utility-reported |
| Woodcrest | 140.0 | 8.2 | Hard | Utility-reported |
| Pleasanton | 161.0 | 9.4 | Hard | Utility-reported |
| Upland | 126.0 | 7.4 | Hard | Utility-reported |
| Mentone | 64.3 | 3.8 | Moderately hard | Utility-reported |
| Redlands | 64.3 | 3.8 | Moderately hard | Utility-reported |
| Milpitas | 210.0 | 12.3 | Very hard | County estimate |
| South Gate | 217.0 | 12.7 | Very hard | Utility-reported |
| Yuba City | 247.0 | 14.4 | Very hard | County estimate |
| Compton | 171.0 | 10.0 | Hard | County estimate |
| Turlock | 98.3 | 5.8 | Moderately hard | Utility-reported |
| Bellflower | 119.0 | 7.0 | Moderately hard | Utility-reported |
| Agoura Hills | 76.6 | 4.5 | 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 |
| Rancho Palos Verdes | 171.0 | 10.0 | Hard | County estimate |
| Tulare | 37.0 | 2.2 | Soft | Utility-reported |
| Los Altos | 298.0 | 17.4 | Very hard | Utility-reported |
| Los Altos Hills | 298.0 | 17.4 | Very hard | Utility-reported |
| Loyola | 298.0 | 17.4 | Very hard | Utility-reported |
| Lodi | 4.3 | 0.3 | Soft | Computed from Ca+Mg |
| Newport Beach | 153.0 | 8.9 | Hard | Utility-reported |
| Folsom | 18.0 | 1.1 | Soft | Utility-reported |
| Palo Alto | 29.3 | 1.7 | Soft | Utility-reported |
| Madera | 94.0 | 5.5 | Moderately hard | County estimate |
| Citrus Heights | 48.4 | 2.8 | Soft | Utility-reported |
| Orangevale | 48.4 | 2.8 | Soft | Utility-reported |
| Casa Conejo | 111.0 | 6.5 | Moderately hard | Utility-reported |
| East Whittier | 233.0 | 13.6 | Very hard | Utility-reported |
| La Mirada | 233.0 | 13.6 | Very hard | Utility-reported |
| South Whittier | 233.0 | 13.6 | Very hard | Utility-reported |
| Tustin | 243.0 | 14.2 | Very hard | Utility-reported |
| Bell Gardens | 171.0 | 10.0 | Hard | County estimate |
| Watsonville | 215.0 | 12.6 | Very hard | Utility-reported |
| Brentwood | 376.0 | 22.0 | Very hard | County estimate |
| Petaluma | 105.0 | 6.1 | Moderately hard | Utility-reported |
| Broadmoor | 64.5 | 3.8 | Moderately hard | Utility-reported |
| Colma | 64.5 | 3.8 | Moderately hard | Utility-reported |
| South San Francisco | 64.5 | 3.8 | Moderately hard | Utility-reported |
| La Habra | 101.0 | 5.9 | Moderately hard | Utility-reported |
| Lakewood | 177.0 | 10.3 | Hard | Utility-reported |
| Porterville | 4.5 | 0.3 | Soft | County estimate |
| Apple Valley | 111.0 | 6.5 | Moderately hard | County estimate |
| Pittsburg | 69.0 | 4.0 | Moderately hard | Utility-reported |
| Monterey Park | 205.0 | 12.0 | Very 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 |
| Woodland | 43.7 | 2.6 | Soft | Utility-reported |
| Shafter | 181.0 | 10.6 | Very hard | County estimate |
| Gilroy | 113.0 | 6.6 | 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 |
| Charter Oak | 275.0 | 16.1 | Very hard | Utility-reported |
| San Dimas | 275.0 | 16.1 | Very hard | Utility-reported |
| Paramount | 108.0 | 6.3 | Moderately hard | Utility-reported |
| Rialto | 32.5 | 1.9 | Soft | Utility-reported |
| Mather | 38.4 | 2.3 | Soft | Utility-reported |
| Rancho Cordova | 38.4 | 2.3 | Soft | Utility-reported |
| Rosemont | 38.4 | 2.3 | Soft | Utility-reported |
| West Sacramento | 35.0 | 2.0 | Soft | Utility-reported |
| Thousand Oaks | 118.0 | 6.9 | Moderately hard | Utility-reported |
| Glendora | 144.0 | 8.4 | Hard | Utility-reported |
| Yucaipa | 95.4 | 5.6 | Moderately hard | Utility-reported |
| San Clemente | 200.0 | 11.7 | Very hard | Utility-reported |
| Lincoln | 20.5 | 1.2 | Soft | Utility-reported |
| Artesia | 171.0 | 10.0 | Hard | County estimate |
| Whittier | 171.0 | 10.0 | Hard | County estimate |
| Cerritos | 135.0 | 7.9 | Hard | Utility-reported |
| Calimesa | 161.0 | 9.4 | Hard | Utility-reported |
| Cherry Valley | 161.0 | 9.4 | Hard | Utility-reported |
| Poway | 194.0 | 11.3 | Very hard | Utility-reported |
| Florin | 66.1 | 3.9 | Moderately hard | Utility-reported |
| Parkway | 66.1 | 3.9 | Moderately hard | Utility-reported |
| Olivehurst | 148.5 | 8.7 | Hard | County estimate |
| Ceres | 165.0 | 9.7 | Hard | Utility-reported |
| San Luis Obispo | 470.0 | 27.5 | Very hard | County estimate |
| East San Gabriel | 115.0 | 6.7 | Moderately hard | Utility-reported |
| San Gabriel | 115.0 | 6.7 | Moderately hard | Utility-reported |
| San Marino | 115.0 | 6.7 | Moderately hard | Utility-reported |
| San Pasqual | 115.0 | 6.7 | Moderately hard | Utility-reported |
| Temple City | 115.0 | 6.7 | Moderately hard | Utility-reported |
| Morgan Hill | 210.0 | 12.3 | Very hard | County estimate |
| Gold River | 30.0 | 1.8 | Soft | Computed from Ca+Mg |
| Camarillo | 400.0 | 23.4 | Very hard | County estimate |
| Colton | 121.0 | 7.1 | Hard | Utility-reported |
| El Centro | 150.0 | 8.8 | Hard | County estimate |
| San Bruno | 255.0 | 14.9 | Very hard | County estimate |
| Coachella | 17.6 | 1.0 | Soft | Utility-reported |
| Brea | 191.0 | 11.2 | Very hard | Utility-reported |
| Arcadia | 165.0 | 9.7 | Hard | Utility-reported |
| Hawthorne | 140.0 | 8.2 | Hard | Utility-reported |
| Rohnert Park | 106.0 | 6.2 | Moderately hard | Utility-reported |
| Carmichael | 23.8 | 1.4 | Soft | Utility-reported |
| Aptos | 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 |
| Seacliff | 98.4 | 5.8 | Moderately hard | Utility-reported |
| Pico Rivera | 171.0 | 10.0 | Hard | County estimate |
| Calexico | 174.0 | 10.2 | Hard | Utility-reported |
| Beverly Hills | 171.0 | 10.0 | Hard | County estimate |
| Claremont | 160.0 | 9.4 | Hard | Utility-reported |
| San Juan Capistrano | 185.0 | 10.8 | Very hard | Utility-reported |
| Pacifica | 47.4 | 2.8 | Soft | Utility-reported |
| Marina | 142.0 | 8.3 | Hard | Utility-reported |
| Culver City | 174.0 | 10.2 | Hard | Utility-reported |
| Monrovia | 175.0 | 10.2 | Hard | Utility-reported |
| Moorpark | 190.0 | 11.1 | Very hard | Utility-reported |
| Foster City | 33.0 | 1.9 | Soft | Utility-reported |
| Livermore | 94.4 | 5.5 | Moderately hard | Utility-reported |
| Manhattan Beach | 215.0 | 12.6 | Very hard | Utility-reported |
| Lakeside | 154.0 | 9.0 | Hard | Utility-reported |
| Fair Oaks | 60.4 | 3.5 | Moderately hard | Utility-reported |
| Emerald Lake Hills | 32.4 | 1.9 | Soft | Utility-reported |
| San Carlos | 32.4 | 1.9 | Soft | Utility-reported |
| Fallbrook | 67.1 | 3.9 | Moderately hard | Utility-reported |
| Ramona | 84.9 | 5.0 | Moderately hard | Utility-reported |
| San Diego Country Estates | 84.9 | 5.0 | Moderately hard | Utility-reported |
| Antelope | 78.5 | 4.6 | Moderately hard | Utility-reported |
| Elverta | 78.5 | 4.6 | Moderately hard | Utility-reported |
| Orcutt | 233.0 | 13.6 | Very hard | Utility-reported |
| Covina | 171.0 | 10.0 | Hard | County estimate |
| Barstow | 111.0 | 6.5 | Moderately hard | County estimate |
| La Crescenta | 171.0 | 10.0 | Hard | County estimate |
| Hemet | 186.0 | 10.9 | Very hard | County estimate |
| Banning | 186.0 | 10.9 | Very hard | County estimate |
| La Verne | 153.0 | 8.9 | Hard | Utility-reported |
| 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 |
| Santa Paula | 400.0 | 23.4 | Very hard | County estimate |
| Atascadero | 39.0 | 2.3 | Soft | Computed from Ca+Mg |
| Valley Center | 223.0 | 13.0 | Very hard | Utility-reported |
| East Palo Alto | 46.3 | 2.7 | Soft | Utility-reported |
| Suisun City | 107.0 | 6.3 | Moderately hard | Utility-reported |
| Wasco | 181.0 | 10.6 | Very hard | County estimate |
| Martinez | 65.0 | 3.8 | Moderately hard | Utility-reported |
| Lathrop | 56.4 | 3.3 | Soft | Utility-reported |
| Windsor | 120.0 | 7.0 | Moderately hard | County estimate |
| Big Bear Lake | 177.0 | 10.3 | Hard | Utility-reported |
| Benicia | 53.2 | 3.1 | Soft | Utility-reported |
| Norco | 186.0 | 10.9 | Very hard | County estimate |
| Phelan | 111.0 | 6.5 | Moderately hard | County estimate |
| Eureka | 77.9 | 4.6 | Moderately hard | Utility-reported |
| Brawley | 150.0 | 8.8 | Hard | County estimate |
| Dinuba | 91.5 | 5.3 | Moderately hard | Utility-reported |
| Selma | 202.0 | 11.8 | Very hard | County estimate |
| Auburn | 10.6 | 0.6 | Soft | Utility-reported |
| Lemoore | 25.6 | 1.5 | Soft | Utility-reported |
| Reedley | 202.0 | 11.8 | Very hard | County estimate |
| Soledad | 227.0 | 13.3 | Very hard | County estimate |
| Riverbank | 196.0 | 11.5 | Very hard | Utility-reported |
| South Pasadena | 128.0 | 7.5 | Hard | Utility-reported |
| Loma Linda | 6.9 | 0.4 | Soft | 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 |
| San Fernando | 171.0 | 10.0 | Hard | County estimate |
| Patterson | 471.0 | 27.5 | Very hard | County estimate |
| Bay Point | 105.0 | 6.1 | Moderately hard | Utility-reported |
| Bonsall | 196.0 | 11.5 | Very hard | Utility-reported |
| Rainbow | 196.0 | 11.5 | Very hard | Utility-reported |
| Mountain House | 60.6 | 3.5 | Moderately hard | Utility-reported |
| Boyes Hot Springs | 61.5 | 3.6 | Moderately hard | Utility-reported |
| El Verano | 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 |
| El Monte | 68.3 | 4.0 | Moderately hard | Utility-reported |
| Oakdale | 91.7 | 5.4 | Moderately hard | Utility-reported |
| Millbrae | 43.8 | 2.6 | Soft | Utility-reported |
| Oroville | 111.0 | 6.5 | Moderately hard | County estimate |
| Palermo | 111.0 | 6.5 | Moderately hard | County estimate |
| Maricopa | 400.0 | 23.4 | Very hard | County estimate |
| Taft | 181.0 | 10.6 | Very hard | County estimate |
| Port Hueneme | 400.0 | 23.4 | Very hard | County estimate |
| Corcoran | 64.3 | 3.8 | Moderately hard | County estimate |
| Maywood | 171.0 | 10.0 | Hard | County estimate |
| Arcata | 155.0 | 9.1 | Hard | County estimate |
| Ben Lomond | 149.0 | 8.7 | Hard | Utility-reported |
| Boulder Creek | 149.0 | 8.7 | Hard | Utility-reported |
| Brookdale | 149.0 | 8.7 | Hard | Utility-reported |
| Lompico | 149.0 | 8.7 | Hard | Utility-reported |
| Zayante | 149.0 | 8.7 | Hard | Utility-reported |
| American Canyon | 64.6 | 3.8 | Moderately hard | Utility-reported |
| Ladera Heights | 264.0 | 15.4 | Very hard | Utility-reported |
| View Park-Windsor Hills | 264.0 | 15.4 | Very hard | Utility-reported |
| Lomita | 171.0 | 10.0 | Hard | County estimate |
| Imperial | 94.4 | 5.5 | Moderately hard | Utility-reported |
| Arvin | 181.0 | 10.6 | Very hard | County estimate |
| Temescal Valley | 68.8 | 4.0 | Moderately hard | Utility-reported |
| Oak Park | 133.0 | 7.8 | Hard | Utility-reported |
| Westlake Village | 133.0 | 7.8 | Hard | Utility-reported |
| Menlo Park | 44.9 | 2.6 | Soft | Utility-reported |
| Santa Fe Springs | 198.0 | 11.6 | Very hard | Utility-reported |
| Lamont | 181.0 | 10.6 | Very hard | County estimate |
| Grand Terrace | 111.0 | 6.5 | Moderately hard | County estimate |
| 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 |
| Moss Beach | 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 |
| Lucerne Valley | 111.0 | 6.5 | Moderately hard | County estimate |
| Arroyo Grande | 311.0 | 18.2 | Very hard | Utility-reported |
| San Jacinto | 186.0 | 10.9 | Very hard | County estimate |
| Norwalk | 171.0 | 10.0 | Hard | County estimate |
| Crescent City | 87.7 | 5.1 | Moderately hard | County estimate |
| Rosamond | 103.0 | 6.0 | Moderately hard | Utility-reported |
| Coalinga | 118.0 | 6.9 | Moderately hard | Utility-reported |
| Rough and Ready | 12.5 | 0.7 | Soft | Utility-reported |
| McKinleyville | 91.0 | 5.3 | 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 |
| Ukiah | 55.0 | 3.2 | Soft | Utility-reported |
| Cupertino | 210.0 | 12.3 | Very hard | County estimate |
| Fillmore | 400.0 | 23.4 | Very hard | County estimate |
| Ripon | 151.0 | 8.8 | Hard | County estimate |
| Altadena | 248.0 | 14.5 | Very hard | Utility-reported |
| Carpinteria | 519.0 | 30.4 | Very hard | County estimate |
| La Palma | 267.0 | 15.6 | Very hard | County estimate |
| Chowchilla | 94.0 | 5.5 | Moderately hard | County estimate |
| Morro Bay | 144.0 | 8.4 | Hard | Utility-reported |
| McFarland | 5.0 | 0.3 | Soft | Utility-reported |
| Kerman | 202.0 | 11.8 | Very hard | County estimate |
| 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 |
| Salida | 471.0 | 27.5 | Very hard | County estimate |
| Parlier | 202.0 | 11.8 | Very hard | County estimate |
| Rio Linda | 93.4 | 5.5 | Moderately hard | Utility-reported |
| California City | 73.3 | 4.3 | Moderately hard | Utility-reported |
| Alta Sierra | 15.5 | 0.9 | Soft | Utility-reported |
| Los Berros | 604.0 | 35.3 | Very hard | Utility-reported |
| Nipomo | 604.0 | 35.3 | Very hard | Utility-reported |
| Avenal | 64.3 | 3.8 | Moderately hard | County estimate |
| Trabuco Canyon | 150.0 | 8.8 | Hard | Utility-reported |
| Grover Beach | 470.0 | 27.5 | Very hard | County estimate |
| Big Bear City | 125.0 | 7.3 | Hard | Utility-reported |
| Lindsay | 4.5 | 0.3 | Soft | County estimate |
| Fortuna | 155.0 | 9.1 | Hard | County estimate |
| Marysville | 97.8 | 5.7 | Moderately hard | Utility-reported |
| Kingsburg | 91.3 | 5.3 | Moderately hard | Utility-reported |
| Summerland | 519.0 | 30.4 | Very hard | County estimate |
| Dixon | 152.0 | 8.9 | Hard | Utility-reported |
| Newman | 471.0 | 27.5 | Very hard | County estimate |
| Exeter | 4.5 | 0.3 | Soft | County estimate |
| Sonoma | 127.0 | 7.4 | Hard | Utility-reported |
| East Sonora | 44.1 | 2.6 | Soft | Utility-reported |
| Jamestown | 44.1 | 2.6 | Soft | Utility-reported |
| Greenfield | 227.0 | 13.3 | Very hard | County estimate |
| Mendota | 16.8 | 1.0 | Soft | Utility-reported |
| Hillsborough | 25.1 | 1.5 | Soft | Utility-reported |
| Cloverdale | 120.0 | 7.0 | Moderately hard | County estimate |
| Healdsburg | 93.3 | 5.5 | Moderately hard | Utility-reported |
| Anderson | 73.1 | 4.3 | Moderately hard | County estimate |
| Needles | 111.0 | 6.5 | Moderately hard | County estimate |
| Twain Harte | 2.8 | 0.2 | Soft | County estimate |
| Mira Monte | 186.0 | 10.9 | Very hard | Utility-reported |
| Oak View | 186.0 | 10.9 | Very hard | Utility-reported |
| 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 |
| Scotts Valley | 146.0 | 8.5 | Hard | Utility-reported |
| Shasta Lake | 73.1 | 4.3 | Moderately hard | County estimate |
| Rio Vista | 49.3 | 2.9 | Soft | Utility-reported |
| Crestline | 54.8 | 3.2 | Soft | Utility-reported |
| Carnelian Bay | 34.0 | 2.0 | Soft | County estimate |
| East Pasadena | 85.3 | 5.0 | Moderately hard | 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 |
| Clearlake | 88.6 | 5.2 | Moderately hard | Utility-reported |
| Winton | 137.5 | 8.0 | Hard | County estimate |
| 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 |
| Live Oak | 247.0 | 14.4 | Very hard | County estimate |
| Placerville | 32.8 | 1.9 | Soft | County estimate |
| Georgetown | 32.8 | 1.9 | Soft | County estimate |
| Lake Wildwood | 19.3 | 1.1 | Soft | Utility-reported |
| Penn Valley | 19.3 | 1.1 | Soft | Utility-reported |
| Tehachapi | 181.0 | 10.6 | Very hard | County estimate |
| Pioneer | 85.2 | 5.0 | Moderately hard | County estimate |
| Waterford | 471.0 | 27.5 | Very hard | County estimate |
| Gonzales | 227.0 | 13.3 | Very hard | County estimate |
| Joshua Tree | 70.4 | 4.1 | Moderately hard | Utility-reported |
| Orosi | 170.0 | 9.9 | Hard | Utility-reported |
| Orland | 245.0 | 14.3 | Very hard | County estimate |
| 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 |
| Delhi | 137.5 | 8.0 | Hard | County estimate |
| Earlimart | 4.5 | 0.3 | Soft | County estimate |
| Firebaugh | 121.0 | 7.1 | Hard | Utility-reported |
| Oceano | 470.0 | 27.5 | Very hard | County estimate |
| Sebastopol | 142.0 | 8.3 | Hard | Utility-reported |
| Escalon | 151.0 | 8.8 | Hard | County estimate |
| Cotati | 120.0 | 7.0 | Moderately hard | County estimate |
| Winters | 214.5 | 12.5 | Very hard | County estimate |
| Hughson | 471.0 | 27.5 | Very hard | County estimate |
| Nuevo | 161.0 | 9.4 | Hard | Utility-reported |
| Lake Arrowhead | 58.4 | 3.4 | Soft | Utility-reported |
| Heber | 53.2 | 3.1 | Soft | Utility-reported |
| North Auburn | 16.0 | 0.9 | Soft | Utility-reported |
| Foresthill | 34.0 | 2.0 | Soft | County estimate |
| Ojai | 297.0 | 17.4 | Very hard | Utility-reported |
| Colusa | 143.4 | 8.4 | Hard | County estimate |
| Madera Acres | 61.5 | 3.6 | Moderately hard | Utility-reported |
| Mokelumne Hill | 29.2 | 1.7 | Soft | Utility-reported |
| Paloma | 29.2 | 1.7 | Soft | Utility-reported |
| San Andreas | 29.2 | 1.7 | Soft | Utility-reported |
| Cutler | 4.5 | 0.3 | Soft | County estimate |
| 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 |
| Keyes | 471.0 | 27.5 | Very hard | County estimate |
| Villa Park | 252.0 | 14.7 | Very hard | Utility-reported |
| Tahoe City | 65.0 | 3.8 | Moderately hard | Utility-reported |
| Bear Valley Springs | 158.0 | 9.2 | Hard | Utility-reported |
| Hilmar | 137.5 | 8.0 | Hard | County estimate |
| 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 |
| Spreckels | 257.0 | 15.0 | Very hard | Utility-reported |
| Denair | 118.0 | 6.9 | Moderately hard | Utility-reported |
| Running Springs | 30.7 | 1.8 | Soft | Utility-reported |
| Copperopolis | 28.3 | 1.6 | Soft | Utility-reported |
| Meadow Vista | 34.0 | 2.0 | Soft | County estimate |
| Grass Valley | 12.9 | 0.8 | Soft | Utility-reported |
| Amador City | 85.2 | 5.0 | Moderately hard | County estimate |
| Sutter Creek | 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 |
| Represa | 66.9 | 3.9 | Moderately hard | County estimate |
| Angwin | 108.0 | 6.3 | Moderately hard | County estimate |
| Mojave | 181.0 | 10.6 | Very hard | County estimate |
| Murphys | 101.7 | 6.0 | Moderately hard | County estimate |
| Planada | 137.5 | 8.0 | Hard | County estimate |
| Ivanhoe | 250.0 | 14.6 | Very hard | Utility-reported |
| Felton | 117.0 | 6.8 | Moderately hard | Utility-reported |
| North Lakeport | 63.7 | 3.7 | Moderately hard | Utility-reported |
| Del Mar | 366.0 | 21.4 | Very hard | County estimate |
| Commerce | 75.0 | 4.4 | Moderately hard | Utility-reported |
| Meiners Oaks | 225.0 | 13.2 | Very 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 |
| Wheatland | 148.5 | 8.7 | Hard | County estimate |
| Mount Shasta | 89.3 | 5.2 | Moderately hard | County estimate |
| Hoopa | 155.0 | 9.1 | Hard | County estimate |
| Borrego Springs | 366.0 | 21.4 | Very hard | County estimate |
| Groveland | 2.8 | 0.2 | Soft | County estimate |
| Brisbane | 25.8 | 1.5 | Soft | Utility-reported |
| Cottonwood | 113.0 | 6.6 | Moderately hard | County estimate |
| 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 |
| Nevada City | 3.3 | 0.2 | Soft | Computed from Ca+Mg |
| Littlerock | 171.0 | 10.0 | Hard | County estimate |
| 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 |
| Idyllwild | 30.8 | 1.8 | Soft | Utility-reported |
| Idyllwild-Pine Cove | 30.8 | 1.8 | Soft | Utility-reported |
| Sutter | 247.0 | 14.4 | Very hard | County estimate |
| 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 |
| 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 |
| Ferndale | 75.9 | 4.4 | Moderately hard | Utility-reported |
| Pine Valley | 366.0 | 21.4 | Very hard | County estimate |
| Cedarpines Park | 34.9 | 2.0 | Soft | Utility-reported |
| Lockeford | 98.0 | 5.7 | Moderately hard | Utility-reported |
| Bolinas | 91.0 | 5.3 | Moderately hard | County estimate |
| Cayucos | 470.0 | 27.5 | Very 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 |
| Lucerne | 94.3 | 5.5 | Moderately hard | Utility-reported |
| 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 |
| 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 |
| 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 |
| Hamilton City | 245.0 | 14.3 | Very hard | County estimate |
| Linden | 151.0 | 8.8 | Hard | County estimate |
| Sonora | 2.8 | 0.2 | Soft | County estimate |
| Tuolumne City | 11.9 | 0.7 | Soft | Utility-reported |
| Lost Hills | 181.0 | 10.6 | Very hard | County estimate |
| 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 |
| Parkwood | 133.0 | 7.8 | Hard | Utility-reported |
| 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 |
| Spring Valley | 366.0 | 21.4 | Very hard | County estimate |
| Pine Mountain Club | 181.0 | 10.6 | Very hard | County estimate |
| Le Grand | 137.5 | 8.0 | Hard | County estimate |
| Isleton | 21.8 | 1.3 | Soft | Utility-reported |
| Durham | 111.0 | 6.5 | Moderately hard | County estimate |
| East Oakdale | 230.0 | 13.4 | Very hard | Utility-reported |
| Laton | 54.3 | 3.2 | Soft | Utility-reported |
| Fall River Mills | 73.1 | 4.3 | Moderately hard | County estimate |
| Buttonwillow | 181.0 | 10.6 | Very hard | County estimate |
| Julian | 31.3 | 1.8 | Soft | Utility-reported |
| Willow Creek | 99.0 | 5.8 | Moderately hard | Utility-reported |
| 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 |
| Mccloud | 89.3 | 5.2 | Moderately hard | County estimate |
| 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 |
| Strawberry | 2.8 | 0.2 | Soft | County estimate |
| 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 |
| Garberville | 155.0 | 9.1 | Hard | County estimate |
| Redway | 155.0 | 9.1 | Hard | County estimate |
| Maxwell | 143.4 | 8.4 | Hard | County estimate |
| San Martin | 210.0 | 12.3 | Very hard | County estimate |
| Camp Meeker | 120.0 | 7.0 | Moderately hard | County estimate |
| Kettleman City | 37.0 | 2.2 | 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 |
| 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 |
| Valley Springs | 101.7 | 6.0 | Moderately hard | County estimate |
| Pauma Valley | 366.0 | 21.4 | Very 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 |
| 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 |
| Palo Verde | 150.0 | 8.8 | Hard | County estimate |
| River Pines | 85.2 | 5.0 | Moderately hard | County estimate |
| 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 |
| 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 |
| 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 |
| 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 |
| Knightsen | 376.0 | 22.0 | Very hard | County estimate |
| 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 |
| Cantil | 181.0 | 10.6 | Very hard | County estimate |
| Fawnskin | 111.0 | 6.5 | Moderately hard | County estimate |
| Acton | 171.0 | 10.0 | Hard | County estimate |
| Angelus Oaks | 111.0 | 6.5 | Moderately hard | County estimate |
| Boron | 181.0 | 10.6 | Very hard | County estimate |
| Bridgeport | 84.6 | 5.0 | Moderately hard | County estimate |
| Camp Pendleton | 366.0 | 21.4 | Very hard | County estimate |
| Carmel | 227.0 | 13.3 | Very hard | County estimate |
| Elmira | 256.0 | 15.0 | Very hard | County estimate |
| Empire | 471.0 | 27.5 | Very hard | County estimate |
| Forest Falls | 111.0 | 6.5 | Moderately hard | County estimate |
| Fort Irwin | 111.0 | 6.5 | Moderately hard | County estimate |
| Frazier Park | 400.0 | 23.4 | Very hard | County estimate |
| Freedom | 210.0 | 12.3 | Very hard | County estimate |
| French Camp | 151.0 | 8.8 | Hard | County estimate |
| Grizzly Flats | 32.8 | 1.9 | Soft | County estimate |
| Independence | 71.3 | 4.2 | Moderately hard | County estimate |
| La Canada Flintridge | 171.0 | 10.0 | Hard | County estimate |
| Lake Hughes | 171.0 | 10.0 | Hard | County estimate |
| Lebec | 181.0 | 10.6 | Very hard | County estimate |
| Loyalton | 34.0 | 2.0 | Soft | County estimate |
| Marina del Rey | 171.0 | 10.0 | Hard | County estimate |
| Oakhurst | 94.0 | 5.5 | Moderately hard | County estimate |
| Piru | 400.0 | 23.4 | Very hard | County estimate |
| San Miguel | 227.0 | 13.3 | Very hard | County estimate |
| Somerset | 32.8 | 1.9 | Soft | County estimate |
| Somis | 400.0 | 23.4 | Very hard | County estimate |
| Stanford | 210.0 | 12.3 | Very hard | County estimate |
| Stinson Beach | 91.0 | 5.3 | Moderately hard | County estimate |
| Sunol | 275.0 | 16.1 | Very hard | County estimate |
| Tahoma | 32.8 | 1.9 | Soft | County estimate |
| Three Rivers | 4.5 | 0.3 | Soft | County estimate |
| West Hollywood | 171.0 | 10.0 | Hard | County estimate |
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. 224 of California's 597 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 597 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?
224 of California's 597 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.
Need whole-house or professional water treatment?
For the problems a pitcher or under-sink filter cannot fix — scale, rust and black staining, sulfur smell, well contamination, or test results you cannot explain. Tell us what is happening and we will connect you with a local water-treatment professional.
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