Backflow Testing in California
Backflow Testing across California: the 1,921 ZIP codes and 726 cities we route calls in, and who licenses plumbers in the state.
Free to homeowners in California — the contractor pays us for the introduction, you never do.
Who has to test
Our backflow testing coverage in California runs to 1,921 ZIP codes in 726 cities. Backflow assemblies are required where a premises can push water back into the main, and in a state of large municipalities that duty is usually written into one city-wide water ordinance that applies the same way across tens of thousands of connections.
Source: coverage area as published by our call partner; place and county names from the US Census Bureau.
We route backflow testing calls in 1,921 ZIP codes across 726 California cities, in 40 counties.
What this site is
CrossConnect is a referral service, not a contractor. We connect property owners and managers with independent contractors. Backflow assembly testing is normally restricted to testers holding a specific certification and using calibrated equipment, and the report usually has to reach your water purveyor — ask to see the certification and ask who files the report. We carry out no testing, we certify nobody, we do not set prices, and we never charge callers anything. Nothing here selects a device for any installation or states that any assembly is passing.Checking a credential in California
California licenses are issued by the Contractors State License Board, which publishes a public search you can use before work begins. California licenses the C-36 plumbing contractor; there is no state journeyman license.
18 of the 40 California counties we cover, from the top of the alphabet
- Alameda County 68 ZIP codes
Oakland, Berkeley, Hayward, Fremont, San Leandro, Alameda, Castro Valley, Emeryville, Livermore, Pleasanton, Albany, Dublin, Newark, San Lorenzo and 2 more - Amador County 8 ZIP codes
Amador City, Drytown, Ione, Jackson, Pine Grove, Pioneer, Plymouth, Sutter Creek - Butte County 19 ZIP codes
Chico, Oroville, Paradise, Bangor, Biggs, Durham, Forest Ranch, Gridley, Magalia, Nelson, Palermo, Richvale - Calaveras County 8 ZIP codes
Angels Camp, Burson, Campo Seco, Copperopolis, Mokelumne Hill, San Andreas, Valley Springs, Wallace - Colusa County 3 ZIP codes
Colusa, Maxwell, Princeton - Contra Costa County 52 ZIP codes
Concord, Richmond, Walnut Creek, Moraga, Antioch, Danville, El Sobrante, San Ramon, Alamo, Bethel Island, Brentwood, Byron, Canyon, Clayton and 16 more - El Dorado County 17 ZIP codes
Camino, Coloma, Cool, Diamond Springs, El Dorado, El Dorado Hills, Garden Valley, Georgetown, Greenwood, Lotus, Pilot Hill, Placerville, Pollock Pines, Rescue and 3 more - Fresno County 13 ZIP codes
Fresno, Clovis - Glenn County 6 ZIP codes
Artois, Butte City, Glenn, Hamilton City, Orland, Willows - Humboldt County 21 ZIP codes
Eureka, Arcata, Bayside, Blue Lake, Carlotta, Ferndale, Fields Landing, Fortuna, Hydesville, Kneeland, Korbel, Loleta, McKinleyville, Rio Dell and 4 more - Kern County 12 ZIP codes
Boron, California City, Cantil, Edwards, Inyokern, Keene, Maricopa, Mojave, Randsburg, Ridgecrest, Rosamond, Tehachapi - Los Angeles County 494 ZIP codes
Los Angeles, Long Beach, Pasadena, Glendale, Burbank, Van Nuys, Inglewood, North Hollywood, Santa Monica, Torrance, Whittier, Alhambra, Northridge, Beverly Hills and 112 more - Marin County 40 ZIP codes
Novato, San Rafael, Corte Madera, Fairfax, Larkspur, Mill Valley, San Anselmo, San Quentin, Sausalito, Belvedere Tiburon, Bolinas, Dillon Beach, Forest Knolls, Greenbrae and 11 more - Merced County 13 ZIP codes
Merced, Atwater, Delhi, Gustine, Hilmar, Livingston, Los Banos, Snelling, Winton - Monterey County 21 ZIP codes
Salinas, Monterey, Carmel, Aromas, Carmel by the Sea, Castroville, Marina, Moss Landing, Pacific Grove, Pebble Beach, Seaside - Napa County 12 ZIP codes
Napa, American Canyon, Angwin, Calistoga, Deer Park, Oakville, Pope Valley, Rutherford, Saint Helena, Yountville - Nevada County 1 ZIP code
Truckee - Orange County 144 ZIP codes
Anaheim, Irvine, Santa Ana, Orange, Fullerton, Garden Grove, Huntington Beach, Newport Beach, Buena Park, Brea, Costa Mesa, La Habra, Mission Viejo, San Clemente and 30 more
22 more California counties are inside the coverage area and are not listed here. If your ZIP code is in California, the call reaches a contractor.
What that coverage looks like
The 40 counties in our California footprint are served by many separate water suppliers, and each one decides which premises must test and how often. Los Angeles County, with 494 covered ZIP codes, is the largest single block of them; Sacramento alone holds 100.
How a backflow testing job goes
A backflow test is a scheduled job that ends in a document. The assembly is isolated, the differential across it is measured, the result is written down, and the report goes to whoever requires it. A failed test means a repair or a rebuild and then a re-test; it does not mean the premises closes that day.
What the call asks about backflow testing
- What kind of premises it is and what is connected to the supply — irrigation, a boiler, a fire line, a commercial kitchen.
- Who is asking for the test: a water supplier, a health department, or a landlord.
- Whether there is an existing assembly with a serial number on it, and when it was last tested.
Every California city we route in
392 cities, ordered by the share of buildings with twenty or more units. Containment assemblies are required building by building, and that is where the buildings are. Each page carries that city’s own numbers and the ZIP codes we route there.
- Playa Vista 86%
- Marina del Rey 74%
- Playa del Rey 49%
- Stanford 48%
- West Hollywood 48%
- Panorama City 47%
- Emeryville 40%
- Canoga Park 40%
- Encino 38%
- Northridge 37%
- Valley Village 36%
- Woodland Hills 35%
- Van Nuys 35%
- Sherman Oaks 34%
- Tarzana 33%
- North Hollywood 32%
- Mountain View 32%
- North Hills 31%
- San Francisco 31%
- Santa Clara 29%
- Los Angeles 29%
- Reseda 29%
- Hawthorne 28%
- Culver City 28%
- Studio City 28%
- Santa Monica 28%
- Winnetka 27%
- Irvine 27%
- Glendale 26%
- Walnut Creek 26%
- San Mateo 26%
- Pasadena 25%
- Coronado 24%
- Sunnyvale 23%
- Anaheim 23%
- Oakland 22%
- Signal Hill 22%
- Newport Beach 22%
- Belmont 22%
- Stanton 22%
- Torrance 22%
- Palo Alto 21%
- La Mesa 21%
- Tustin 21%
- San Diego 21%
- Chatsworth 21%
- National City 21%
- Burbank 21%
- Alameda 20%
- Bellflower 20%
- San Leandro 20%
- Aliso Viejo 20%
- Milpitas 19%
- Carmichael 19%
- Rohnert Park 19%
- El Cajon 19%
- Campbell 19%
- Brea 19%
- Fremont 18%
- San Ysidro 18%
- San Bruno 18%
- Berkeley 18%
- Paramount 18%
- Fullerton 18%
- San Jose 18%
- Long Beach 18%
- Dublin 18%
- Lomita 18%
- Sun Valley 17%
- Montrose 17%
- Goleta 17%
- Albany 17%
- Millbrae 17%
- Redondo Beach 17%
- Concord 17%
- Laguna Woods 17%
- Cupertino 16%
- Pleasant Hill 16%
- Santa Ana 16%
- Escondido 16%
- Larkspur 16%
- Daly City 16%
- Costa Mesa 16%
- Hayward 16%
- Burlingame 16%
- San Pablo 16%
- La Jolla 15%
- Santa Fe Springs 15%
- Davis 15%
- Colton 15%
- Solana Beach 15%
- San Marcos 15%
- El Monte 15%
- Montebello 15%
- Loma Linda 15%
- West Covina 15%
- San Pedro 15%
- Tujunga 15%
- Beverly Hills 15%
- Redwood City 15%
- Downey 15%
- Stevenson Ranch 15%
- La Habra 14%
- Inglewood 14%
- South San Francisco 14%
- Wilmington 14%
- Venice 14%
- Chula Vista 14%
- Rancho Cucamonga 14%
- Huntington Beach 14%
- Grand Terrace 14%
- San Rafael 14%
- La Palma 14%
- Newhall 14%
- Menlo Park 13%
- Orange 13%
- Gardena 13%
- Hermosa Beach 13%
- Monterey Park 13%
- Pleasanton 13%
- Del Mar 13%
- El Segundo 13%
- Sylmar 13%
- Garden Grove 13%
- Rancho Palos Verdes 13%
- Union City 13%
- San Bernardino 13%
- Greenbrae 13%
- Lemon Grove 13%
- Redlands 12%
- Upland 12%
- Westminster 12%
- Laguna Hills 12%
- Rancho Santa Margarita 12%
- San Gabriel 12%
- Monterey 12%
- Buena Park 12%
- Covina 12%
- Ontario 12%
- Alhambra 12%
- Porter Ranch 12%
- Norwalk 12%
- Placentia 11%
- Newport Coast 11%
- Lakeside 11%
- Port Hueneme 11%
- Hawaiian Gardens 11%
- Pico Rivera 11%
- Arcadia 11%
- Sacramento 11%
- South Pasadena 11%
- San Luis Obispo 11%
- Pomona 11%
- Harbor City 11%
- Duarte 11%
- Pacoima 11%
- Carpinteria 11%
- La Mirada 10%
- Rancho Cordova 10%
- Cypress 10%
- Pacific Grove 10%
- Valencia 10%
- Vista 10%
- Riverside 10%
- Monrovia 10%
- Palm Springs 10%
- Laguna Niguel 10%
- Ladera Ranch 10%
- Carlsbad 10%
- San Ramon 10%
- Chino 10%
- Montclair 10%
- Mission Hills 10%
- Chico 10%
- Granada Hills 10%
- Fontana 10%
- Santa Barbara 10%
- Napa 10%
- Azusa 10%
- Whittier 9%
- Lawndale 9%
- Rowland Heights 9%
- West Sacramento 9%
- Woodland 9%
- Camarillo 9%
- Seal Beach 9%
- Santa Cruz 9%
- Sausalito 9%
- Fresno 9%
- Yuba City 9%
- Novato 9%
- Petaluma 9%
- Huntington Park 9%
- Marysville 9%
- Spring Valley 9%
- Oxnard 9%
- Los Gatos 9%
- Sunland 9%
- Santee 9%
- Claremont 9%
- Fountain Valley 9%
- San Carlos 8%
- Oceanside 8%
- Baldwin Park 8%
- Willows 8%
- Thousand Oaks 8%
- Ventura 8%
- Pittsburg 8%
- Rialto 8%
- Santa Rosa 8%
- Richmond 8%
- Stockton 8%
- Castro Valley 8%
- La Crescenta 8%
- San Lorenzo 8%
- Encinitas 8%
- Newark 8%
- Fairfield 8%
- San Dimas 8%
- Roseville 8%
- Turlock 8%
- Lodi 8%
- Foothill Ranch 8%
- Carson 8%
- Marina 8%
- Los Alamitos 8%
- Watsonville 7%
- Vallejo 7%
- El Cerrito 7%
- Livermore 7%
- Dana Point 7%
- Folsom 7%
- Mentone 7%
- Imperial Beach 7%
- Lancaster 7%
- Saint Helena 7%
- Highland 7%
- Lafayette 7%
- Pacifica 7%
- Canyon Country 7%
- Palm Desert 7%
- Chino Hills 7%
- Salinas 7%
- Capitola 7%
- Rocklin 7%
- Citrus Heights 7%
- Poway 7%
- Pacific Palisades 7%
- Bell Gardens 7%
- Simi Valley 7%
- Antioch 7%
- Mission Viejo 7%
- American Canyon 7%
- Palmdale 7%
- Artesia 7%
- Fairfax 7%
- Malibu 7%
- Temecula 7%
- Hercules 7%
- Modesto 6%
- Glendora 6%
- San Clemente 6%
- Vacaville 6%
- Mira Loma 6%
- Santa Maria 6%
- Calabasas 6%
- Belvedere Tiburon 6%
- Lake Forest 6%
- Gilroy 6%
- Benicia 6%
- La Verne 6%
- Alpine 6%
- Lakewood 6%
- Suisun City 6%
- Corona 6%
- Pinole 6%
- Arcata 6%
- Cerritos 6%
- Hacienda Heights 6%
- Solvang 6%
- Hemet 6%
- Fallbrook 6%
- Clovis 6%
- El Sobrante 6%
- La Puente 6%
- Diamond Bar 6%
- Cotati 6%
- Agoura Hills 5%
- Los Altos 5%
- Laguna Beach 5%
- Cardiff by the Sea 5%
- Lynwood 5%
- Eastvale 5%
- Westlake Village 5%
- Orangevale 5%
- Manteca 5%
- Sierra Madre 5%
- Santa Clarita 5%
- Oakdale 5%
- Fillmore 5%
- Shingle Springs 5%
- Moreno Valley 5%
- Ceres 5%
- Jackson 5%
- Hughson 5%
- Martinez 5%
- South Gate 5%
- Corona del Mar 5%
- Elk Grove 5%
- Windsor 5%
- Antelope 5%
- Merced 5%
- Carmel 5%
- San Juan Capistrano 5%
- Ione 5%
- Jurupa Valley 4%
- Atascadero 4%
- Auburn 4%
- Ramona 4%
- Tracy 4%
- Rosemead 4%
- Wildomar 4%
- Maywood 4%
- Arroyo Grande 4%
- Compton 4%
- Murrieta 4%
- Seaside 4%
- Mill Valley 4%
- Corte Madera 4%
- Half Moon Bay 4%
- Fair Oaks 4%
- Morgan Hill 4%
- North Highlands 4%
- Victorville 4%
- Lompoc 4%
- Orinda 4%
- Bonita 4%
- Corning 4%
- Yorba Linda 4%
- Truckee 4%
- Saratoga 4%
- Cathedral City 4%
- Rancho Mirage 4%
- California City 4%
- Newbury Park 4%
- Dixon 4%
- San Fernando 4%
- Newman 4%
- Sonora 4%
- Livingston 4%
- Moraga 4%
- Indio 4%
- Hesperia 3%
- Banning 3%
- Palos Verdes Peninsula 3%
- Brentwood 3%
- Scotts Valley 3%
- San Anselmo 3%
- Eureka 3%
- South El Monte 3%
- South Lake Tahoe 3%
- Ripon 3%
- Riverbank 3%
- Moorpark 3%
- Oakley 3%
- Ojai 3%
- Sonoma 3%
- Delhi 3%
- Yucaipa 3%
- Danville 3%
- Perris 3%
- Santa Paula 3%
- Temple City 3%
- El Dorado Hills 3%
- Lake Elsinore 3%
- Oak Park 3%
- Placerville 2%
- Live Oak 2%
- Oroville 2%
- Walnut 2%
- Winchester 2%
- Paso Robles 2%
- Atwater 2%
- Desert Hot Springs 2%
- Red Bluff 2%
- Norco 2%
- Winters 2%
- Coachella 2%
- Altadena 2%
- Menifee 2%
- Galt 2%
- Healdsburg 2%
Before you call
A test is a scheduled job with a report at the end of it, not a repair. What the report has to show, and who it goes to, are on the pages above.
