Nitrate Water Testing Labs in California (118 state-certified labs)
Labs on California's official certification list that test drinking water for nitrate, with the ones that take homeowner samples first.
Labs certified for nitrate118
118 named for nitrate itself on the list.
Marked as taking public samples61
Per the state list or a state web page. Call to confirm.
Out-of-state labs15
Located outside California but on its list.
People on private wells (2015)1,435,510
USGS estimate for California.
How many labs test for nitrate in California
118 labs on California's official drinking-water lab list are certified to test for nitrate. All 118 are named for nitrate on the list. 61 of them are marked as taking samples from the public. They are listed first. 15 are located outside California.
The list is published by the California State Water Resources Control Board - Environmental Laboratory Accreditation Program (ELAP). These labs come from list files with 87 different dates; each lab page shows its own. Fetched 2026-11-15 (UTC).
California labs certified for nitrate
Marked as taking public samples (61)
| Lab | Location | Nitrate certification | Public samples | Cert. expiry |
|---|---|---|---|---|
| 49er Water Laboratory | Jackson, CA | Named on the official list | Public samples: yes (per state) | 12/31/2027 |
| AIH Laboratory, Inc. | Anaheim, CA | Named on the official list | Public samples: yes (per state) | 6/30/2028 |
| Alpha Analytical Laboratories Inc. - North Bay | Petaluma, CA | Named on the official list | Public samples: yes (per state) | 3/31/2028 |
| Alpha Analytical Laboratories, Inc. | Elk Grove, CA | Named on the official list | Public samples: yes (per state) | 6/30/2028 |
| Alpha Analytical Laboratories, Inc. - Los Angeles | Signal Hill, CA | Named on the official list | Public samples: yes (per state) | 1/9/2027 |
| Alpha Analytical Laboratories, Inc. - San Diego | Vista, CA | Named on the official list | Public samples: yes (per state) | 3/16/2028 |
| Alpha Analytical Laboratories, Inc. - Ukiah | Ukiah, CA | Named on the official list | Public samples: yes (per state) | 6/30/2027 |
| ALS Environmental - Kelso | Kelso, WA | Named on the official list | Public samples: yes (per state) | 2/10/2027 |
| American Water Central Laboratory | Belleville, IL | Named on the official list | Public samples: yes (per state) | 10/31/2027 |
| Analytical Environmental Lab, LLC | San Diego, CA | Named on the official list | Public samples: yes (per state) | 8/30/2027 |
| Applied Industrial Microbiology, Inc. | Vista, CA | Named on the official list | Public samples: yes (per state) | 1/31/2027 |
| ASSET Laboratories | Las Vegas, NV | Named on the official list | Public samples: yes (per state) | 1/29/2027 |
| Babcock Laboratories, Inc. | Riverside, CA | Named on the official list | Public samples: yes (per state) | 5/31/2028 |
| Bracewell Engineering, Inc. | Morgan Hill, CA | Named on the official list | Public samples: yes (per state) | 2/18/2028 |
| Brelje and Race Laboratories, Inc. | Santa Rosa, CA | Named on the official list | Public samples: yes (per state) | 7/31/2028 |
| BSK Associates | Fresno, CA | Named on the official list | Public samples: yes (per state) | 4/30/2028 |
| California Laboratory Services | Rancho Cordova, CA | Named on the official list | Public samples: yes (per state) | 6/30/2028 |
| Caltest Analytical Laboratory | Napa, CA | Named on the official list | Public samples: yes (per state) | 11/30/2027 |
| Capco Analytical Services | Ventura, CA | Named on the official list | Public samples: yes (per state) | 3/31/2027 |
| Clinical Laboratory of San Bernardino, Inc. | Grand Terrace, CA | Named on the official list | Public samples: yes (per state) | 1/31/2028 |
| Continental Water Laboratory | Sacramento, CA | Named on the official list | Public samples: yes (per state) | 1/31/2028 |
| Cranmer Engineering, Inc. | Grass Valley, CA | Named on the official list | Public samples: yes (per state) | 8/31/2027 |
| Culligan Analytical Laboratory | Rosemont, IL | Named on the official list | Public samples: yes (per state) | 11/30/2026 |
| Dellavalle Laboratory, Inc. | Fresno, CA | Named on the official list | Public samples: yes (per state) | 8/31/2027 |
| EMAX Laboratories, Inc. | Torrance, CA | Named on the official list | Public samples: yes (per state) | 12/14/2027 |
| EMSL Analytical Inc. | Cinnaminson, NJ | Named on the official list | Public samples: yes (per state) | 6/30/2027 |
| EMSL Analytical, Inc. | Saint Louis, MO | Named on the official list | Public samples: yes (per state) | 2/26/2027 |
| Environmental Laboratory Network, Inc. | San Diego, CA | Named on the official list | Public samples: yes (per state) | 3/31/2027 |
| Eurofins Lancaster Laboratories Environment Testing, LLC | Lancaster, PA | Named on the official list | Public samples: yes (per state) | 1/31/2026 Date on list has passed |
| Eurofins Pomona | Pomona, CA | Named on the official list | Public samples: yes (per state) | 6/18/2027 |
| Eurofins South Bend | South Bend, IN | Named on the official list | Public samples: yes (per state) | 6/30/2027 |
| Fruit Growers Laboratory, Inc. | Santa Paula, CA | Named on the official list | Public samples: yes (per state) | 7/31/2027 |
| Garratt-Callahan Laboratory | Burlingame, CA | Named on the official list | Public samples: yes (per state) | 3/17/2027 |
| GEL Laboratories, LLC | Charleston, SC | Named on the official list | Public samples: yes (per state) | 10/31/2026 Date on list has passed |
| Institute of Environmental Health, Inc. dba IEH-JL Analytical | Modesto, CA | Named on the official list | Public samples: yes (per state) | 12/9/2027 |
| K Prime, LLC. | Santa Rosa, CA | Named on the official list | Public samples: yes (per state) | 5/31/2027 |
| Lodi Wine Laboratories | Lodi, CA | Named on the official list | Public samples: yes (per state) | 4/23/2028 |
| McCampbell Analytical, Inc. | Pittsburg, CA | Named on the official list | Public samples: yes (per state) | 11/2/2027 |
| Michelson Laboratories, Inc. | Commerce, CA | Named on the official list | Public samples: yes (per state) | 5/31/2028 |
| Microbac Laboratories, Inc. - Arcata | Arcata, CA | Named on the official list | Public samples: yes (per state) | 7/31/2028 |
| Microbac Laboratories, Inc. - Turlock | Turlock, CA | Named on the official list | Public samples: yes (per state) | 3/31/2028 |
| Monterey Bay Analytical Services, Inc. | Monterey, CA | Named on the official list | Public samples: yes (per state) | 10/31/2027 |
| Monterey County Consolidated Environmental Laboratory | Salinas, CA | Named on the official list | Public samples: yes (per state) | 12/31/2026 |
| Moore Twining Associates, Inc. | Fresno, CA | Named on the official list | Public samples: yes (per state) | 9/30/2028 |
| National Testing Laboratories, Ltd | Ypsilanti, MI | Named on the official list | Public samples: yes (per state) | 6/30/2027 |
| Oilfield Environmental & Compliance Inc. (OEC) | Santa Maria, CA | Named on the official list | Public samples: yes (per state) | 10/31/2028 |
| Onterris Laboratories, LLC | Orange, CA | Named on the official list | Public samples: yes (per state) | 10/31/2028 |
| Pace Analytical National Center for Testing & Innovation | Mount Juliet, TN | Named on the official list | Public samples: yes (per state) | 6/30/2027 |
| Pace Analytical Services, LLC | Minneapolis, MN | Named on the official list | Public samples: yes (per state) | 12/31/2026 |
| Pace Analytical Services, LLC dba BC Laboratories, Inc. | Bakersfield, CA | Named on the official list | Public samples: yes (per state) | 5/31/2028 |
| Pat-Chem Laboratories | San Fernando, CA | Named on the official list | Public samples: yes (per state) | 5/31/2027 |
| Positive Lab Service | Los Angeles, CA | Named on the official list | Public samples: yes (per state) | 2/28/2028 |
| SGS North America, Inc. | Clovis, CA | Named on the official list | Public samples: yes (per state) | 9/30/2028 |
| SGS Silver State Analytical Lab - Reno | Reno, NV | Named on the official list | Public samples: yes (per state) | 3/13/2027 |
| Sierra Analytical Labs, Inc. | Laguna Hills, CA | Named on the official list | Public samples: yes (per state) | 10/31/2028 |
| Sparger Technology, Inc. | Sacramento, CA | Named on the official list | Public samples: yes (per state) | 3/27/2027 |
| Spring Street Analytical | Klamath Falls, OR | Named on the official list | Public samples: yes (per state) | 6/22/2027 |
| Torrent Laboratory, Inc | Milpitas, CA | Named on the official list | Public samples: yes (per state) | 4/30/2028 |
| Weck Laboratories, Inc. | City of Industry, CA | Named on the official list | Public samples: yes (per state) | 3/31/2028 |
| Western Environmental Testing Laboratory | Sparks, NV | Named on the official list | Public samples: yes (per state) | 6/30/2026 Date on list has passed |
| Zalco Laboratories, Inc. | Bakersfield, CA | Named on the official list | Public samples: yes (per state) | 7/31/2027 |
Other labs on the list (57)
| Lab | Location | Nitrate certification | Public samples | Cert. expiry |
|---|---|---|---|---|
| Alameda County Water District Water Quality Laboratory | Fremont, CA | Named on the official list | Public samples: ask the lab | 5/31/2027 |
| BSK Associates - Sacramento Analytical Laboratory | Sacramento, CA | Named on the official list | Public samples: ask the lab | 4/30/2028 |
| California Water Service Company WQ Laboratory | San Jose, CA | Named on the official list | Public samples: ask the lab | 9/30/2028 |
| Camrosa Water District Laboratory | Camarillo, CA | Named on the official list | Public samples: ask the lab | 9/30/2027 |
| Coachella Valley Water District | Palm Desert, CA | Named on the official list | Public samples: ask the lab | 7/31/2028 |
| Contra Costa Water District Laboratory | Concord, CA | Named on the official list | Public samples: ask the lab | 6/30/2027 |
| Dublin San Ramon Services District | Pleasanton, CA | Named on the official list | Public samples: ask the lab | 8/31/2028 |
| E & J Gallo Winery | Modesto, CA | Named on the official list | Public samples: ask the lab | 9/30/2027 |
| E.V.M.W.D. Regional Laboratory | Lake Elsinore, CA | Named on the official list | Public samples: ask the lab | 10/31/2028 |
| Escondido - City Water Quality Laboratory | Escondido, CA | Named on the official list | Public samples: ask the lab | 9/30/2027 |
| Eurofins Sacramento Service Center | West Sacramento, CA | Named on the official list | Public samples: ask the lab | 6/18/2027 |
| Irvine Ranch Water District | Irvine, CA | Named on the official list | Public samples: ask the lab | 1/31/2028 |
| Kern County Water Agency | Bakersfield, CA | Named on the official list | Public samples: ask the lab | 12/31/2027 |
| Laguna Environmental Laboratory | Santa Rosa, CA | Named on the official list | Public samples: ask the lab | 2/28/2026 Date on list has passed |
| Monterey One Water (M1W) | Marina, CA | Named on the official list | Public samples: ask the lab | 5/31/2028 |
| North Marin Water District - RCP Lab | Novato, CA | Named on the official list | Public samples: ask the lab | 7/31/2027 |
| Orange County Water District Laboratory | Fountain Valley, CA | Named on the official list | Public samples: ask the lab | 2/28/2028 |
| Padre Dam Water Recycling Laboratory | Santee, CA | Named on the official list | Public samples: ask the lab | 11/30/2027 |
| Palmdale Water District | Palmdale, CA | Named on the official list | Public samples: ask the lab | 7/31/2028 |
| SacSewer Environmental Laboratory | Elk Grove, CA | Named on the official list | Public samples: ask the lab | 1/31/2028 |
| San Luis Obispo County Water Quality Laboratory | San Luis Obispo, CA | Named on the official list | Public samples: ask the lab | 8/31/2027 |
| Santa Clara Valley Water District | San Jose, CA | Named on the official list | Public samples: ask the lab | 5/31/2028 |
| Santa Clarita Valley Water Agency Laboratory | Santa Clarita, CA | Named on the official list | Public samples: ask the lab | 9/30/2027 |
| Santa Margarita Water District Laboratory | Rancho Mission Viejo, CA | Named on the official list | Public samples: ask the lab | 7/31/2027 |
| SFPUC Millbrae Laboratory | Millbrae, CA | Named on the official list | Public samples: ask the lab | 2/28/2027 |
| Sweetwater Authority | Spring Valley, CA | Named on the official list | Public samples: ask the lab | 12/31/2026 |
| West Basin Water Quality Laboratory | El Segundo, CA | Named on the official list | Public samples: ask the lab | 1/31/2028 |
| Zone 7 Water Quality Laboratory | Livermore, CA | Named on the official list | Public samples: ask the lab | 12/31/2026 |
| City of Beverly Hills Water Quality Laboratory | Beverly Hills, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 8/31/2027 |
| City of Brentwood Water Quality Laboratory | Brentwood, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 6/30/2027 |
| City of Fresno Wastewater Management Division Laboratory | Fresno, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 8/31/2028 |
| City of Hayward WPCF Laboratory | Hayward, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 3/31/2028 |
| City of Los Angeles Dept. of Water & Power, Water Quality Laboratory | Pasadena, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 9/30/2028 |
| City of Manteca WQCF Laboratory | Manteca, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 1/31/2028 |
| City of Modesto Water Quality Control Laboratory | Modesto, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 10/31/2028 |
| City of Napa Jamieson Canyon Water Treatment Plant | American Canyon, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 3/31/2028 |
| City of Oceanside Water Utilities Laboratory | Oceanside, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 4/30/2028 |
| City of Pasadena Water Quality Laboratory | Pasadena, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 3/31/2025 Date on list has passed |
| City of Porterville Laboratory | Porterville, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 10/31/2027 |
| City of Redlands Joint Utilities Laboratory | Redlands, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 5/31/2027 |
| City of Sacramento, Water Quality Laboratory | Sacramento, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 5/31/2027 |
| City of San Buenaventura Laboratory | Ventura, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 5/31/2028 |
| City of San Diego Water Quality Laboratory | La Mesa, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 11/30/2027 |
| City of Santa Cruz Water Quality Laboratory | Santa Cruz, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 4/30/2027 |
| City of Santa Monica/Water Quality Laboratory | Los Angeles, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 3/31/2027 |
| City of Sunnyvale Environmental Laboratory | Sunnyvale, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 10/31/2026 Date on list has passed |
| City of Tracy - Utilities Department Laboratory | Tracy, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 3/31/2027 |
| City of Watsonville Utilities Department Laboratory | Watsonville, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 4/30/2027 |
| City of Yuba City Water/Wastewater Laboratory | Yuba City, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 7/31/2028 |
| East Bay Municipal Utility District | Oakland, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 12/31/2027 |
| Eastern Municipal Water District | Perris, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 11/30/2026 |
| Inland Empire Utilities Agency - Laboratory | Chino, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 10/31/2028 |
| Las Virgenes Municipal Water District Laboratory | Calabasas, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 5/31/2027 |
| Long Beach Utilities Water Quality Laboratory | Long Beach, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 2/28/2029 |
| Metropolitan Water District - La Verne Water Quality Laboratory | La Verne, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 10/31/2027 |
| South Tahoe Public Utility District | South Lake Tahoe, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 7/31/2027 |
| Water Resources Laboratory | Santa Barbara, CA | Named on the official list | Public samples: ask the lab Looks like a utility or municipal lab, judging by the name (our label, not the state list) | 4/30/2027 |
How the California list marks public samples (whole list). ELAP's map layer gives each lab a type. Labs of type 'Commercial' take commercial samples; that is broader than 'homeowner', so call before you send a sample. Other lab types (city, water district, wastewater, industrial ...) are not marked either way.
Before you send a sample, call the lab to confirm it is currently certified for the exact test and method, that it accepts samples from homeowners, and how to collect and ship them. Status can change between list updates.
Why test for nitrate in California
Nitrate has no taste or smell, and a lab report can state the same water in two units that differ by a factor of 4.43. Read our nitrate explainer.
EPA advises private-well owners to test every year for total coliform bacteria, nitrates, total dissolved solids and pH. [1]
California guidance that mentions nitrate:
- The State Water Board's well-owner guide recommends testing once a year. At a minimum: total coliform bacteria, nitrate and electrical conductivity every year. A minerals panel (arsenic, lead, manganese, iron and other metals) every 5 to 10 years, or sooner if conductivity, taste, color, odor or nearby land use changes. [2]
- The state does not regulate water quality in most private domestic wells, but counties or local agencies may have their own rules. For example, some wells on farmland may have to be tested for nitrate. Local environmental health agencies may help you read your results. [2]
About 1,435,510 people in California used private wells in 2015, by the USGS estimate of people on domestic self-supplied water. [3] Federal limits are written for public water systems, not private wells, so testing is up to the owner.
For tests that depend on your home (farms nearby, old plumbing, a new baby), use the which-tests checklist. When results arrive, check your numbers against EPA's limits. State guidance, county data and every lab: California.
Other tests in California
Bacteria testing247 labsArsenic testing78 labsLead testing85 labsPFAS testing32 labsUranium testing32 labsRadon in water testing7 labsManganese testing85 labsVOC testing50 labs
Sources
- U.S. EPA, Protect your home's water
- California State Water Resources Control Board, GAMA Program, A Guide for Private Domestic Well Owners (June 2025)
- USGS, Estimated use of water in the United States, county-level data for 2015 (Dieter et al., ver. 2.0, 2018)
- California ELAP - Accredited Laboratories (map layer) + per-lab Fields of Accreditation (official list)
Certified as ofVaries by lab
California ELAP - Accredited Laboratories (map layer) + per-lab Fields of Accreditation.
Official source