Arsenic Water Testing Labs in California (78 state-certified labs)
Labs on California's official certification list that test drinking water for arsenic, with the ones that take homeowner samples first.
Labs certified for arsenic78
78 named for arsenic itself on the list.
Marked as taking public samples54
Per the state list or a state web page. Call to confirm.
Out-of-state labs17
Located outside California but on its list.
People on private wells (2015)1,435,510
USGS estimate for California.
How many labs test for arsenic in California
78 labs on California's official drinking-water lab list are certified to test for arsenic. All 78 are named for arsenic on the list. 54 of them are marked as taking samples from the public. They are listed first. 17 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 57 different dates; each lab page shows its own. Fetched 2026-11-15 (UTC).
California labs certified for arsenic
Marked as taking public samples (54)
| Lab | Location | Arsenic certification | Public samples | Cert. expiry |
|---|---|---|---|---|
| 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. - 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 |
| 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 |
| 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 |
| 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 |
| EMSL Analytical Inc. | Cinnaminson, NJ | Named on the official list | Public samples: yes (per state) | 6/30/2027 |
| EMSL Analytical, Inc. | Indianapolis, IN | 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 Hazards Services LLC | North Chesterfield, VA | Named on the official list | Public samples: yes (per state) | 9/30/2026 Date on list has passed |
| 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 |
| GEL Laboratories, LLC | Charleston, SC | Named on the official list | Public samples: yes (per state) | 10/31/2026 Date on list has passed |
| JK BioScience Inc. | Rancho Dominguez, CA | Named on the official list | Public samples: yes (per state) | 8/31/2027 |
| K Prime, LLC. | Santa Rosa, CA | Named on the official list | Public samples: yes (per state) | 5/31/2027 |
| LA Testing | Huntington Beach, CA | Named on the official list | Public samples: yes (per state) | 1/31/2028 |
| 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 |
| Precision Enviro-Tech | Stockton, CA | Named on the official list | Public samples: yes (per state) | 8/31/2028 |
| Schneider Laboratories Global, Inc. | Richmond, VA | Named on the official list | Public samples: yes (per state) | 3/14/2027 |
| SGS Built Environment | Carson, CA | Named on the official list | Public samples: yes (per state) | 10/31/2028 |
| 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 |
| 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 |
Other labs on the list (24)
| Lab | Location | Arsenic 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 |
| California Water Service Company WQ Laboratory | San Jose, CA | Named on the official list | Public samples: ask the lab | 9/30/2028 |
| Coachella Valley Water District | Palm Desert, CA | Named on the official list | Public samples: ask the lab | 7/31/2028 |
| 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 |
| Orange County Water District Laboratory | Fountain Valley, CA | Named on the official list | Public samples: ask the lab | 2/28/2028 |
| SacSewer Environmental Laboratory | Elk Grove, CA | Named on the official list | Public samples: ask the lab | 1/31/2028 |
| 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 |
| SFPUC Southeast Laboratory | San Francisco, CA | Named on the official list | Public samples: ask the lab | 2/28/2028 |
| Zone 7 Water Quality Laboratory | Livermore, CA | Named on the official list | Public samples: ask the lab | 12/31/2026 |
| 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 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 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 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 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 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 |
| 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 |
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 arsenic in California
Arsenic is invisible, tasteless and mostly natural, and it comes in two forms that respond very differently to treatment. Read our arsenic explainer.
California guidance that mentions arsenic:
- 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. [1]
USGS estimates that the most private-well users with arsenic above 10 µg/L, EPA's limit for public water, live in Los Angeles County, San Joaquin County and Fresno County (about 17,244 people in Los Angeles County, 2010 base year). USGS describes this kind of estimate as useful "for broad screening of the population at risk", so it says nothing certain about any one well. [2]
Show the numbers
| Item | Value | Note |
|---|---|---|
| Los Angeles County | 17,244 people (2010 base year) | |
| San Joaquin County | 9,497 people (2010 base year) | |
| Fresno County | 8,027 people (2010 base year) | |
| Merced County | 7,499 people (2010 base year) | |
| San Diego County | 6,352 people (2010 base year) | |
| Tulare County | 5,344 people (2010 base year) |
USGS model estimate for broad screening, not a measurement of any well. Only a test tells you about your own well. Source: USGS, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter (Ayotte, Medalie and Qi, 2017), accessed 2026-11-01.
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 labsNitrate testing118 labsLead testing85 labsPFAS testing32 labsUranium testing32 labsRadon in water testing7 labsManganese testing85 labsVOC testing50 labs
Sources
- California State Water Resources Control Board, GAMA Program, A Guide for Private Domestic Well Owners (June 2025)
- USGS, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter (Ayotte, Medalie and Qi, 2017)
- 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