Radon in Water Testing Labs in California (7 state-certified labs)
Labs on California's official certification list that test drinking water for radon in water, with the ones that take homeowner samples first.
7 named for radon in water itself on the list.
Per the state list or a state web page. Call to confirm.
Located outside California but on its list.
USGS estimate for California.
How many labs test for radon in water in California
7 labs on California's official drinking-water lab list are certified to test for radon in water. All 7 are named for radon in water on the list. 7 of them are marked as taking samples from the public. They are listed first. 5 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 7 different dates; each lab page shows its own. Fetched 2026-11-15 (UTC).
California labs certified for radon in water
Marked as taking public samples (7)
| Lab | Location | Radon in water certification | Public samples | Cert. expiry |
|---|---|---|---|---|
| EMSL Analytical Inc. | Cinnaminson, NJ | Named on the official list | Public samples: yes (per state) | 6/30/2027 |
| 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 |
| Eurofins St. Louis | Earth City, MO | 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 |
| Pace Analytical Services, LLC-Greensburg, PA | Greensburg, PA | Named on the official list | Public samples: yes (per state) | 3/31/2027 |
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 radon in water in California
Most of the risk from radon in a well comes from breathing the gas the water releases indoors, not from drinking it. Read our radon in water explainer.
EPA's radon zone map puts 2 of California's 58 counties in Zone 1 (highest potential), 29 in Zone 2 and 27 in Zone 3. [1] That map is about radon in indoor air, and EPA says it should not be used to decide whether an individual home needs testing. If radon is found in your air and you have a well, EPA suggests testing the water too.
About 1,435,510 people in California used private wells in 2015, by the USGS estimate of people on domestic self-supplied water. [2] 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
California ELAP - Accredited Laboratories (map layer) + per-lab Fields of Accreditation.
Official sourceSearch by city or ZIP among labs for radon in water.
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