Your county health department
Arizona doesn't run a statewide free testing program that we know of. Some county health departments test wells or sell kits, so call yours first.
Arizona's private well pageRadon in Arizona well water, by county
Radon is rare in tested Arizona wells: in all 13 counties with enough tests, fewer than 5% of tested wells were over the limit. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.
How Arizona compares with the rest of the country
Across Arizona, under 1 in 50 tested wells had radon in water over 4,000 pCi/L, a level the EPA proposed (10 of 748). Across all tested wells in the US it's about 1 in 24. That's less often than in the country as a whole. Counties still differ, so check yours below.
Why it matters: It escapes into the air when you shower or run the tap, and breathing it raises the risk of lung cancer.
Radon is a gas given off by uranium in granite and similar rock.
Radon in tested wells, county by county
Share of each county's tested wells with at least one result over 4,000 pCi/L, a level the EPA proposed. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.
| County | Wells tested | Wells over the limit | Level |
|---|---|---|---|
| Pima County | 48 | Rare | |
| Pinal County | 58 | Rare | |
| La Paz County | 90 | Rare | |
| Mohave County | 105 | Rare | |
| Cochise County | 75 | Rare | |
| Maricopa County | 106 | Rare | |
| Yavapai County | 85 | Rare | |
| Graham County | 60 | Rare | |
| Greenlee County | 22 | Rare | |
| Gila County | 21 | Rare | |
| Santa Cruz County | 21 | Rare | |
| Navajo County | 20 | Rare | |
| Yuma County | 20 | Rare |
2 more Arizona counties have 1 to 9 tested wells for radon in water, too few to rate.
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Where to get your well tested for radon in water in Arizona
A lab Arizona certifies
Ask for radon in water by name. Results from a certified lab count for a home sale or a loan.
Labs certified by ArizonaA mail-in kit
Fill the bottles at your kitchen tap and mail them back. We mark the kits that include radon in water.
Compare kitsKeep reading about wells in Arizona
- Well water testing in Arizona: how to get tested and what turns up statewide
- Radon in well water: where it comes from, what it does and how to remove it
- Nitrate in Arizona wells, by county
- Arsenic in Arizona wells, by county
- Uranium in Arizona wells, by county
- Manganese in Arizona wells, by county
- Lead in Arizona wells, by county
Questions people ask about radon in water in Arizona
Is there radon in water in Arizona well water?
Radon is rare in tested Arizona wells: in all 13 counties with enough tests, fewer than 5% of tested wells were over the limit. Across Arizona, under 1 in 50 tested wells had radon in water over 4,000 pCi/L, a level the EPA proposed (10 of 748). Across all tested wells in the US it's about 1 in 24. That's less often than in the country as a whole. Counties still differ, so check yours below.
Where can I get my well tested for radon in water in Arizona?
Use a lab certified by Arizona for drinking water, or a mail-in kit that includes radon in water from a certified lab. Some county health departments test wells too, so call yours first.
See Arizona's list of certified labs, or compare mail-in kits.
Where these numbers come from
- Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over 4,000 pCi/L, a level the EPA proposed. Wells tested for studies and monitoring, not a random sample of homes.
- Likely overstated: our own check of who tested the wells, when and where. How we check.
- State programs and links: Department of Health Services.