Are you worried that uranium or radon might be present in your well water because of nearby geology or mining activity?
How Do I Test My Well For Uranium Or Radon?
You should know that testing is the only reliable way to find out whether uranium or radon is in your well water. This section explains what to test for, how to arrange testing, and what results mean for your health and home.
Why you should test for uranium and radon
Both uranium and radon are naturally occurring radioactive elements that can enter groundwater from bedrock, mineral deposits, and human activities like mining. You may feel fine using your well every day, but chronic exposure — especially through drinking water and breathing radon released from water — can increase long-term health risks.
How nearby mining can affect your well water safety
Mining can expose and mobilize uranium and other radioactive elements by disturbing rock, generating acidic runoff, and creating new groundwater flow paths. If a mine or mineral processing site is near your well, your risk of contamination can be higher and you should test more often and for a broader suite of contaminants.
How uranium and radon behave in groundwater
Understanding how these contaminants move will help you prioritize testing and treatment.
Uranium in groundwater
Uranium is a heavy metal and a weakly radioactive element. It often occurs with other metals and is more mobile in groundwater under certain chemical conditions (e.g., oxidizing, high carbonate). When present in drinking water, uranium poses chemical toxicity to kidneys and a radiological risk over long-term exposures.
Radon in groundwater
Radon is a gas produced by uranium decay. Because it’s a gas, it can easily strip out of water into indoor air when you use showers, dishwashers, or run taps. The biggest health risk from waterborne radon is usually the radon that moves into your home’s indoor air and is inhaled, although ingested radon also carries some risk.
When should you test your well?
Testing at the right times improves your ability to detect problems early.
Initial and routine testing
You should test a new well before you begin using the water for drinking and cooking. After that, routine testing every 1–3 years is a good practice for radiological contaminants if you live in an area with elevated natural radioactivity or nearby mining. If conditions change — such as new mining activity, well repairs, or sudden changes in water taste, odor, or color — test immediately.
Testing after nearby mining or land changes
If mining begins nearby or an old mine is reactivated, test as soon as possible and continue testing frequently (for example, every 6–12 months) until you have confirmed your water is stable and safe. Mining can change groundwater flow and introduce contaminants that may appear months to years after mining activity starts.
What to test for (and why)
It’s smart to test for a range of contaminants that can co-occur with uranium or radon.
Minimum recommended tests
- Uranium (measure in micrograms per liter, µg/L)
- Radon in water (measure in picocuries per liter, pCi/L)
- Gross alpha and radium isotopes (gross alpha indicates alpha-emitting radionuclides)
- Other mining-related contaminants: arsenic, sulfate, iron, manganese, heavy metals, and nitrate
Testing for gross alpha and radium helps you understand the presence of other radioactive materials that often accompany uranium.
When you should ask for specialized tests
Ask your lab for specific radionuclide analyses if you suspect mining-related contamination: uranium-238/234, radium-226/228, and thorium isotopes. If your geological setting is complex, involve a hydrologist or environmental consultant to design a comprehensive testing plan.
How to choose a laboratory
Selecting the right lab ensures legally defensible and accurate results.
Look for certified laboratories
Use a state-certified drinking water laboratory or one accredited by the National Environmental Laboratory Accreditation Program (NELAP). Certification ensures the lab follows approved methods, has quality controls, and reports in correct units.
Confirm test methods and turnaround time
Ask the lab which analytical methods they use for uranium (commonly ICP-MS or EPA-approved radiochemical methods) and for radon in water (commonly liquid scintillation or degassing/emanation methods). Confirm sample container requirements, preservation methods, and how long results will take.
How to collect samples correctly
Proper sampling is critical for valid results, especially for radon and uranium.
General rules for sample collection
Always use the sample bottles provided by the lab, because they are cleaned and may be pre-preserved. Follow the lab’s instructions exactly — they will tell you how to flush the line, whether to collect from a tap or the wellhead, and whether to use cold water only. Label samples and keep them cool during transport.
Uranium sampling specifics
Uranium samples typically require preservation to prevent adsorption or precipitation. Many labs ask you to acidify the sample (with nitric acid) to a pH below 2; the lab will usually provide acid or instructions. Avoid metal fittings and containers that could contaminate the sample.
Radon-in-water sampling specifics
Radon is volatile, so radon samples must be collected with no headspace and handled gently to prevent gas loss. Labs supply special scintillation vials or glass bottles and will instruct you to fill them to the brim, cap carefully, and keep them cool. Deliver samples quickly — the shorter the time between sampling and analysis, the better the accuracy.
Interpreting results and regulatory limits
Knowing how to read numbers helps you decide what to do next.
Uranium guideline and health information
The U.S. Environmental Protection Agency (EPA) set a maximum contaminant level (MCL) for uranium in drinking water at 30 micrograms per liter (µg/L). If your test shows uranium above 30 µg/L, you should take action, such as stopping use for drinking and cooking until treatment is installed or an alternative supply is available.
Radon in water: no single federal limit
There is no federal MCL for radon in drinking water. State action levels and guidance vary. Because radon in water contributes to indoor air radon, many experts recommend treatment if water radon concentrations are high enough to elevate indoor air radon to levels of concern. Check your state health department for specific action levels and consult with a radon professional.
Typical result interpretation guidance
- Uranium: