Radium in Well Water: Limits, Testing and Results
Short answer: radium is a natural radioactive metal that can dissolve into groundwater. You can't see, smell or taste it, so only a lab test shows it. EPA's limit for public water is 5 pCi/L for radium-226 and radium-228 combined.
Official limits
| Item | US EPA (public water) | Health Canada |
|---|---|---|
| Radium-226 + radium-228 | 5 pCi/L combined | Ra-226: 5 Bq/L; Ra-228: 2 Bq/L |
| Gross alpha | 15 pCi/L (excluding radon and uranium) | Screening level 0.5 Bq/L |
pCi/L and Bq/L are different units: 1 pCi/L = 0.037 Bq/L. Use the lab report decoder to convert.
Where it occurs
Radium comes from the natural decay of uranium and thorium in rock. In New Jersey, the state health department notes elevated natural radioactivity in wells drawing from the southern Cohansey aquifer. State testing data from home sales show 36.3% of tested wells in Camden County and 30.6% in Cumberland County exceeded the 15 pCi/L gross alpha limit (2002–2024). See the New Jersey county pages.
How to test
Most labs start with a gross alpha screen (EPA method 900.0). If it is high, ask for radium-226 (EPA 903.0 or 903.1) and radium-228 (EPA 904.0). Use a lab certified for radiochemistry; many labs send these samples to a partner lab.
What results mean
- Below the limits: keep your record and retest as your state advises.
- Above: Health Canada lists ion exchange and reverse osmosis devices certified to remove radium. Retest the treated water.
Sources
- EPA: National Primary Drinking Water Regulations
- Health Canada: Guidelines for Canadian Drinking Water Quality, summary table (Dec 2025)
- EPA RadTown: Natural radionuclides in private wells
- NJDEP open data: PWTA summary results by county (2002–2024)
Questions
What is the EPA limit for radium in drinking water?
5 picocuries per liter (pCi/L) for radium-226 and radium-228 combined. It applies to public water systems; private wells are not regulated, but it is the common yardstick.
What is a gross alpha test?
A screening test for overall alpha radioactivity. EPA's limit is 15 pCi/L, not counting radon and uranium. A high result means you should test for radium and uranium individually.
Can a water softener remove radium?
Health Canada lists ion exchange and reverse osmosis devices certified for radium-226 and radium-228. Check the device's certification and retest after installing it.
Free well water checklist
15 family-friendly steps based on CDC and EPA guidance. Print it, keep it on the fridge, and know when to call a certified lab.
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- How Much Does Well Water Testing Cost? Real Lab PricesReal published prices from public labs, free programs, and the EPA-approved-lab myth.
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