Radium in Drinking Water

Data source: U.S. EPA

ZipCheckup tracks Radium in U.S. drinking water against the EPA limit of 5 pCi/L (combined Ra-226 + Ra-228) under the Radionuclides Rule. Radium carries a high health-risk designation.

What Is Radium in Drinking Water?

Radium is a naturally occurring radioactive element found in rock and soil. It enters drinking water when groundwater dissolves radium-bearing minerals. Radium-226 and Radium-228 are the isotopes most commonly found in water. Because radium behaves chemically like calcium, the body absorbs it and deposits it in bones.

Health Effects

• Bone cancer — radium accumulates in bones, increasing cancer risk with long-term exposure
• At 5 pCi/L over a lifetime: estimated 1 in 10,000 excess cancer risk
• Other cancers: some evidence of increased risk for leukemia
• No safe threshold for radioactive exposure — risk is proportional to dose

EPA Standards

• MCL: 5 pCi/L for combined Radium-226 and Radium-228
• Gross Alpha MCL: 15 pCi/L (screening test that captures radium and other alpha emitters)
• Radium violations are among the most common radioactivity violations in U.S. water systems

How to Remove Radium

• Ion exchange (water softener) — effective for radium removal
• Reverse osmosis — removes 90%+ of radium
• Lime softening — used at municipal scale
• Standard carbon filters do NOT remove radium