Radium & Radionuclides
What is Radium & Radionuclides?
Radium and other radionuclides, including uranium and radon, are naturally radioactive elements that dissolve into groundwater from the rock and soil it passes through. Levels depend heavily on local geology and are highest in some wells and groundwater-fed systems.
Health effects
Long-term exposure to radium and other radionuclides in drinking water is associated with an increased risk of cancer, including bone cancer for radium. The EPA sets legal limits for combined radium-226/228 (5 pCi/L), uranium (30 µg/L), and gross alpha particles (15 pCi/L); health-based guidelines sit lower.
In DC-metro tap water
In our region, radionuclides are most associated with groundwater in the Shenandoah Valley's limestone karst and the coastal-plain aquifers, and with private wells. Surface-water systems drawing from the Potomac are generally lower risk for these specific contaminants.
How to remove it at the tap
Reverse osmosis reduces dissolved radionuclides such as radium and uranium at the point of use, and ion exchange (including some water softeners) also reduces radium. One caveat: radon is a gas and is best addressed by aeration rather than filtration. A multi-stage RO system handles the dissolved radionuclides that reach the tap.
Where Radium & Radionuclides shows up locally
Local water reports where this contaminant class is documented in the utility's data or watershed. Open your area to see the specifics and look up your exact zip code.
Frequently asked
How does radium get into drinking water?
It occurs naturally, dissolving from radioactive minerals in rock and soil into groundwater. That is why it is mainly a concern for wells and groundwater-fed systems rather than surface water.
Does reverse osmosis remove radium and uranium?
Yes, for the dissolved radionuclides that reach your tap. Radon, which is a gas, is the exception and is best handled by aeration rather than a filter.
Should I test my well for radionuclides?
Yes, especially if you are in a karst or coastal-plain area known for them. Private wells are not covered by municipal testing.
Related guides
The gap between what's legal and what's healthy
A utility can pass every federal test and still deliver water far above the levels health scientists consider safe. Federal legal limits were largely set decades ago; the health-based guidelines below reflect current cancer- and development-risk research.
Federal law allows 100× the health guideline
Sources: EPA National Primary Drinking Water Regulations (legal limits) and the EWG Tap Water Database / state public-health goals (health-based guidelines). A reverse osmosis system reduces every contaminant above at the point of use.