Radium is a naturally occurring radioactive element that can be found in groundwater, particularly in areas where certain rocks and soils contain naturally occurring radioactive materials. Although radium is usually present at very low levels, elevated concentrations in drinking water can pose long-term health risks and require treatment.
Unlike contaminants that primarily affect taste, odor, or appearance, radium is a radiological contaminant. Because it emits ionizing radiation, prolonged exposure above regulatory limits can increase the risk of certain health effects, including cancer. EPA regulates radium in public drinking water supplies and has established enforceable standards for radium levels in drinking water. (US EPA)
This guide explains what radium is, potential health risks, EPA guidelines, testing methods, filtration options, and recommended treatment technologies.
For a complete overview of drinking-water contaminants, visit RevOsmo’s Drinking Water Contaminants Explained pillar page:
What Is Radium?
Radium is a naturally occurring radioactive metal formed through the decay of uranium and thorium in rocks and soil. Because radium can dissolve into groundwater, it may be present in private wells and some public water systems.
The two most significant forms found in drinking water are:
- Radium-226 (Ra-226)
- Radium-228 (Ra-228)
These radioactive isotopes emit radiation as they decay. EPA specifically regulates the combined concentration of radium-226 and radium-228 in drinking water. (US EPA)
Where Does Radium in Drinking Water Come From?
Radium enters drinking water primarily through natural geological processes.
Common sources include:
Natural Rock and Soil Deposits
As groundwater moves through rocks and soil containing naturally occurring radioactive materials, small amounts of radium can dissolve into the water. (US EPA)
Groundwater Aquifers
Private wells drawing from deep groundwater formations are more likely to encounter elevated radium levels than surface-water sources. (US EPA)
Uranium-Bearing Geology
Areas with naturally occurring uranium deposits often have a greater potential for radium contamination because radium forms during uranium decay. (US EPA)
Certain Industrial Activities
Mining and processing activities involving radioactive minerals can contribute to environmental releases, although natural geology remains the most common source in drinking water. (US EPA)
Health Risks of Radium in Drinking Water
The primary concern with radium is its radioactivity.
When consumed in drinking water over many years, radium can accumulate in the body, particularly in bones, because the body may treat radium similarly to calcium.
EPA identifies increased cancer risk as the primary health concern associated with long-term exposure to radium above regulatory limits. (US EPA)
Potential Health Effects
Long-term exposure may increase the risk of:
- Bone cancer
- Liver cancer
- Breast cancer
- Other radiation-related cancers
EPA notes that chronic exposure to elevated radium levels can increase cancer incidence. (US EPA)
Why Radium Is Different
Unlike contaminants such as chlorine or sulfur that often produce noticeable taste or odor changes, radium:
- Has no taste
- Has no odor
- Is invisible
- Cannot be detected without testing
Many homeowners discover radium only after laboratory analysis.
EPA Guidelines for Radium in Drinking Water
EPA regulates radium under the National Primary Drinking Water Regulations.
Maximum Contaminant Level (MCL)
The federal drinking-water standard for:
Combined Radium-226 and Radium-228 = 5 pCi/L
(pCi/L = picocuries per liter)
This limit applies to the combined total of radium-226 and radium-228. (US EPA)
Maximum Contaminant Level Goal (MCLG)
EPA’s health-based goal for combined radium is:
0 pCi/L
Because radium is radioactive and associated with cancer risk, EPA established a health goal of zero. (US EPA)
Source of Radium
EPA identifies the primary source as:
Erosion of natural radioactive mineral deposits. (US EPA)
How to Test for Radium in Drinking Water
Because radium cannot be seen, smelled, or tasted, testing is essential.
1. Review Your Water Quality Report
If you receive water from a public utility, review the annual Consumer Confidence Report (CCR).
Public water systems are required to monitor radionuclides and comply with federal standards. (US EPA)
2. Test Private Well Water
Private wells are not regulated by EPA.
If you use a private well, consider testing if:
- You live in an area known for radionuclides
- Nearby wells have elevated radium
- Groundwater contains uranium
- You’re purchasing a home with a well
EPA notes that private wells are not regulated under the federal drinking-water standards. (US EPA)
3. Use a Certified Laboratory
Radium testing requires specialized laboratory analysis.
Common tests include:
- Radium-226
- Radium-228
- Gross alpha radiation
- Uranium
- Radon (optional depending on local conditions)
EPA has approved multiple analytical methods specifically for measuring radium in drinking water. (US EPA)
4. Test for Other Radionuclides
If radium is present, consider testing for:
- Uranium
- Radon
- Gross alpha activity
These contaminants frequently occur in the same geological environments. (US EPA)
Best Filtration Methods for Radium Removal
Several treatment technologies can effectively reduce radium.
EPA identifies the following as best available treatment technologies for radium removal. (EPA NEPIS)
1. Ion Exchange
Ion exchange is one of the most common methods used to remove radium.
The process works similarly to water softening by exchanging ions in the water for ions attached to treatment media.
Advantages
- Highly effective for radium
- Proven treatment technology
- Available for whole-house applications
- Can also reduce hardness
Disadvantages
- Requires maintenance
- Produces waste brine
- Media eventually requires replacement
EPA lists ion exchange as a best available technology for radium treatment. (EPA NEPIS)
2. Reverse Osmosis
Reverse osmosis (RO) can effectively reduce many dissolved contaminants, including radionuclides.
RO uses a semi-permeable membrane that blocks many dissolved substances from passing through.
Advantages
- Effective for drinking water treatment
- Reduces many contaminants simultaneously
- Suitable for under-sink installations
- Broad-spectrum filtration
Disadvantages
- Treats only point-of-use water
- Produces wastewater
- Requires periodic membrane replacement
EPA identifies reverse osmosis as a best available treatment technology for combined radium-226 and radium-228. (EPA NEPIS)
If you’re considering RO, see RevOsmo’s:
Best Reverse Osmosis Systems
https://revosmo.com/best-reverse-osmosis-systems-for-home/
3. Lime Softening
Large municipal systems often use lime softening to reduce radium concentrations.
This process raises water pH and promotes precipitation of certain contaminants.
Advantages
- Effective at larger scale
- Can reduce multiple contaminants
- Used by public utilities
Disadvantages
- Typically not practical for most homeowners
- Requires specialized equipment
EPA identifies lime softening as a best available technology for radium removal. (EPA NEPIS)
4. Under-Sink Filtration Systems
For homeowners focused on drinking and cooking water, an under-sink system may provide a practical solution.
Systems utilizing reverse osmosis technology are often selected because they can address multiple dissolved contaminants simultaneously.
Learn more in RevOsmo’s:
Best Under Sink Water Filters
https://revosmo.com/best-under-sink-water-filters/
Recommended Products for Radium Removal
The best solution depends on whether you’re treating:
- Entire household water
- Drinking water only
- Multiple contaminants
Best Whole-House Solution
Ion exchange systems
Often selected when radium affects all household water.
Best Drinking Water Solution
Reverse osmosis systems
Provide point-of-use treatment for drinking and cooking water while reducing numerous dissolved contaminants.
Best Multi-Contaminant Solution
If testing reveals:
- Radium
- Uranium
- Nitrate
- Arsenic
- High TDS
A reverse osmosis system may provide broad-spectrum treatment.
Compare available options in RevOsmo’s:
Water Filter Reviews
https://revosmo.com/water-filter-reviews/
Does Reverse Osmosis Remove Radium?
Yes.
EPA specifically identifies reverse osmosis as a best available technology for removing combined radium-226 and radium-228 from drinking water. (EPA NEPIS)
However, treatment performance varies by system.
Always verify the specific contaminant-reduction claims of the model you’re considering.
Can a Standard Pitcher Filter Remove Radium?
You should not assume that a basic pitcher filter removes radium.
Many pitcher filters focus on:
- Taste
- Odor
- Chlorine reduction
Radium removal requires specialized treatment technologies.
Always review product certifications and performance claims before purchasing.
Frequently Asked Questions
What is the EPA limit for radium in drinking water?
The federal maximum contaminant level for combined radium-226 and radium-228 is 5 pCi/L. (US EPA)
Is radium dangerous?
Long-term exposure above regulatory limits can increase the risk of cancer. (US EPA)
Can you taste radium in water?
No. Radium is tasteless, odorless, and invisible.
How do I know if my water contains radium?
The only reliable method is laboratory testing.
Does reverse osmosis remove radium?
Yes. EPA lists reverse osmosis as a best available treatment technology for radium removal. (EPA NEPIS)
Should private well owners test for radium?
Yes, especially in areas known for naturally occurring radionuclides. Private wells are not regulated under federal drinking-water rules. (US EPA)
Final Thoughts
Radium is a naturally occurring radioactive contaminant that can enter groundwater through geological formations. While many water supplies contain only trace amounts, elevated concentrations can increase cancer risk over long periods of exposure.
The good news is that effective treatment technologies exist. EPA identifies ion exchange, lime softening, and reverse osmosis as effective technologies for reducing radium in drinking water. (EPA NEPIS)
The first step is always testing. Once you know your radium concentration, you can determine whether a whole-house treatment system or a point-of-use reverse osmosis system is the most appropriate solution.
For more information about radium and other contaminants including arsenic, chromium-6, PFAS, lead, nitrates, mercury, manganese, copper, and sulfur, visit RevOsmo’s:
Drinking Water Contaminants Explained
https://revosmo.com/drinking-water-contaminants-explained/
Disclaimer: This article is for general educational purposes and is not a substitute for laboratory water testing, medical advice, or professional water-treatment advice. Water quality varies significantly by location and source. Always test your water and verify current regulatory requirements and product-specific contaminant-reduction claims before selecting treatment equipment.
