Radionuclides in Drinking Water
Regulated radionuclides for public water systems, maximum contaminant levels, monitoring and sampling, and health effects.
On this page:
- Regulated Radionuclides
- Maximum Contaminant Levels
- Monitoring and Sampling
- Health Effects
- Treatment Options
- Related Links
In Texas, radionuclides in drinking water most often come from naturally occurring radioactive material, typically in groundwater from the Hickory Aquifer in Central Texas, Ogallala Aquifer in North Texas, or the northern portion of the Gulf Coast Aquifer. The main concern is a group of substances that produce the high-energy form of radioactivity known as alpha particles—specifically, radium, uranium, and overall alpha radioactivity measured as a maximum contaminant level.
Regulated Radionuclides
- Radium
- Uranium
- Gross Alpha Particles
Regulations—from the Radionuclides Rule—apply to community and nontransient noncommunity public water systems (PWS) and excludes purchased water systems.
Maximum Contaminant Levels
PWSs must adhere to requirements for maximum contaminant levels (MCL). Compliance is determined based on a running annual average of quarterly sampling at each point where treated water enters the distribution system. If that average exceeds the MCL, a PWS must notify customers as soon as possible but no later than 30 days after the violation is identified.
Radioactivity is often measured using curies. The unit of measurement pCi/L stands for picocuries per liter and measures how much radioactivity is in one liter of water. The prefix “pico” means one out of one trillion.
Table - Maximum Contaminant Levels (MCL)
| Compound | MCL |
| Gross Alpha Particles | 15 picoCuries per Liter (pCi/L) |
| Radium | 5 pCi/L |
| Uranium | 30 pCi/L |
Consumer Confidence Report - Community water systems must provide the minimum, maximum, and average levels of any contaminant detected in their annual Consumer Confidence Report to customers by July 1 of each year. A community water system supplies water to the same population year-round.
Monitoring and Sampling
PWS can protect their customers from long-term health risks by regularly monitoring the levels of radionuclides. Every PWS in Texas must allow for sampling of chemical contaminants. Unlike sampling for lead and copper, water quality parameters, microbes (coliform and E. coli), and disinfectant residuals—TCEQ uses contractors to collect samples for gross alpha particles, radium, and uranium.
- Texas Drinking Water Watch - Find sampling results.
- Interpreting Chemical Analysis Results– Learn how to understand test results.
- Public Notice Language for Drinking Water Compliance– If your public water system does exceed any standards, you can find required language and certificate of delivery documents by contaminant to use for public notification.
Only chemicals that are known to pose a risk to human health require routine sampling and action if violations occur.
Health Effects
An MCL exceedance of radium, uranium, and gross alpha particles is not an emergency. However, some people who drink water containing these compounds may have an increased risk of kidney damage or cancer.
Systems that exceed the MCL must identify options to reduce radionuclide levels in their treated water. The only way to remove the risk entirely is to reduce the level to zero. However, the cost of completely removing the radionuclides and disposing of the resulting waste safely could make the water too expensive to use.
Treatment Options
Treatment options include finding a new source of water or blending the water with another source with lower levels of radionuclides. Radium and uranium can be removed using oxidation, reverse osmosis, lime softening, and filtering through greensand. For more detailed information about treatment options see federal regulations on:
- Best Available Technologies (BATs)
- Small System Compliance Technologies chosen for their effectiveness and affordability
Related Links
Radionuclide Rule Compliance Help for Public Water Systems
Materials provided by EPA for public water system owners and operators to help comply with requirements of the Radionuclide Rule.
Radionuclides in Drinking Water: A Small Entity Compliance Guide
This EPA guide provides the operator of a small PWS with an understandable overview of the Radionuclides Rule.
Technical Guidance for Public Water System Operators and Engineers
Find information about technical questions on topics such as submitting plans, exploring treatment options, or requesting exceptions to design or capacity rules.
Financial, Managerial and Technical Assistance
TCEQ offers FREE financial, managerial, and technical (FMT) assistance to help public water systems comply with regulations. Contact FMT to help with issues such as, but not limited to preventing operational problems, performing capacity assessments, and training about how to comply with rule requirements.
Radionuclide Testing for Approval of Well Completion
Find answers to technical questions such as how to submit plans or request exceptions to design or capacity rules, and information on treatment options.