Recent water tests show Grinnell’s public water system has elevated levels of radium and gross alpha, both naturally occurring substances found in groundwater. While levels are above federal drinking water standards, this is not an emergency, the water remains safe to drink and use for daily activities.
Test results:
Radium (combined 226/228)
- Standard or maximum contaminant level (MCL): 5 picocuries per liter (pCi/L)
- Grinnell’s average: 6.4 pCi/L (based on testing results received June 30, 2025)
Gross Alpha (excluding radon and uranium)
- Standard (MCL): 15 pCi/L
- Grinnell’s 2024 quarterly results:
- Q1: 15.65 pCi/L
- Q2: 20.1 pCi/L
- Q3: 20.5 pCi/L
- Q4: 21.8 pCi/L
Is the water safe?
Yes. While above the federal limit, the detected levels do not pose an immediate health risk. Long-term exposure to higher levels may carry some risk. Those with health concerns should consult their doctor.
What are radium and gross alpha?
Radium is a naturally occurring radioactive metal found in rocks and soil.
Gross alpha measures radiation released as elements (such as radium) break down in the environment.
Because radium emits alpha particles as it breaks down, elevated levels of radium in the water contribute to higher gross alpha readings. The U.S. Environmental Protection Agency (EPA) sets limits on both to protect long-term health.
Treatment options
Certain types of home water softeners and reverse osmosis treatment units can be effective at removing radium from drinking water. Boiling water and carbon-based drinking water filters are not effective methods of removing radium.
What is being done?
Grinnell’s current water treatment plant does not have the ability to remove radiological contaminants, but a new treatment plant is under construction with the technology to reduce them. The plant is expected to be operational by December 2026. In the meantime, the water department is using the best available wells to help manage contaminant levels, though current treatment options cannot fully lower them below the regulatory limit.
For more information
Contact: Keagan Richmond, Water Director, 702 Main Street, 641-990-7521
Drinking Water Requirements-Radionuclides Rule, U.S. EPA
Radium Testing Results in Public Water, Iowa Health & Human Services
City of Grinnell Water Improvements Overview
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