EPA legal limit
30 ppb
Maximum Contaminant Level
EWG health guideline
0.43 ppb
Science-based, stricter target
IARC classification
Group 1
Cancer research classification
Health effects
Both a toxic heavy metal and a radioactive element. Kidney damage is the primary toxicological concern at lower concentrations; cancer risk increases at higher levels. The EWG health guideline of 0.43 ppb is based on kidney toxicity data.
Where it comes from
Natural geological sources. Uranium dissolves into groundwater from uranium-bearing minerals. Most concentrated in western states, Florida, and the Great Plains.
How it's regulated
EPA MCL of 30 ppb based on kidney toxicity and cancer risk.
The EPA vs EWG gap
The legal limit (30 ppb) is 70× higher than the EWG health guideline (0.43 ppb). Water can be legally compliant while still exceeding the science-based threshold.
How to filter uranium
Not all filters address uranium. Look for independently certified filters—NSF International certification means the removal claim has been independently verified.
Uranium is not removed by water ionization. Reverse osmosis is the recommended filtration method.
Frequently asked questions
What is uranium?
A naturally occurring radioactive element found in rock, soil, and water. Detected in groundwater supplies throughout the U.S., particularly in the West.
What are the health effects of uranium?
Both a toxic heavy metal and a radioactive element. Kidney damage is the primary toxicological concern at lower concentrations; cancer risk increases at higher levels. The EWG health guideline of 0.43 ppb is based on kidney toxicity data.
Is uranium regulated in drinking water?
EPA MCL of 30 ppb based on kidney toxicity and cancer risk.
Where does uranium come from?
Natural geological sources. Uranium dissolves into groundwater from uranium-bearing minerals. Most concentrated in western states, Florida, and the Great Plains.
How do I remove uranium from tap water?
The most effective methods for removing uranium are: Reverse osmosis (RO), NSF 58 certified RO system, Ion exchange resin. Look for NSF-certified systems—independent certification confirms removal claims have been verified.
Is uranium in your water?
Enter your ZIP code to see the measured level in your specific utility.