What is Uranium* and Why Does It Matter?

Uranium is a naturally occurring radioactive metal found in rocks and soil across much of the United States. As groundwater moves through uranium-bearing rock formations, it dissolves trace amounts of the metal and carries it into wells and municipal water systems. Unlike many water contaminants that come from industrial pollution, uranium in drinking water is largely a geological problem — it's been there long before anyone turned on a tap.

The health risks from uranium are twofold. It acts as both a radioactive element and a heavy metal, meaning it can damage the body in two distinct ways. Long-term exposure is most strongly linked to kidney damage, because the kidneys filter uranium out of the blood and absorb the highest concentrations. The World Health Organization (WHO) and the EPA also classify uranium as a possible human carcinogen, with prolonged exposure raising the risk of certain cancers. Children and pregnant women face heightened concern, since developing kidneys and tissues are more vulnerable to both chemical and radioactive harm.

The EPA's legal limit for uranium in drinking water is 30 micrograms per liter (µg/L), set back in 2001. The Environmental Working Group (EWG) considers that standard dangerously outdated. Their health guideline sits at 0.43 picocuries per liter (pCi/L) — a much stricter threshold based on current cancer risk science. Of the 926 water systems across the country that detected uranium, 640 exceeded the EWG health guideline. The average level found was 1.975 pCi/L, and the highest recorded level reached 22.2 pCi/L. That peak is more than 50 times above what the EWG considers safe. Many of these systems still technically comply with federal law, which means families could be drinking uranium-contaminated water with no warning from regulators.

Geography plays a major role in where uranium shows up. Texas leads the country with 221 affected water systems, followed by California with 141 and Colorado with 105. Oklahoma and New York each reported 49 affected systems. The pattern isn't random. Texas, Colorado, and Oklahoma sit atop ancient rock formations naturally rich in uranium — including the Ogallala Aquifer and various granite-heavy geological zones. Communities that rely on well water or smaller groundwater-fed systems in these regions face the greatest exposure. California's affected systems are concentrated in areas with granite bedrock, particularly in rural parts of the Central Valley and the Sierra Nevada foothills. New York's uranium detections tend to cluster in regions with similar geological conditions, especially where private wells draw from bedrock sources.

The good news is that uranium is one of the more treatable contaminants in drinking water. Reverse osmosis (RO) filtration is the most effective option for homeowners. A properly functioning RO system removes up to 95–99% of uranium from tap water, according to the EPA. Ion exchange systems — a technology that swaps uranium ions for harmless ones — also perform well and are commonly used in municipal treatment. Activated alumina filters are another proven option, particularly for point-of-entry systems that treat water for the whole house. If you're on a private well in Texas, Colorado, California, or another high-risk state, testing your water is the essential first step. Many people don't know uranium is present because it has no taste, smell, or color. Echo Water's home filtration systems use multi-stage reverse osmosis to bring uranium levels well below both EPA and EWG thresholds — giving you a practical, reliable layer of protection while regulators catch up to the science.

Regulatory Standards for Uranium*

Cities With the Highest Uranium* Levels

States Most Affected by Uranium*

Frequently Asked Questions

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