EWG Tap Water Atlas


Radiological contaminants like radium leach into water from natural deposits in the Earth’s crust and from industrial energy extraction processes like mining, drilling and fracking. Drinking water contaminated with radioactive substances increases the risk of cancer and may harm fetal development.

Radium is found in the tap water of 153 million people in 49 states. The extraction, processing and disposal of natural resources like uranium, oil and gas can release radium and other radiological contaminants from soil and rock into water supplies.

The EPA’s legal limit for combined levels of radium isotopes in tap water, 5 picocuries per liter, or pCi/L, was set in 1976, and is based on the cost of removal. EWG’s health standards are hundreds of times more stringent than this federal limit: 0.05 pCi/L for radium-226 and 0.019 pCi/L for radium-228. These are the amounts the California Office of Environmental Health Hazard Assessment says are expected to cause no more than one case of cancer in 1 million people who drink it for a lifetime.

Ion exchange and reverse osmosis systems can effectively remove radium from tap water at both the utility and home levels.