Which naturally occurring radioactive substance can be found in well water?

Radium is a naturally occurring radioactive substance that can be found in well water. It is a member of the uranium decay series and can leach into groundwater from rocks and soil. Wells that are drilled into uranium-rich areas or near natural deposits of radium may contain elevated levels of this element.

Radium is of particular concern due to its health risks, including its potential to cause cancer, as it can accumulate in bones and other tissues in the body. Testing for radium in drinking water is important to ensure that it does not exceed the safe drinking water standards set by regulatory agencies.

While uranium, radon, and polonium are also radioactive substances that can be associated with geological formations, radium is specifically noted for its presence in well water due to its solubility and mobility in groundwater systems, particularly in certain geographic areas where the geology is conducive to its presence.