Uranium in Community Water Systems

For Minnesota's Community Water Systems:

Uranium occurs naturally in the environment.

Uranium occurs naturally in our environment. Uranium is a silver-colored metal that is radioactive. Small amounts of uranium occur naturally in rocks, soil, and water. Natural uranium is composed of three forms (also known as isotopes): uranium-234, uranium-235, and uranium-238. Uranium 238 is the most predominant form. Over 99 percent of the uranium found in nature is uranium-238. Uranium is not stable but breaks down into other elements including radium and radon. This process is called decay, and alpha radiation is released.

Uranium can affect health.

Naturally occurring uranium has very low levels of radioactivity. However, the chemical properties of uranium in drinking water are of greater concern than its radioactivity. Most ingested uranium is eliminated from the body. However, a small amount is absorbed and carried through the bloodstream. Studies show that drinking water with elevated levels of uranium can affect the kidneys over time. Bathing and showering with water that contains uranium is not a health concern.

By law, all community water systems must be monitored for radioactivity. The testing process for water samples begins with a screening for “gross alpha particle activity,” which measures the total amount of one type of radioactivity called alpha decay. If gross alpha activity is found at levels exceeding 20.1 pCi/L, further testing for Uranium is conducted. Uranium and other levels or radioactivity in water are measured in picocuries per liter (pCi/L) of water. The federal Maximum Contaminant Level (MCL) for uranium is 20.1 picocuries per liter (pCi/L). If a system's average uranium levels are above the MCL, MDH will help the system reduce uranium.


Mean Uranium levels in Minnesota Community Water Systems

Percent of tested systems, by mean Uranium concentration
The federal Maximum Contaminant Level (MCL) for Uranium is 20.1 picocuries per liter (pCi/L).
The federal Maximum Contaminant Level (MCL) for Uranium is 20.1 picocuries per liter (pCi/L).

Maximum Uranium levels of Minnesota Community Water Systems

Percent of tested systems, by maximum Uranium concentration
The federal Maximum Contaminant Level (MCL) for Uranium is 20.1 picocuries per liter (pCi/L).
The federal Maximum Contaminant Level (MCL) for Uranium is 20.1 picocuries per liter (pCi/L).

Most drink water with Uranium below the MCL

Population served

People served, by mean Uranium annual concentration of their Community Water Systems, 2015
Uranium level Number of Systems Population Served Percent
0-5 119 830,285 87.5%
5-15 6 46,945 4.4%
15-30 11 16,429 8.1%
<30 0 0 0.0%

What can be done about Uranium in drinking water?

Sometimes a system can find a new water source. It may also blend water from more than one source to the point that the blended water does not have unacceptable levels of uranium Another option is to install a treatment process to reduce the radium levels. Treatment options include cation exchange (which is similar to home water softening), reverse-osmosis, lime softening, electrodialysis, or filtering the water through greensand or anthracite. MDH will do a study to demonstrate that a chosen option will work. A water system will consider many factors, including cost, in deciding on an option.

Related resources:

MN Drinking water standards for contaminants

CDC Environmental Public Health Tracking-Uranium and your health

Radionuclides Rule: EPA Drinking Water requirements for states and public water systems