Feeling thirsty? Before you pour yourself a glass of water, you might want to take a closer look at a new map released by the Environmental Working Group (EWG) that pinpoints the locations in the United States where drinking water contains high levels of radium, a naturally-occurring radioactive element that's also a known carcinogen.

As you can see, radium contamination can be found all over the U.S. according to the EWG's data. The group analyzed test results from public water systems across the country from 2010 to 2015 and found that drinking water for more than 170 million Americans may contain levels of radium deemed unsafe by the Environmental Protection Agency's standards.

The current federal standard for radium in the U.S. is no more than 5 pCi/L (picocuries per liter) for the combined amounts of the two most common isotopes of radium found in water, radium-226 and radium-228. Yet some facilities on the map reported radium levels well in excess of this amount, such as Andover, Minnesota, with 7.143 pCi/L; Brady, Texas with 9.249 pCi/L; or the Waukesha Water Utility near Milwaukee with 10.683 pCi/L.

Where and why radium is a problem

Woman drinking water Radium cannot be seen, tasted or smelled in drinking water. (Photo: sebra/Shutterstock)

What's the big deal about radium? In the natural environment, radium is found at low levels in soil, water, rocks, coal, plants and food. But radium also happens to be radioactive, so even low-level exposure could increase your risk for cancer. Even though 80 percent of the radium consumed or inhaled will be excreted by the body, the remaining 20 percent will enter the blood stream and travel to all areas of the body, with a portion of that percentage accumulating in the bones, according to an EPA factsheet.

The EWG found radium in all 50 states, with 158 public water systems in 27 states reporting radium in amounts that exceeded the federal legal limit. California has the most residents impacted by radiation in drinking water, with 64 percent of the population — or 25 million people — affected by the almost 800 systems that reported detectable levels of radium.

Texas is another radium hotspot. The EWG found that the state has the most widespread contamination with about 80 percent of Texans affected. More than 3,500 utilities in Texas, which serve more than 22 million people, reported detectable levels of radium

Curious to know if the water in your local community is contaminated with radium? Use this link to access the EWG's interactive map and plug in your ZIPcode to see the results. If you get your groundwater from a well, it's a good idea to get it tested. If radium is a concern in your area, you may want to purchase a water filter that's certified to remove it.

The tap water of 170 million Americans may contain unsafe levels of radium
Radium, a naturally-occurring radioactive element that's also a known carcinogen, can be found in water systems across the U.S.