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Portland Water Bureau

From forest to faucet, we deliver the best drinking water in the world.


1120 SW Fifth Ave, Suite 600, Portland, OR 97204

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Radon in Portland’s drinking water does not pose a significant health concern. The risk associated with radon comes from long-term exposure to breathing air with high levels of radon, such as from indoor air where radon released from soils can accumulate.

Radon is a naturally occurring radioactive gas that is a health concern when inhaled for long periods of time. It is not generally a health concern when present in drinking water and is not currently regulated by the Environmental Protection Agency (EPA) or State of Oregon.

Radon has been detected at varying levels in Portland’s groundwater wells from the Columbia South Shore Well Field, Portland’s secondary source of drinking water. The Water Bureau turns to groundwater during annual maintenance, when heavy winter storms prevent use of the Bull Run source and during particularly hot, dry summers to supplement the Bull Run water supply.

Overall exposure to radon in Portland’s drinking water is very low.  Radon is rarely detected from the Bull Run source and only then, at extremely low levels. Radon from groundwater ranges from 131-390 pCi/L. In August 2015, radon was detected at the groundwater pump station at 340 pCi/L. Although no standard has been adopted, the Environmental Protection Agency has proposed regulating radon in drinking water at 4,000 pCi/L (picocuries per liter).  This level is approximately 10-30 times higher than what the Water Bureau has recorded from the Columbia South Shore Well Field. Additional testing conducted in the distribution system, closer to customers’ taps, found significantly lower levels of radon ranging from 34-140 pCi/L.

Radon is not currently a regulated contaminant, and therefore monitoring is not required. However, the Portland Water Bureau has been proactively monitoring radon for many years. The Water Bureau also reports radon results in the Annual Drinking Water Quality Report when radon is tested for and detected.

In Portland the greatest source of radon is from naturally occurring radon gas that enters homes and buildings through the foundation. Customers concerned about radon exposure are encouraged to test their home for radon. The EPA, Surgeon General, and the Oregon Health Authority all recommend testing your home for radon gas.  The American Lung Association of Oregon offers test kits at:

Additional information about radon can be found at the Oregon Health Authority’s radon webpage or from the EPA’s radon webpage or Radon Hotline at 800-SOS-RADON.