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Emerging Contaminants in Drinking Water

Image of outdoor water source showing green algal bloom (source EPA)

Emerging contaminants are naturally occurring or manmade chemicals present in drinking water that are known or suspected to pose risks to human health and are not yet subject to federal regulatory oversight. Some emerging contaminants of concern in Oregon include toxins produced by cyanobacteria (cyanotoxins), Per- and Polyfluoroalkyl Substances (PFAS), and Manganese.

The US Environmental Protection Agency (EPA) uses the Unregulated Contaminant Monitoring Rule (UCMR) to collect data for contaminants that are suspected to be present in drinking water and do not have health-based standards set under the Safe Drinking Water Act (SDWA).

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Oregon Health Authority (OHA) has developed regulations that require drinking water systems using surface water sources susceptible to harmful algae blooms to routinely test for cyanotoxins that these blooms produce and notify the public about the test results.

Per- and Polyfluoroalkyl Substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that includes PFOA, PFOS and GenX chemicals. Since the 1940s, PFAS have been manufactured and used in a variety of industries around the globe, including in the United States. PFOA and PFOS have been the most extensively produced and studied of these chemicals. Both are very persistent in the environment and in the human body. Exposure to certain PFAS can lead to adverse human health effects.  For more information, see the OHA Environmental Public Health PFAS webpage.

In 2016, EPA established a health advisory level for two PFAS in drinking water, PFOS and PFOA, at 70 parts per trillion (ppt) individually or combined. OHA's expectation is that public water systems will notify the public if a health advisory level is exceeded. This health advisory level offers a margin of protection for all Americans throughout their life from adverse health effects resulting from exposure to PFOA and PFOS in drinking water. EPA's health advisories are non-enforceable and non-regulatory and provide technical information to states agencies and other public health officials on health effects, analytical methodologies, and treatment technologies associated with drinking water contamination.

Six PFAS (including PFOS and PFOA) were among the list of contaminants that public water systems were required to monitor for under the third Unregulated Contaminant Monitoring Rule (UCMR3). All public water systems nationwide serving more than 10,000 people and 800 representative systems serving 10,000 or fewer people monitored for these and other unregulated contaminants during a 12-month period from January 2013 through December 2015.  In Oregon, 65 public water systems monitored for these PFAS contaminants and there were no detections reported. 


Manganese is a naturally occurring element found in soil, water, and air. It is commonly found in foods such as nuts, legumes, seeds, grains, and green leafy vegetables and in drinking water. Our bodies require small amounts of manganese to stay healthy. Too much manganese can increase the risk of health problems, particularly for infants under 6 months old. Infants are more at risk than older children and adults because their brains and bodies are quickly developing. Formula-fed infants get enough manganese from formula to meet their dietary needs. However, they may get too much manganese (above the recommended amount for nutrition) in their bodies when formula is mixed with water that contains manganese. Infants exposed to manganese over the EPA established health advisory level of 0.3 mg/L for 10 or more days may experience learning or behavioral problems. Adults who drink water with high levels of manganese for many years may experience impacts to their nervous system. EPA established a lifetime health advisory level of 0.3 mg/L which means adverse health effects are not expected below this level.

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