PORTLAND, Ore. (KOIN) — A potentially disease-causing microorganism was detected in Portland’s main drinking water source.

Officials say the water was collected from the Bull Run Watershed on Sunday and tested positive for cryptosporidium, a parasite that causes cryptosporidiosis. This is a serious disease with symptoms including diarrhea, vomiting, fever and stomach pain.

Although those with healthy immune systems can recover from cryptosporidium exposure without medical help, immunocompromised individuals may experience more severe symptoms. In rare cases, it could lead to serious or life-threatening illness.

The water last tested positive for cryptosporidium in May. The Portland Water Bureau does not currently treat for cryptosporidium, though it is required to do so under drinking water regulations. 

According to the bureau, “Portland is working to install filtration by September 2027 under a compliance schedule with Oregon Health Authority.” Until then, public health officials have implemented watershed protections and monitoring.

The Portland Water Bureau serves nearly a million residents in the area. However, health officials say customers “do not need to take any additional precautions.”

Areas that receive all or part of their water from the water supply at Bull Run include: Burlington, City of Gresham, City of Sandy, City of Tualatin, Green Valley, GNR, Hideaway Hills, Lake Grove, Lorna Domestic Water, Lusted, Palatine Hill, Pleasant Home, Raleigh, Rockwood, Skyview Acres, Tualatin Valley, Two Rivers, Valley View and West Slope Water Districts.

Portlanders with concerns about the quality of their water can contact the bureau at 503-823-7525.