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The City of Portland, Oregon

Portland Water Bureau

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

Customer Service: 503-823-7770


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Portland's Drinking Water: What You Need to Know About Cryptosporidium

We’d like to clear up some information after a news report last week on Cryptosporidium caused some confusion.

Last week’s Cryptosporidium detection is part of a seasonal pattern we have seen since 2017. Portland’s water is safe to drink for the general population.

As always, people who are severely immune-compromised, such as people who have had an organ transplant, HIV/AIDS, or cancer treatment, should consult with their health care providers about the safety of drinking tap water. Those people may consider drinking bottled water or using a water filter and can find additional information in this educational brochure.

History of Cryptosporidium Detections

Since 2017, we have detected Cryptosporidium seasonally during the rainy season. Last week’s detection is the first detection we’ve had this rainy season, and low-level Cryptosporidium detections may continue through the winter. During last year’s rainy season (October 2018 through May 2019), we had 38 days with a low-level detection of Cryptosporidium. When we detect Cryptosporidium, we post the results online.

We are working in close contact with our public health partners at Multnomah County and the state who are monitoring our community’s public health. At this time, they have not found an increase in illness and are advising that customers do not need to take any additional precautions. The Portland Water Bureau is ready to tell the public if additional precautions become necessary. Accurate, up-to-date information about your drinking water is available on official Portland Water Bureau accounts at Facebook, Twitter, NextDoor, and the Water Blog.


Immune-compromised customers are encouraged to contact their health care provider. For all other questions about Cryptosproidium, contact the Water Bureau’s Water Quality Line at 503-823-7525.

Cryptosporidium Background

The Bull Run Watershed is a highly protected unfiltered drinking water source. Cryptosporidium, a potentially disease-causing microorganism, is occasionally found in the Bull Run drinking water supply. Exposure to Cryptosporidium in drinking water, especially for those with a condition that severely weakens their immune system, can lead to potentially serious illness.

Portland is working to install filtration by September 2027 under a compliance schedule with Oregon Health Authority. The Bull Run Filtration Project will remove Cryptosporidium and other contaminants from the Bull Run water supply, producing cleaner, safer water for the one million people who use our water now and for future generations. In the meantime, Portland Water Bureau is implementing interim measures such as watershed protection and additional monitoring to protect public health. Learn more about Cryptosporidium on our Information on Cryptosporidium webpage.