Cryptosporidium was found at low levels in Portland city water several years ago. As a result, the Portland Water Bureau now tests for cryptosporidium almost daily, and has begun a project to treat our city water to remove Cryptosporidium . The Water Bureau’s website cited in the footnote contains this passage:

“…the Portland Water does not currently treat for Cryptosporidium, but is required to do so under the drinking water regulations. Portland is working to install filtration by 2027 under a compliance schedule with Oregon Health Authority. In the meantime, Portland Water Bureau is implementing interim measures such as watershed protection and additional monitoring to protect public health. Consultation with public health officials has concluded that at this time, customers do not need to take any additional precautions.

“Exposure to Cryptosporidium can cause cryptosporidiosis, a serious illness. Symptoms can include diarrhea, vomiting, fever, and stomach pain. People with healthy immune systems recover without medical treatment. According to the Centers for Disease Control and Prevention (CDC), people with severely weakened immune systems are at risk for more serious disease. Symptoms may be more severe and could lead to serious life-threatening illness. Examples of people with weakened immune systems include those with AIDS, those with inherited diseases that affect the immune system, and cancer and transplant patients who are taking certain immunosuppressive drugs.

“The Environmental Protection Agency has estimated that a small percentage of the population could experience gastrointestinal illness from Cryptosporidium and advises that customers who are immunocompromised and receive their drinking water from the Bull Run Watershed consult with their health care professional about the safety of drinking the tap water.”

The first paragraph of this passage from the website says that the Portland Water Bureau has concluded that Portland water is safe to drink, while the third paragraph says that the EPA expects some customers may get sick from drinking Portland water, especially those who are immunocompromised.

Portland Water Bureau tests frequently for Cryptosporidium and publishes test results on its website[2]. Water samples tested positively for Cryptosporidium in 8 months out of the year 2019. The positive test results have continued in January and February of 2020.

One way to render Cryptosporidium and other microbiological contaminants harmless in drinking water is to expose the water to ultraviolet light from mercury vapor fluorescent tubes (UV-C light at a wavelength of 254 nanometers) at a dose of 40 microJoules per square centimeter.  This method is used at industrial scale in some other public water systems.  UV water disinfection is also available on a smaller scale, appropriate for single families, in the form of the DayZero UV-H2O-Box products.  The DayZero products were originally conceived as a way to safely use water from streams and other unconventional sources after a natural disaster, until normal utility services are restored.  They have been adapted for routine daily use here in Portland as a way to mitigate the hazard from Cryptosporidium contamination, in the interim until the City’s new treatment facility goes into operation in 2027.

Using a UV-H2O-Box at home to treat for Cryptosporidium is straightforward.  You simply fill the tank with a gallon of water, turn on the UV light, and leave it on for one minute.  Treatment for one minute deactivates 99.999% of most microbiological contaminants[1], including Cryptosporidium, Giardia, bacteria, and most viruses.  Treated water may be used immediately or left in the tank until needed.  Power for the UV light can come from an adapter which plugs into a household electrical outlet.  For emergency use, there is an also an adapter for automobile cigarette lighter outlets and, on some models, a hand-cranked generator.