Portland, Ore. -- (KGW) The Portland Water Bureau issued a 'boil water alert' Friday morning for the entire water district after the city detected E. coli in water samples.
At a press conference at noon Friday, Water Bureau Director David Shaff said this was the largest boil water alert in the city's history, impacting some 670,000 water users.
The source of the contamination was Mount Tabor reservoirs 1 and 5. The alert includes the city of Portland, but also the cities of Tigard, King City, parts of Gresham and other districts (see below for full list.)
"Until further notice, all Portland Water Bureau customers and those in the affected areas should boil all tap water used for drinking, food preparation, tooth brushing and ice for at least one minute. Ice or any beverages prepared with un-boiled tap water on or after May 20 should be discarded," the alert reads.
"In three separate incidents from May 20 to May 23, repeat water samples confirmed the presence of total coliform and E. coli in routine drinking water samples," Shaff said.
Tri-County Health Officer Dr. Paul Lewis said the E. coli came from animal fecal matter. The most likely symptom from people drinking contaminated water would be diarrhea. Lewis said that he did not believe many people would be impacted.
The city tests water in the system about 240 times a month. In addition to the Mount Tabor Reservoirs, contaminated water was found at the Southeast 2nd Avenue and Salmon Street water sampling station, according to the city.
Reservoir 5 was the center of controversy in April when the city declared it would flush 38 million gallons of water into the sewers after a teenager allegedly urinated in the water.
The city sampled the water on Tuesday. The sample tested positive for E. coli the following day. Continued tests triggered a mandatory alert, officials said.
The Centers for Disease Control and Prevention advise that people should boil tap water even if it is filtered. Most kitchen and other household water filters typically do not remove bacteria or viruses.
Contamination can occur when there is a loss of water pressure, a pipe break, or conditions that expose drinking water to outside elements, the city said.
An investigation into the problem was under way.
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Photos courtesy of KGW.
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