UPDATE, SATURDAY, MAY 24: The Water Bureau lifted the boil-water notice at 11 am, saying tap water is again safe to drink.
"Follow-up testing of drinking water has shown the absence of bacterial contamination," Water Bureau officials write. "The Portland Water Bureau recommends flushing all taps for two minutes or until the water runs cold before consuming for the first time. This will flush any potentially contaminated water from the plumbing."
ORIGINAL POST, FRIDAY, MAY 23, 11:38 AM: The Portland Water Bureau has told its customers to boil their tap water after samples in two Mt. Tabor reservoirs tested positive for E. coli bacteria over the past three days.
The notice is precautionary. No one has reported getting sick and, as WW reported after a similar scare in 2012, the chances of disease are extremely small.
But the repeated findings of bacteria at Mt. Tabor mean residents citywide should "boil all tap water used for drinking, food preparation, tooth brushing and ice for at least one minute," the Water Bureau writes on its website (which has crashed repeatedly following the notice).
"In three separate incidents from May 20 to May 23," the bureau writes, "repeat water samples confirmed the presence of total coliform and E. coli in routine drinking water samples.
"The water samples that tested positive for bacteria were collected at the outlets of Mt. Tabor Reservoirs 1 and 5, and at the SE 2nd Avenue and Salmon Street water sampling station," the notice says. "Both reservoirs have been taken offline."
That timing is remarkable—it means the first sample was found on Election Day, when voters were deciding whether of not to remove control of Portland's water supply from City Hall. (They voted no.)
But the timeline of the tests and the warning appears to follow a similar schedule to the 2012 boil-water notice, which was issued two days after a positive test.
E. coli and coliform are types of bacteria common in animal feces.
WW reported in 2012 that the chances of illness from finding such positive samples was vanishingly small. We asked Dr. Gary Oxman, then health officer for Multnomah County, how many bears it would take defecating in the Bull Run Watershed to cause a disease outbreak.
His answer: Many, many bears defecating continually, or "one bear that had just the right organism, defecating repeatedly."
UPDATE, 12:25 pm: Portland Water Bureau director David Shaff urged the public to boil water at a noon press conference, but public health officials said the chances of an uptick in diarrhea were low.
"We err on the side of caution," says City Commissioner Nick Fish, who oversees the Water Bureau. "In a perfect world, we'll be able to tell everybody tomorrow morning to stand down. We're painfully aware that we're headed into Memorial Day weekend."
Meanwhile, the boil-water notice has had one immediate consequence: Stumptown Coffee has shut down all its cafes for the rest of the day.