City investigating false results

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This article was published 30/01/2015 (3913 days ago), so information in it may no longer be current.

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The end of Winnipeg’s 46-hour boil-water advisory has led to the beginning of an investigation into how water-sample tests yielded what’s now believed to be erroneous evidence of fecal contamination of the city’s water supply.

Winnipeg residents were advised to boil their water from 5:45 p.m. on Tuesday to 3:31 p.m. on Thursday, when Mayor Brian Bowman first announced the end of the advisory on Twitter and then strode up to reporters and sipped from a glass of tap water.

“We’ve got a clean bill of health,” the mayor said in the foyer at city hall. “I know and appreciate the inconvenience we’ve all, in different ways, had to endure.”

The precautionary boil-water advisory, unprecedented in the city’s recent history, was ordered after six of 39 water samples collected on Monday tested positive for coliform bacteria, whose presence in water suggests fecal contamination and the possible presence of other, potentially more dangerous pathogens.

The coliform counts in the six positive samples ranged from one to nine units per 100 millilitres. Provincial health officials ordered the boil-water advisory Tuesday because Health Canada’s maximum coliform count for drinking water is zero.

Yet from the beginning of the advisory, city water engineers suspected the tests were inaccurate due to the presence of bacteria-killing chlorine in the same water samples as the coliform bacteria, as well as the absence of bacteria in water collected both upstream and downstream of the six problematic locations.

When two consecutive days of re-sampling and re-testing yielded no evidence of bacteria, the advisory was lifted and the city is left trying to figure out how six separate water samples yielded erroneous results.

“We do not know what had led to this,” said Diane Sacher, director of Winnipeg’s water and waste department. “Now that we have the all-clear, obviously we are going to be shifting our focus to find out what has happened (and) why did we have those positive test results.

“That’s obviously going to be a high priority for us now to determine why that happened and try to find out what we can do to prevent that from happening again.”

Sacher said a city investigation into the cause of a false positive for coliform bacteria in St. Vital in 2013 was inconclusive, but the city nonetheless changed its water-sampling procedures.

The new investigation may attempt to discern whether false positives were caused by contaminated taps or water-sampling containers, accidental contamination of the samples during collection or accidental contamination of the samples during laboratory analysis.

Sacher said it’s too soon to say whether human error was involved. “We’re only in hour one since the advisory was lifted,” she said.

‘We’ve got a clean bill of health. I know and appreciate the inconvenience we’ve all, in different ways, had to endure’

— Mayor Brian Bowman

Bowman repeated there are no plans to compensate businesses inconvenienced by the advisory, noting the city had no choice but to follow the provincial order, which in turn was governed by Health Canada protocols.

“It wasn’t something we had an option on,” he said.

The rookie mayor said he and his staff learned a lot about emergency operations through the two-day advisory and thanked city staff for their communication efforts. “I believe we’ve been very forthcoming with information as it became available,” Bowman said.

City staff held four press conferences between the beginning and end of the advisories. The mayor attended three of them and filmed a pair of explanatory videos that were posted on the city’s YouTube channel.

bartley.kives@freepress.mb.ca