False positive E. coli test not a surprise: Microbiologist

WINNIPEG — It didn’t take long for questions to arise about the water testing process itself.

After three rounds of tests being done – critics say they’re not surprised by the false positive E. coli results.

Microbiologists at Central Testing Laboratory test water samples everyday for potentially dangerous bacteria’s.

“There’s always a chance of error with contamination,” said Yvan Bruneau, General Manager at Central Testing Laboratory.

Every week, city officials take 60 water samples from facilities like fire halls and private businesses across the city. Six of those locations tested positive for E.coli, but the lab techs suspect something went wrong in those tests and it can start in the tap.

Bruneau says if the faucet where the water sample comes from is not sterilized or if the bottle and tools the lab is using aren’t clean, false positive tests can occur.

“We do everything in our power to avoid them, so we sterilize all the equipment before we use them,” said Bruneau.

But after a three day, city-wide boil water advisory, the city couldn’t say for sure if it was human error and is now launching an investigation.

“That’s obviously going to be a high priority for us now to deter why that happened,” said Diane Sacher, with the Water and Waste Department for the City of Winnipeg.

But lab experts say it will be almost impossible to find out why the tests came back positive.

“It’s so easy to have a false positive because there’s bacteria everywhere we go,” said Bruneau.

In 2013, what was described by the city as a false positive E.coli test in St. Vital sparked an investigation, but a cause was never found.

“We were not able to determine what happened,” said Sacher.

Bruneau expects the same result this time, “At the end of the day, we’re all human and mistakes do happen.”