The Winnipeg Regional Health Authority is asking south St. Vital residents to take precautions with their tap water, as a boil water advisory is in effect there.
Lisa Richards, WRHA medical officer of health, said Tuesday so far there have been no reports of illness, but that is still a possibility.
"We are quite concerned about e-coli in the water because it can cause significant illness including diarrhea and vomiting.And then in very rare and severe circumstances, it can cause kidney damage."
The precautionary boil water advisory issued Tuesday evening is for a "localized area of southeast Winnipeg."
The affected area is south of Bishop Grandin Boulevard to the Perimeter Highway, and east of the Red River to the Seine River.
Richards said the results also explained why there have been no illnesses reported.
"I think the good news is what we call the chlorine residuals, or the amount of chlorine in the water in that area was sufficient or enough to kill any bacteria in the water."
Residents in the affected area should boil their tap water for at least one minute before
- using it for drinking,
- making ice,
- preparing food and beverages such as infant formula
- brushing teeth.
The city says residents don't have to boil their tap water for washing clothes or dishes.
Adults and older children are advised to avoid swallowing the water while taking a bath or shower, while young children should be sponge-bathed.
Officials said more samples have been taken from the area and preliminary test results are expected Wednesday afternoon.
The WRHA says the positive test result, which came from a routine set of water samples collected on Monday, may have been produced by a sampling error.
Positive test results do occur sometimes but they have always turned up negative in subsequent tests, officials said.