WINNIPEG - Officials in Winnipeg are hoping another round of tests expected today will confirm the city's water supply is safe and allow them to lift a boil-water advisory.

The advisory was issued on Tuesday after routine testing found coliform and E. coli at extremely low levels in six of 39 water samples.

Further testing came back clean on Wednesday but regulations require two clean tests in a row before the all-clear can be declared.

Mayor Brian Bowman said the city's experts have concluded it's likely the original samples were false-positives.

Officials said the testing and re-testing was being done as quickly as possible but noted the samples need time to grow in the lab because they are bacteriological tests.

Geoff Patton, acting director of Water and Waste Department, said the same worker took all six of the suspect samples, but what went wrong is still a mystery.