Shoppers at this Sobeys in Winnipeg's Sage Creek area were snatching up bottled water Tuesday night after a boil-water advisory was issued for the entire city of Winnipeg. (Cameron MacIntosh/CBC) The city of Winnipeg's nearly 700,000 residents are under a boil water advisory Tuesday night after tests confirmed the presence of E. coli in the city's water supply.

The Winnipeg Regional Health Authority (WRHA) originally said in a press release the advisory was for an area east of the Red River.

The release said the advisory was being issued "as a precautionary measure as a result of two clusters of positive results involving the presence of E. coli, received earlier today."

"There St. Boniface General Hospital stopped using city water around 6:30 p.m. and began handing out bottled water to patients. has been no source of contamination identified to date; however, public health is proceeding according to provincial and national guidelines. These guidelines specify to issue the advisory as a precautionary measure, while investigating the possible causes."

The city will be holding another press conference at 7 30 a.m. Wednesday morning to provide an update on the boil water advisory.

The WRHA said there haven't been any suspicious cases of illness to date related to the city's water.

"E coli is an 'indicator' of water contamination that we measure, and there are many other types of bacteria in water that could cause illness. However, a high amount of chlorine has been found in the same water samples measured yesterday, which is reassuring because this would suggest that any bacteria or viruses present in the water would likely be killed," according to a release from the WRHA.

At a news conference around 6 p.m. CT, the city revised those concerns and has now extended the advisory across the city.

"In an abundance of caution, the City of Winnipeg has decided to proactively issue a precautionary boil water advisory for the entire City of Winnipeg," read a statement from the city.

Engineers with the city said results for six suspect water samples arrived Tuesday from tests run on Monday. Five of the samples came from areas east of the Red River, while another came from southwest Winnipeg.

Winnipeg residents have been advised to boil all water for at least one minute before doing any of the following:

Drinking and ice making

Beverage preparation, such as infant formula

Preparing food

Brushing teeth

The St. Boniface General Hospital switched to bottled water for patients around 6:30 p.m.

As for schools, several were using social media Tuesday night to let parents and students know drinking fountains would be turned off. Parents were advised to pack either boiled or bottled water for their kids Wednesday, as all schools in Winnipeg will be open.

And in stores around Winnipeg, bottled water sales skyrocketed into the evening to the point where many store shelves were empty by 9 p.m.

Shoppers like Krista Surowich were grabbing water supplies before they were gone at the Main Street Co-op.

"Some were $7.49 a pack. I just grabbed whatever I could. I just left a couple. There's not very many on the shelves any more," said Surowich.

Surowich said she drinks five litres of water a day and it's better to be safe than sorry.

The advisory will be in place until Wednesday afternoon, when the city expects more test results to arrive.