People in Canmore, as well as Dead Man's Flats, Harvie Heights and at the Canmore Nordic Centre, are being told to boil water until further notice because of high levels of turbidity.
"Residents and businesses in these areas must boil water for at least one minute at a full boil before drinking or using the water for any kind of internal consumption," said a statement by Epcor, the utility company that manages water services in the communities.
Tap water is still safe for washing clothes and bathing, but people should avoid using it for brushing their teeth.
"Consumption of microbiologically-contaminated water may result in illness and stomach flu-like symptoms such as diarrhea, nausea, stomach cramps, and headaches," the Town of Canmore said on its website.
Epcor says it's working to restore the quality of the water and that the advisory will be lifted when that happens.