A precautionary boil water advisory has been issued for an area that overlaps the Côte-des-Neiges and Outremont neighbourhoods.
The advisory is in effect until further notice. It affects about 25,000 people.
The affected area includes a sector bordered by Décelles Avenue, Bates Road and de la Côte-Sainte-Catherine Road.
Anyone in the area should boil tap water vigorously for one minute before drinking it.
Work on a watermain in the Édouard-Montpetit Boulevard area led to a reduction in water pressure, prompting the advisory.
Tap water that has not been boiled can still be used for bathing and cleaning.