Most of Lachine is under a boil-water advisory after a water main break put the traffic to a halt earlier this morning.
The borough of Lachine has since issued an update asking residents to boil their water for at least one minute before consuming.
The borough sent out the warning on Tuesday morning, through a tweet and a Facebook post.
Authorities say a 30-inch pipe broke overnight and led to the closure of a tunnel between Highway 13 and Highway 20.
The advisory applies to the whole sector except for the neighbourhood of Saint-Pierre. Montreal Mayor Valérie Plante is asking drivers to avoid the area near Provost Street and Highway 20.