Those in the communities of Lower Sackville, Fall River, Waverley, Lakeview and Windsor Junction are being asked to voluntarily reduce their use of non-essential water.
Halifax Water says crews need to replace about 500 feet of a water main that is failing prematurely along Cobequid Road near Glendale Avenue.
"When the scale of the issue became clear in 2020, we repaired the water main in the most cost-effective way for our customers, but it failed several more times," said the utility in a news release.
"Based on our investigation, we now understand that soil conditions in this area have caused damage to the existing pipe. Now that we have a better understanding of the cause, we are moving quickly to address this issue."
A repair attempt last week cut off water to some customers for several hours.
The replacement work starts today and will continue 24/7 for the next two to three weeks.
At some point, there may be a 48-72-hour window when some might have lower than normal water pressure.
Residents can sign up for updates on the project through Halifax Water's website.
Traffic will be reduced to one lane in each direction and drivers are being asked to avoid the area if possible.
