St. Catharines residents are advised, don't panic if you see smoke coming from a manhole near your home.
The city will begin smoke testing sanitary sewers today in an effort to get a better understanding of any issues both above and below ground.
Crews will begin the smoke testing in north St. Catharines today and will move to 14 other neighbourhoods over the next month and a half.
In a release the city says don't worry if you see smoke coming from vent stacks, catch basins, manhole covers or green spaces.
The smoke will not stain clothing, draperies or furniture, and has no known effects on humans, plants or animals.
To avoid smoke entering their homes, residents in the area are advised to run water for one to five minutes in each drain, including infrequently used drains like basement rough-ins.
Water only needs to be run once during the smoke testing period.