This testing is performed by blowing a harmless vapour into a sewer. The “smoke” is not a real smoke, but rather a mist containing a large percentage of moisture. It is highly visible at low concentrations. The smoke is expected to exit from manholes, the sewer stack at the top of your house, catch basins and downspouts.
The City will deliver notices to buildings within the testing area and will inform the local fire and police departments of where they will be conducting smoke testing each day.
Smoke may be seen coming out of the ground, manholes, or sewer stacks and gutters on homes and businesses. Smoke coming out of the ground may indicate a break or other defect in the sewer line that allows smoke to escape up through the ground. For instance: if smoke permeates up through a yard, it indicates breaks in the sewer line.
Only enough force to overcome atmospheric pressure is required, and smoke should escape from building sewer stacks.