Every year, selected neighbourhoods have their main sewer lines cleaned. This maintenance is done to make sure the pipe is functioning normally.
The pipes are cleaned using high-pressure water and then are scoured as the equipment is pulled back through the pipe. Any debris is pulled back with the water and is removed using a vacuum truck.
During the cleaning process, air occasionally vents through the sewer pipe and may enter into homes in the area. When this happens, water in the toilet bowl or floor drains can temporary bubble or surge. In rare cases water may splash out of the toilet bowl or drain.
Neighbourhoods are selected based on the condition and age of the underground pipes. Some areas have their pipes flushed quarterly.