Toronto's Sewer System

Within Toronto's sewershed, small diameter pipes join up to larger diameter pipes and finally to sewer mains, which connect either to treatment plants or nearby rivers or streams, (depending on the type of sewer).  The oldest pipes in Toronto are wooden, although most of these have been replaced with steel, plastic or concrete pipes.

Combined sewers have not been built in Toronto since the 1950s, but are still present in many older sections of Toronto.  The City has begun a "Combined Sewer Elimination Program" aimed at installing stormsewer pipes beside existing combined sewers. After the new stormsewers are installed, they will carry only stormwater and snowmelt and the old combined sewer will handle only sanitary sewage, eliminating the overflow in wet weather.