Although many people assume that stormwater runoff is clean, it isn't. Contaminants like hydrocarbons wash off urban surfaces such as roadways, parking lots and rooftops and can harm our rivers, lakes and marine waters. We also waste water when we don't use it wisely. For instance, when we fill a glass, we may run the water to make sure it's cold. It is perfectly clean but once it disappears down the drain, it mixes with sewage and polluted water from other households, businesses and industries.
Wastewater flows through an extensive network of underground pipes into wastewater treatment plants.
For information on what types of sewers there are in the network of underground pipes, click here. In some older parts of the GVRD, wastewater and stormwater are carried in the same pipe. We call these combined sewers . When it rains heavily, the volume of stormwater runoff can become too much for the combined sewers to carry to the treatment plant. As a result, some of the mixed raw sewage and stormwater overflows directly into Burrard Inlet or the Fraser River.