The sanitary waste system takes wastewater discharged from toilets, sinks and other household plumbing through municipal sewer pipes to a treatment facility. Independent (i.e. separated) waste and stormwater sewer systems have been municipal best practice for new developments for the past six decades. However, before current practices were adopted, the homes were serviced with a combined sewer system to carry both sanitary waste and stormwater. These combined systems are proving to be outdated, as they are designed to discharge untreated sewage into local waterbodies during intense precipitation events—compromising stormwater runoff quantity and quality, and threatening fish habitats. Homes connected to combined sewers are also prone to damage from the backup of sanitary wastewater. In Metro Vancouver, the largest impact of climate change is expected to be increased frequency and severity of intense rainfall events. This made it crucial for the region to assess vulnerabilities and devise a plan that improved stormwater management by replacing outdated combined sewer infrastructure. Member municipalities of Metro Vancouver combined efforts with provincial and federal environmental agencies to form the Stormwater Interagency Liaison Group in 2002. The organization conducted research related to stormwater management and analyzed long-term rainfall records and climate scenarios to gain a better understanding of risk levels which would inform adaptation actions and their timelines. It was to map out which municipalities had the highest percentage of combined sewers in the region. Combined sewers are less common in Greater Vancouver than in many other large, older cities in North America, which made the task of replacing these systems more feasible.
In 2002, several environmental goals for Metro Vancouver were set under the Liquid Waste Management Plan to combat an expected increase in frequency and severity of intense rainfall events due to climate change. It was considered crucial for the Metro Vancouver area to improve stormwater management by replacing all combined sewer systems with separated sewer systems. Combined sewer systems are designed to discharge untreated sanitary waste into local receiving waterbodies during intense precipitation events, which are ever-increasing due to climate change. Metro Vancouver sought to eliminate the discharge of such pollutants, which threatened fish and their habitat by negatively impacting water quantity and quality. Metro Vancouver and its member municipalities formed the Stormwater Interagency Liaison Group in 2002 to facilitate the coordination of common research related to stormwater management. Sewer studies were initiated that analyzed long-term rainfall records and climate change scenarios. Metro Vancouver launched multi-year sewer separation programs that involved replacing all combined sewers by 2075. While the area has made significant infrastructure improvements, a major challenge that emerged involved addressing sewer laterals on private property. Private sewer laterals seldom receive any maintenance or inspection after their initial construction and most property owners were unaware of the condition of their sewer connections. Metro Vancouver municipalities are considering implementing by-laws that would use the time-of-sale of a home or a property transfer as a triggering circumstance for requiring the rehabilitation of private sewer laterals.