Wet weather sanitary sewer overflows are typically the result of excessive amounts of rainwater inflow and groundwater infiltration entering the sanitary sewer system. Increased frequency and severity of rainfall events—a direct consequence of a changing climate—means both young and older communities are at risk of excessive inflows in their sewer systems. These inflows can occur when roof drain leaders, foundation drains and drainage catch basins are incorrectly connected to sanitary sewers instead of storm sewers. Further, cracks and loose joints in storm sewer laterals can lead to exfiltration into the sanitary system. As climate change makes this a more pressing issue across Canada, one of the challenges in confronting this problem is that losses resulting from excessive inflow and infiltration are frequently misidentified by the public to be exclusively the result of municipal infrastructure failure. In reality, as local officials in Surrey identified, 30 to 70 percent of inflow/infiltration originates from private sewer laterals. That is, problems with sewer connections and laterals on private property have the potential to cause damage to the community as a whole. While owners are responsible for repairing or replacing their sewer connection so no rainwater or groundwater enters the system, the City of Surrey found that a significant and growing volume of rainwater has been entering the sanitary sewer system through private connections. This posed a unique challenge to the local government in Surrey. They had to devise a proactive approach that would inspire private property owners to assess the state of their sewer laterals for the benefit of an entire community. Upon understanding the issue and the obstacles that needed to be overcome, the City of Surrey began to plan out a program that would facilitate the mandatory replacement of private sewer laterals in desperate need of improvement.
In 2008, The City of Surrey took proactive action to combat the emerging, longer-term problem with private sewer connections by introducing a by-law to ensure better maintenance of private sewer laterals (sanitary and storm). As climate change contributes to increased intense rainfall events, excessive water flow can severely limit the capacity of existing sewer systems to serve expanded populations, generate sewer backups, flood basements, impose health risks, increase the operation and maintenance costs of treatment and pumping facilities, and lower groundwater levels leading to detrimental effects on water resources. A particular challenge for local governments involves confronting problems with sewer connections and laterals on private property that have the potential to cause damage to the overall community. Local authorities in Surrey, British Columbia, have come to learn that 30 to 70 percent of inflow and infiltration in sewer systems originates from private laterals. The City took early action to confront this problem with a by-law that introduced several triggers that would lead to the mandatory replacement of sewer laterals in Surrey. Central to the approach of the by-law was the focus on properties choosing to undergo significant renovation or redevelopment. The by-law used redevelopment valued at greater than $100,000 as a trigger for the assessment and potential replacement of private sewer laterals. This made the improvement of private sewer connections one element of a larger renewal process. Requiring all homeowners to change their sewer laterals would be impractical, but having property owners assess the state of their laterals during a time of significant investment in renewing their homes was an effective, proactive approach to this issue. The by-law has not been challenged since its implementation, but the City is looking to revise components of the by-law to provide an exemption for property owners required to conduct major unplanned renovations due to circumstances out of their control – extreme weather events for example.