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Rainwater and Groundwater Impacts

rainwater and groundwater

Rainwater and groundwater in the sanitary sewer system (also referred to as Inflow and Infiltration or I&I) reduces the sewer's ability to carry wastewater. This may cause sewer backups into homes or businesses, or overflows to roads, creeks or sensitive habitat areas. It also means groundwater and rainwater will be sent to the wastewater treatment plant for cleaning, which is unnecessary for this kind of water.

Metro Vancouver requires all local municipalities to limit the amount of rainwater and groundwater in the sanitary sewer system under the Integrated Liquid Waste and Resource Management Plan.

Your Role

Studies have suggested that up to 70% of the rainwater and groundwater in a sanitary sewer system comes from private property.

Help us reduce rainwater and groundwater in the sanitary sewer system by doing the following:

Surrey's Role

The City measures the amount of rain that falls, as well as the amount of water in the sanitary sewer system. We use this information to estimate the amount of rainwater and groundwater in the sanitary sewer system at several locations in the City.

The monitoring results, along with our maintenance program results, help us to identify sanitary sewers with high levels of rainwater and groundwater. The City then decides what actions to take to reduce the amount of rainwater and groundwater in the system.

Related Content

Your Maintenance Responsibilities for Sanitary Sewer

Tips for residents and businesses to keep your sewer pipes working properly.

The City's Maintenance and Rehabilitation Program

Learn what the City is doing to ensure the sanitary sewer system functions properly.