Prevent sewer overflows and basement flooding by managing stormwater

Kawartha Lakes – Kawartha Lakes is continuing work to reduce inflow and infiltration, which occurs when stormwater enters the sanitary sewer system.

Sanitary sewers are designed to carry wastewater from homes and businesses to treatment plants. Stormwater from rain and melting snow is meant to flow through a separate stormwater system or soak into the ground. When stormwater enters sanitary sewers, it can overload the system. Too much water in the system can increase the risk of sewer backups into homes, create operational challenges at treatment facilities, increase costs, and potentially impact the environment.

Stormwater can enter the sanitary system through damaged pipes, but the main cause is through illegal connections, such as sump pumps, roof downspouts or foundation drains connected to sanitary sewer pipes.

Planning and prevention

Kawartha Lakes has taken several steps in recent years to address this issue. In 2022, the municipality launched a multi-year inspection program using closed-circuit cameras to identify areas where excess water may be entering the sanitary sewer system. Based on those inspections, infrastructure repairs began in 2023 to fix problem areas.

The municipality also completed a Water and Wastewater Servicing and Capacity Master Plan, which helps guide long-term infrastructure planning and ensures the system can support future growth.

Municipal staff continue to inspect sewer infrastructure and install measures such as rain bladders in manholes located in low-lying areas to prevent stormwater from entering the system during heavy rain events.

How you can help

Residents can also help reduce inflow and infiltration by ensuring sump pumps, downspouts, and foundation drains are not connected to sanitary sewers, and by installing a backwater valve to help protect homes from sewer backups during severe wet weather. In 2025, Kawartha Lakes introduced an incentive to support this work by waiving building permit fees for plumbing changes required to disconnect stormwater sources from the sanitary sewer system.

Reducing inflow and infiltration helps protect homes, lower wastewater treatment costs, and reduce the risk of wastewater overflows to the environment. Learn more about wastewater systems and basement flood prevention on the Kawartha Lakes Utilities, Water and Sewer page.