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Combined Sewer Overflows

How Sewer Overflows Work

During periods of heavy rain or snowmelt, older sewer pipes may be too small to handle the water. When this happens, sewage can back up into your basement or overflow into the environment.

There are combined sewer overflows located in both Regional and municipal infrastructure throughout Niagara. Overflows were designed to allow excess water to exit the sewer systems when the pipes could not handle the increased flows due to wet weather and melting snow.

Health and Environmental Concerns

While this system of designed overflows helps to prevent basement flooding, there are health and environmental concerns from releasing under-treated sewage into ditches, rivers and lakes. We're working to reduce and eliminate these overflows.

We no longer install combined sewers, and are working on projects to upgrade existing wastewater treatment facilities to increase treatment capacity, upgrade older sewer pipes and sewage pumping stations.

Municipalities are working at getting downspouts and foundation drains disconnected from the sewer system. These improvements are reducing the volume of combined sewer overflows.

Along with the work being done by Niagara Region and the municipalities, your efforts can also help to ensure combined sewer overflows in Niagara are kept to a minimum.

The proper management of overflows will greatly reduce the potential risk to human health and the environment.

Tips to Reduce Overflows

  • Avoid flushing toilets or running dishwashers / washing machines during heavy rainfall or snow melt
  • Wash your car at a commercial car wash where water is often recycled before released into the sewers
  • Wash your car at home over grass or gravel with a biodegradable soap to allow water to drain into the ground
  • Disconnect your downspouts from the sewer system and let water run onto your lawn
  • Use a rain barrel to collect rainwater from your downspouts. This water can be used to water your plants and grass.
  • Install low flush toilets to reduce water consumption and sewer overflows

Combined Sewer Overflow Control Program

Niagara Region and local municipalities are working together to reduce the amount of inflow and infiltration entering the sanitary system through the Combined Sewer Overflow Control Program.

The cost-share program funds municipal projects to target inflow and infiltration reduction, which helps to reduce basement flooding, overflows to the environment and alleviates system capacity. Some examples of municipal projects funded through the program include:

  • Studies: Targeted investigative work is completed on the sanitary system to assess the condition of infrastructure and to identify sources of inflow and infiltration. Flow monitoring is an example of an important study used to narrow down the location of possible high inflow and infiltration locations.
  • Sewer separation projects: Combined systems are separated by the installation of new storm sewers
  • Overflow storage tanks: Large underground tanks are used to store excess wastewater during heavy rain or snowmelt events. Once the wet weather event is over and capacity in the system is restored, the wastewater is pumped back into the pipes and transported to wastewater treatment plants to be treated.
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