Dye testing is a simple, safe, and effective way for the city to identify issues within the sewer system, such as cross-connections, leaks, or damaged pipes. These issues can allow wastewater and rainwater systems to mix, which can impact the environment and increase the risk of flooding or sewer backups.
The City operates two separate sewer systems:
- Sanitary Sewer: Collects wastewater from your toilets, sinks, and washing machines and carries it to a treatment plant.
- Storm Sewer: Collects rainwater and groundwater runoff and directs it to local waterways without treatment.
Dye testing helps confirm that these systems are working as intended.
In some cases, stormwater sources—such as roof downspouts, driveway drains, or yard drains—may be incorrectly connected to the sanitary sewer. This can overwhelm the system during heavy rainfall.
Dye testing helps identify these issues so they can be corrected, reducing the risk of sewer backups, flooding, unnecessary strain on infrastructure and pollution entering local waterways.
This type of testing is widely used because it clearly shows how water moves through the system and helps pinpoint problems quickly without excavation.
How Does the Test Work?
Dye testing is a straightforward, non-invasive process that allows crews to trace the path of water through the system.
- Dye Introduction: Staff introduce a small amount of non-toxic, biodegradable, brightly colored dye into a specific drain or outlet.
- Tracking: The dye moves through the system along with water. Staff monitor nearby pipes, catch basins, or manholes to observe where the dye appears.
- Identification: If the dye appears in an unexpected location—such as the sanitary sewer from a downspout, or in a waterway—it indicates a potential cross-connection, leak, or pipe defect that may need repair.
What to Expect
- Safety for People and the Environment: The dyes used are non-toxic, water-soluble, and environmentally safe.
- Access to Property: City crews may require access to outdoor areas of your property. Access inside your home is typically not required.
- Visibility: You may notice brightly coloured water (often green, red, or yellow) in nearby catch basins, ditches, or waterways. This is expected and is part of the testing process.