Construction wastewater and debris must never enter catch basins (square grates on the road). Catch basins connect to storm sewers which drain directly into rivers, streams and Lake Ontario. Allowing construction wastewater or debris to enter the storm sewer can:
- harm fish and wildlife
- pollute rivers, streams and Lake Ontario
- damage the storm sewer system
- cause sewer blockages, which can lead to road and basement flooding
If construction wastewater or debris from your site enters a storm sewer, you may face fines or other enforcement action under the Sewers By-law.
Material That Must Never Enter Catch Basins
- Mud or sand
- Concrete or cement powder
- Vehicle (car or truck) wash water
- Paint
- Oil or petroleum products
- Soap or detergent
- Chemicals
- Construction material, debris or dust
- Construction wastewater
Managing Construction Debris
To prevent debris from entering the storm sewer system:
- wash vehicles off-site at a car or truck wash, or in a designated wash area
- design site entrances and exits that prevent dirt and waste from leaving the site
- This may include gravel, paving, rumble strips and wheel washing.
- do not wash out cement or ready-mix trucks onto roads or into catch basins
- prevent dirt and debris from leaving the site
- do not power wash construction dirt and waste onto roadways or into catch basins
- regularly sweep streets, sidewalks and driveways using dry methods or vacuum sweepers and dispose of waste properly
- keep wash water contained and away from catch basins
- change vehicle oil and antifreeze off-site at approved facilities
- develop and follow an Erosion & Sediment Control Plan
- use measures such as sediment traps, inlet protection, fibre rolls and silt fences to control runoff
- protect nearby catch basins with filter fabric or other approved sediment control measures
- inspect and maintain all erosion and sediment control measures regularly
- properly dispose of all construction debris
Managing Construction Wastewater
Construction wastewater is water that is generated on a construction site. It includes:
- groundwater
- rainwater
- muddy water
- collected water
- runoff water
Construction wastewater must not be discharged into a City sewer system without approval.
If you need to discharge construction wastewater to the sewer system, you must obtain a Discharge Permit or enter into an Agreement with the City. Alternatively, wastewater can be removed by a waste hauler licensed by the Ministry of the Environment, Conservation and Parks.
Discharging construction wastewater or debris to a sewer without authorization may result in fines or other enforcement action under the Sewers By-law.
Date modified: September 9, 2026
