Environmental Monitoring & Protection

Backflow Prevention Program

Backflow is the undesired reversal of water flow against normal direction. Backflow occurs as a result of Back Pressure or Back Siphonage.

Back Pressure occurs when the pressure in a private water system is greater than the pressure in the City’s water supply system.

Back Siphonage occurs when the pressure in the water supply-system is lower than a private-systems’ pressure. This can result in the reversal of flow between the public and private system.

About the Backflow Prevention Program

About the Backflow Prevention Program

The City of Toronto's Backflow Prevention Program works to ensure compliance with the Water Supply By-law and the protection of the drinking water supply.

Backflow Causes

Backflow occurs for one of two reasons: back-pressure or back-siphonage. Get the details.

BFP Program Forms

Download the backflow device test, survey form, and a sample test tag.

Frequently Asked Questions

Learn more about Toronto's Backflow Prevention Program, including why it is important, who it affects, and how to ensure compliance.