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October 14, 2008
Toronto's deadline for installing backflow prevention devices is approaching
On January 1, 2008, Toronto’s new Water Supply Bylaw came into effect. The bylaw includes improvements for the protection of Toronto’s water distribution system and harmonizes all previously existing bylaws into one.

One of the targets of the new bylaw is eliminating the backflow of potential contaminants into the water supply system. Backflow is the undesired reversal of water flow against normal direction. There are two causes of backflow: backpressure and backsiphonage. Backpressure occurs when the pressure in a private water system is greater than the pressure in the City’s water distribution system. If this happens, water from a private water system can force its way into the water distribution system. Backsiphonage occurs when there are dips in pressure in the water distribution system. Common causes for backsiphonage are watermain breaks and water use for firefighting.

To comply with the province’s Safe Drinking Water Act, the City’s new bylaw is enforcing mandatory installation of backflow prevention devices for industrial, commercial and institutional properties and multi-residential properties (five or more units) to prevent chemicals, pollutants, toxic substances, bacteria, pathogens, and non-potable water from entering the city’s water supply. Owner/operators of these types of buildings are legally required to install backflow prevention devices on all connections coming off the City’s water distribution line. This is in addition to any other backflow prevention devices installed on individual units within a building.

There are two types of backflow prevention devices that can be installed based on the building’s hazard level. The hazard levels for each type of industry are outlined in Schedule 5 of the Water Supply Bylaw. Only a certified installer, with an Ontario Water Works Association Certification in Backflow Prevention can install backflow prevention devices (for installer requirements, go to: Property owners are responsible for hiring certified installers and following the device testing schedule. Prior to beginning installation of backflow prevention devices, a Toronto Building permit must be obtained.

These are the compliance dates for industries, based on their risk level:
• manufacturing industries rated as a severe risk: December 31, 2008
• commercial operations rated as a severe risk: March 31, 2009
• industries rated as a moderate risk: June 30, 2009.

For more information about the Toronto Water Supply Bylaw or to download a copy, visit our website at: or call our voice mail system 416-394-8888 or

Toronto is Canada’s largest city and sixth largest government, and home to a diverse population of about 2.6 million people. It is the economic engine of Canada and one of the greenest and most creative cities in North America. In the past three years, Toronto has won numerous awards for quality, innovation and efficiency in delivering public services. Toronto’s government is dedicated to prosperity, opportunity and liveability for all its residents.

Media contact:
Cheryl San Juan, Senior Communications Co-ordinator, 416-392-8259,



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