Typically, drinking water flows from the City’s distribution system into a property’s private water system. Backflow is the undesired reversal of water flow between the City's distribution system and a private system, due to changes in water pressure. This reversal or “backflow” can cause contaminants to enter into the drinking water distribution system.

Causes of backflow

Backflow can occur due to back siphonage or back pressure.

• Back pressure occurs when pressure in a private water system is greater than pressure in the City’s water supply system, which may be caused by pumps, elevated tanks, temperature increases in boiler systems, and other local pressure events. This can result in water from the private system forcing its way into the City’s distribution system.
• Back siphonage occurs when pressure in the City’s water supply system is lower than pressure in a private system, which may be caused by nearby fire-fighting or water main breaks. This reversal of pressure can pull contaminated water from the private water system into the City’s distribution system.

Types of backflow devices

There are two types of backflow prevention devices (or assemblies) common in achieving premise isolation:

Double Check Valve Assembly (DCVA): Consists of two check valves, which help to provide protection in the event that one valve does not close tightly. Required for facilities classified as “moderate hazard.”

Reduced Pressure Principle Assembly (RP): Consists of two independently acting, internally loaded check valves, separated by a reduced pressure zone. Required for facilities classified as “severe hazard.”

In January 2018 the City will began notifying affected property owners of the requirement to submit an initial survey. Properties with severe risks will be addressed by December 2020, and properties with moderate risks by December 2022. Notification of all property owners will be complete by the end of 2022.

Severe hazard properties

Owners of severe hazard properties have one year to complete a site survey and an additional year to install backflow devices.

• For example: An owner of a severe risk property notified in January 2018 will need to complete a site survey by January 2019 and install a device by January 2020.

Moderate hazard properties

Owners of moderate hazard properties have one year to complete a site survey and two years to install backflow devices.

• For example: An owner of a moderate risk property notified in January 2021 will need to complete a site survey by January 2022 and install a device by January 2024.

Please note:

• Deadlines are based on the date that a property owner receives initial written notification from the City.
• Annual backflow test results for premise isolation assemblies should be filed with Backflow Solutions, Inc. (BSI) Online(link is external) after results of the Survey of Premise Isolation have been provided, or when the property owner has received an annual testing notice from BSI.
• Backflow devices must be tested at the time of installation and annually. Property owners will receive a reminder of their annual testing deadline 30 days in advance.

Request to extend a deadline for survey submission or device installation

• To request an extension, please complete a request form(link is external).

Exceptional circumstances

• Owners of moderate risk properties that require a significant investment in backflow device installations may request additional time to complete the work. Submit a plan by the site survey deadline for review and approval, providing a rationale for the request and demonstrating how installations will be complete by 2027.
• Properties scheduled for demolition within the implementation timelines may be exempt from the requirements. Submit a demolition plan by the site survey deadline for review and approval.

Responsibilities of the property owner

Between 2018 and 2027, based on severity of the hazard, all affected property owners will be required to hire a qualified person to:

• Conduct site surveys every five years to identify risks and report backflow prevention requirements to the City for review. Property owners will receive a reminder to submit an updated survey prior to the deadline.
• Install premise isolation backflow devices to prevent contaminants from entering the City’s water supply.
• Test backflow devices every year to make sure that they are functioning properly and submit the test results to the City for review. Property owners will receive a reminder of their annual testing deadline 30 days in advance.  

Property owners must notify the City within 30 days of any change in hazard level. This could be due to a change in building operations or activities, or any changes in the service connection to the building or property.

Responsibilities of backflow device testers

Testers who have successfully completed the required training with an accredited organization and have a current tester’s certificate will:

• Maintain a current tester’s certificate.
• Pre-register with Backflow Solutions, Inc. (BSI) Online(link is external) to provide information on qualifications and submit annual calibration test data for testing equipment.
• Submit site surveys and test results on behalf of an owner.
• Collect tester and administration fees and submit administration fees to the City of Ottawa.

Responsibilities of the City of Ottawa

The City is responsible for administering the program and complying with the program as a property owner. The City will:

• Oversee administration of the program.
• Inform property owners about the program and their responsibilities.
• Send notifications on site survey and testing requirements.
• Allow testers to register and submit test results on behalf of owners.
• Provide access to owners to be able to review their test data.
• Track the City’s backflow device assets for maintenance and other purposes.
• Collect City administration fees from testers.

Step 1: Initial notification letter from City

The property owner receives a letter instructing to survey the affected property.

Please note: The Backflow Prevention Program asks that the property owners receive initial notification before conducting any work on the property.

Step 2: Hire a contractor

The property owner must hire a contractor (a qualified person, as per the City’s Water By-law) to conduct a Survey of Premise Isolation(link is external) for the affected property.

Step 3: Submit survey results

The contractor (qualified person) submits a Survey of Premise Isolation(link is external) to the Backflow Prevention Program for review.

Step 4: Review of survey and City’s response

The Backflow Prevention Program reviews the Survey of Premise Isolation(link is external). The property owner(s), building contact and the contractor (the qualified person who surveyed the property) receive a response providing at least one of the following instructions:

Notice to Obtain Building Permit

• Apply for a Building Permit through Building Code Services.
• Permit application guidance documentOpens in a new tab or window(link is external) [ 245 KB ]
• Contractor (qualified person) to install the appropriate backflow assembly.
• Annual reporting of test results on the installed backflow device(s) (also referred to “assemblies”) to the Backflow Prevention Program will begin one year after the new device is installed, coordinated through Backflow Solutions, Inc. (BSI) Online(link is external).

Notice to Repair Existing Device(s)

• Contact Building Code Services to confirm if a Building Permit is required before making any repairs. If required, apply for a Building Permit through Building Code Services.
• A contractor (qualified person) to make the required repairs to the backflow device(s) (also referred to as “assemblies”).
• Repeat Step 3, requiring a contractor (qualified person) to submit a new Survey of Premise Isolation(link is external) to the Backflow Prevention Program.

Notice to Test Existing Device(s)

• For existing backflow device(s) (also referred to as “assemblies”) from the submitted Survey of Premise Isolation(link is external), test results are required to be reported to the Backflow Prevention Program by a qualified tester based on the date provided on the survey.

Step 5: Submitting test results for device(s) to the City of Ottawa

Once the Survey of Premise Isolation(link is external) has been reviewed and all necessary action has been taken to install and/or repair devices (also referred to as “assemblies”), the City of Ottawa will begin tracking the annual test results of each device (or “assembly”). Testing must be done by a qualified tester and the results must be submitted to the City of Ottawa through Backflow Solutions, Inc. (BSI) Online(link is external).

Qualified testers must pre-register with Backflow Solutions, Inc. (BSI) Online(link is external) and provide information on qualifications. Testers are also required to submit annual calibration test data for testing equipment.

Request to extend a deadline for survey submission or device installation

• To request an extension, please complete a request form(link is external).