Backflow Prevention Program and By-law FAQs


Municipal Office

395 Mulock Drive P.O. Box 328 Station Main, Newmarket, Ontario
L3Y 4X7

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For more information about the Backflow Prevention Program and By-law, send us an e-mail at:

Is this program related to basement flooding and installation of backwater valves on sewer lines?
No. The Town’s Backflow Prevention Program deals with protecting our drinking water. This program is not to be confused with backwater valves that are placed on sewer lines to prevent basement flooding.
Why is a Backflow Prevention Program Needed?
The Town’s Backflow Prevention Program will protect our drinking water from Cross Connections which may cause the drinking water to become contaminated. It is another step in ensuring that our drinking water quality continues to be of the highest standard and safe for consumption. The backflow prevention program is also necessary to meet the requirements of the Safe Drinking Water Act, 2002, the Ontario Building Code (OBC) and the Canadian Standards Association (CSA) B64.
What is a Cross-Connection?
A cross-connection is any temporary or permanent connection between a public water system or consumer's potable water system and any source or system containing non-potable water or other pollutants or contaminants. Cross connections pose a hazard to the drinking water system if backflow occurs and contaminated water from a building is drawn back into the drinking water system. An example of a cross connection is the connection between a public water system or consumer's potable water system and a heating or cooling system, fire system or irrigation system, etc.
What is Backflow?
Backflow is defined as the undesired reversal of drinking water flow within a plumbing system. When flow reversal occurs, the unprotected cross connections to the drinking water system have the potential to draw or force back pollutants or contaminants into the drinking water piping and ultimately the Town’s drinking water distribution system. This results in unsafe conditions at the property and places the Town’s drinking water system and the community’s safety at risk.
What Causes Backflow?
There are two causes.

Backpressure: Occurs when the pressure within a building’s plumbing system is greater than the pressure in the drinking water system. This results in the water within that building being forced backward and into the Town’s drinking water system. These situations can occur in cases such as high rise buildings as a result of increasing pressures to pump water to the upper floors or from pumps within the process at industrial buildings.

Back Siphonage: Occurs when the pressure in the drinking water system is decreased due to a negative pressure resulting in the water within the building to be sucked back into the Town’s drinking water system. The low pressure condition can be caused by a watermain break, hydrant flushing operations or firefighting operations, to name a few.
How often does backflow and contamination of the drinking water system happen?
The opportunity for backflow occurs fairly often whenever there is a difference in pressure between the private system and the Town’s drinking water system. The occurrence of major contaminants entering the drinking water system is less frequent but can happen at any time when there is backpressure or back siphonage and no backflow prevention device installed.
What Properties does the Backflow Prevention Program Apply to?
This program applies to all industrial, commercial, institutional and multi-residential and mixed use buildings. It also applies to any property, including residential, that poses a risk to the quality of the Town’s drinking water and safety of our community, regardless of the property class.
How does this program apply to Townhouses?
This program does not apply to townhouses where there are individual water services to each townhouse from the Town’s drinking water system. However, in cases where there is a single water service line from the Town’s drinking water system for the entire subdivision, backflow prevention will be required.
Would any buildings be exempt or grand-parented under the program?
There will be no exemptions or grand-parenting.
What is the definition of a Multi-Residential Building?
A “multi-residential building" means a residential building that consists of more than five (5) self-contained residential dwelling units, but does not include buildings that only consist of residential single-dwelling units that are solely attached to other residential units on the sidewall (such as semi-detached homes, townhomes or row houses) or single-dwellings that contain basement apartments or annexes.
Who is Responsible for meeting the Backflow Prevention Program Requirements?
The owner of the property or agent of the owner or the condominium corporation.
What are my responsibilities as the property owner to comply with Backflow Prevention Program By-Law?
The owner of the property or agent of the owner must ensure that the following activities are performed, and reports submitted to the Town within the timelines indicated in Schedule B of the by-law:
  • Undertake a Cross Connection Control Survey for each service connection at every property you are responsible for and submit the report to the Town. These are required every 5 years or when there is a change in ownership or property use.
  • Install Backflow Preventers on each service connection where required.
  • Test Backflow Preventers upon installation and annually thereafter for Severe and Moderate Hazards and every five years for Minor Hazards.
  • Undertake corrective actions identified in Cross Connection Control Survey Report and the Backflow Prevention Device Test Report
  • Ensure that the work is performed by qualified personnel as required under the by-law. Owners will be responsible for all costs related to backflow prevention at their properties
Owners will be responsible for all costs related to backflow prevention at their properties.
Will there be Administration Fees?
Yes, there will be administration fees which will be listed in the Town’s schedule of Fees and Charges.
Will there be one submission date for everyone?
There is a deadline of February 29, 2020 for everyone for the initial Cross Connection Control Surveys. However owners can choose to submit them earlier which will determine the 5-year anniversary date for submission of future surveys. The recommendations from the surveys will determine if a device is required. The device installation date would be the anniversary date when the test report would be due.
What are the consequences of not complying with the requirements of the Backflow Prevention Program?
Compliance will be monitored by the Town’s Water Services. Enforcement will range from reminders and notifications to fines, penalties and disconnection of the water supply to the subject property if necessary.
What is a Backflow Preventer?
A Backflow Preventer is a mechanical device that prohibits backflow of water into the public drinking water system. Backflow preventers are typically installed on the private properties immediately downstream of the water meter. The main types of Backflow Preventers are a reduced-pressure principle assembly, a pressure vacuum breaker assembly, and a double check valve assembly. Examples of a secondary type of device are hose connection vacuum breakers and residential dual check valves.
What is Premise Isolation?
The Backflow Prevention Program requires isolation of the private plumbing system from the Town’s drinking water distribution system by installing a backflow preventer. This is referred to as Premise Isolation.
Where Should I Install the Backflow Preventer?
The typical location for installation is immediately downstream of the water meter and upstream of any irrigation connections. The precise location must meet the requirements of the OBC. A building permit must be obtained from the Town’s Building Services prior to installation. If you have a unique situation where locating the backflow preventer may be difficult then you are encouraged to contact Water Services to discuss your situation.

Although the Town’s Backflow Prevention Program requires only Premise Isolation, installation of preventers within zones, areas and at sources within the private plumbing system, must be carried out if identified as a “corrective action” by a qualified person in a cross connection control survey or test report.
Will the water pressure be reduced within the private plumbing due to the installation of a premise isolation backflow preventer?
Yes. The installation of a backflow preventer will reduce the water pressure within your facility. Please consult with the contractor to ensure that there will be adequate water pressure for your processes after the backflow preventer is installed.
Where can I obtain the required forms?
Click on the Forms link to obtain the most recent versions of the respective forms, and use them for the surveys, tests and corrective actions you are conducting.
Why do backflow preventers need to be tested periodically?
Backflow preventers have internal parts that can wear and tear, so they must be tested periodically, by qualified persons, to ensure they are working properly.
Is a Building Permit Required to Install the Backflow Preventer?
Yes. The installation must meet the requirements of the OBC so a building permit must be obtained from the Town’s Building Services prior to installation. For additional information on the building permit application please contact the Town’s Building Services.
Who is authorized to perform the work required for the Backflow Prevention Program?
Only those persons with the required qualifications listed in the Authorized Functions List, attached as Schedule "A" to the by-law may carry out the corresponding functions shown. Persons performing Cross Control Surveys and Testing of Backflow Preventers must have a current and valid Tester’s Certificate issued by the Ontario Water Works Association (OWWA). They must also have a valid calibration certificate for their testing equipment. Please refer to the by-law for details.
What are the estimated costs to property owners?
The initial cost would depend on the fees charged by a qualified person to undertake the survey, install the backflow preventers and perform the tests. The backflow preventer cost would depend on the type of device recommended for installation and the location. Once the device is installed and tested, the cost to the owner would be the annual cost of testing and any required repairs.
Will there be incentives or rebates to property owners?
No. The program is mandatory to ensure that the Town’s drinking water remains safe for consumption.