Backflow Prevention


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Back Flow Prevention

To protect the safety of drinking water supplies from cross-contamination, many municipalities have passed bylaws implementing requirements and controls around cross-connections with that municipality’s water distribution system.

Climate Works performs surveys, installs, consults, inspections, and maintenance of back flow preventers. If you require help with backflow or are required to achieve compliance with legislation, we are here to help.


The city of Ottawa backflow prevention bylaw came into effect on June 28, 2017. While the majority of drinking water consumers will not fall under the purview of this bylaw, over 15,000 industrial, commercial, institutional, and multi-residential properties currently are. If you are impacted, you will have received a letter from the city requesting that a survey be completed, beginning the journey to compliance.

If you have received a letter, you can contact Climate Works. We will walk with you, through the steps to compliance and safer drinking water. While there are multiple timelines for different buildings, the first set will require action by December of 2020.

The steps involved are:

  1. You receive a letter from the City requesting a survey be completed, at this time we will begin our engagement. Contact Climate Works to conduct a survey,
  2. Climate Works completes the survey and submits it to the City of Ottawa,
  3. You receive a letter form the city stating what is required of you,
  4. An Engineer will need to be engaged at this time to design the backflow prevention system. Climate Works can recommend various engineers or you can use your preferred engineer,
  5. Climate Works can provide a price based on the engineers drawings,
  6. Climate Works installs the system and certifies it,
  7. You are now compliant with the City of Ottawa bylaw

Testing of backflow devices must be conducted annually, with surveys to be completed every 5 years. If a property owner does not comply within indicated timelines, a notice will be issued providing for a 30 day window in which to reach compliance. Failing to reach compliance may result in fines ranging from $500 to $100,000 per day, with potential to have the water supply turned off.


Under the Water Supply By-law, it is mandatory for property owners of industrial, commercial, institutional, and Part 3 residential properties (defined by the Ontario Building Code, as amended) to install backflow prevention devices on their water supply lines. Construction sites must also comply.

The backflow device required by the building or site in question will be determined by their hazard level, as defined by their classification under Schedule 5 of the Water Supply By-law. The City of Toronto recommends that you contact Toronto Water should you require assistance in determining the correct device for your facility.

The City of Toronto requires that management must follow certain requirements. These include how to manage records, report tests, and who may conduct work or produce reports. For examples, testers must be certified as Cross Connection Control Specialists. Functions requiring authorization can be found detailed, in-depth, in Schedule 6 of the Water Supply By-law.

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    What Is a Backflow Preventer?

    A back flow preventer is a device installed at the water supply line, where it enters your building. The device only allows water to flow into the destination system and not back out to the source, preventing contamination of the source system by contaminants in the destination. While these systems are not required in all municipalities, they do safeguard the local drinking water system, and we recommend they be installed where possible.

    There are two types of backflow prevention systems, with the type required for the building mandated by the local water supply by-law and related to the severity of the risk of backflow.

    Double Check Valve Assembly (DCVA)

    Consists of two check valves, which provide redundant protection in the event that one valve does not close fully. These valves must be tested at least annually, as they may fail without visible warning. Typically these are chosen for buildings with less severe risk profiles.

    A Double Check Valve Assembly
    A Double Check Valve Assembly

    Reduced Pressure Principle Assembly (RP)

    Consists of two independent, internally loaded check valves, separated by a reduced pressure zone. These devices must also be tested annually, and must be installed in an area with adequate drainage.

    A Reduced Pressure Principle Assembly
    A Reduced Pressure Principle Assembly

    What is backflow?

    Under normal circumstances, drinking water flows from the source (the municipality) water supply system into a private system. When the pressure in the source system is not equal to that of the private system, water can leave the private system and re-enter the source. This reversal of the norm can cause contaminants to enter into public drinking water system. Backflow may either be caused by back pressure or back siphonage, both related to differentials in pressure between supply and consumer.

    Back Pressure

    Back pressure occurs when the pressure in the destination system is greater than the pressure in the source, and can be caused by either design or changes to the operation of the destination system. Pressure events can be caused by things as simple as temperature increases in boiler systems, or could be related to elevations or installation of pumps.

    Back Siphonage

    Back siphonage occurs when the source water supply system has a lower pressure than the destination system. Contaminated water can therefore be pulled from the destination system, into the source. Typically this is caused in incidences where there is a great demand on the source system, such as when a watermain breaks or firefighters are fighting a fire in the area.


    There is a system out there for you, and we are here to help you find it. Climate Works Heating, Cooling & Plumbing Installs, Services, and Maintains all types of Commercial & Industrial Plumbing Equipment. We are TSSA Certified and our licensed technicians are experts when it comes to gas, oil, propane, hydronic and electric equipment. We Are Your Commercial Plumbing Experts.