Backflow Prevention Program

Backflow Prevention

How to prevent backflow

The Ontario Building Code mandates that the potable water system must be protected from backflow.

Principles of providing protection

The determination of an appropriate device to provide efficient protection depends on the following considerations:

Severity of hazards: Severe, Moderate or Low

  • Severe Hazard

    Any connection or potential connection that involves water that has additives or substances that, under any concentration, can create a danger to health.

  • Moderate Hazard

    Has a low probability of becoming a ‘severe hazard’. The water’s aesthetic qualities have been further reduced, and under certain conditions, may create a danger to health.

  • Low Hazard

    Any connection or potential connection that involves a substance which has reduced the water’s aesthetic quality, this could involve water that has been heated or cooled. Generally these hazards are a nuisance only, and upon consumption pose no danger to health.

How to choose a premise isolation backflow prevention device

The following backflow prevention devices can provide premise isolation protection. More detailed guidelines are listed in the "Manual for the Selection and Installation of Backflow Prevention Devices" (CAN/CSA-B64.10), which is published by the Canadian Standards Association.

  • Double Check Valve Assembly, which protects up to moderate hazards and protects against both back-siphonage and back-pressure
  • Reduced Pressure Principle Backflow Prevention Assembly, which protects up to severe hazards and protects against both back-siphonage and back-pressure

Isolation by a Double Check Valve Assembly (DCVA)

Examples of buildings or facilities (not an all-inclusive list) that can be isolated by a DCVA are:

  • Hair Salons;
  • Apartment or office buildings (high-rise);
  • Restaurants;
  • Swimming pool facilities;
  • Any facility with a ‘moderate’ hazard classification;

Isolation by a Reduced Pressure Principle Backflow Prevention Assembly (RP)

Examples of buildings or facilities (not an all-inclusive list) that shall be isolated by a RP are:

  • Chemical or plating plants;
  • Commercial laundries;
  • Automotive Body Shops;
  • Food and beverage processing plants;
  • Hospital, operating, laboratory, or mortuary facilities;
  • Any facility with a ‘Severe’ hazard classification;

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