OBC Backflow Prevention & Back-Siphonage: 2024 Ontario Building Code Guide
Sarah's Expert Insight
OBC Compliance Specialist
"As a senior consultant at empcontracting.ca Inc. your construction contractor in London, Ontario, I emphasize that matching the correct backflow preventer to the specific hazard class is non-negotiable for passing municipal inspections. Whether we are retrofitting a commercial property in London or a luxury cottage in Muskoka, ensuring your fire and plumbing systems meet the latest CSA B64.10 standards is the only way to protect your potable water and your liability."
Understanding the 2024 Ontario Building Code (OBC) plumbing regulations is essential for maintaining water safety and project compliance. Section 7.6.2 outlines the requirements for protecting potable water systems from contamination through back-siphonage and backflow.
7.6.2.2. Requirements for Back-Siphonage Protection
In Ontario, every potable water system that supplies a fixture or tank not subject to pressures above atmospheric must be equipped with a backflow preventer. This is particularly critical for:
- Boilers and cooling jackets
- Lawn sprinkler systems
- Tanks where water outlets may be submerged in non-potable fluid
7.6.2.3. Compliance with CSA B64.10 Standards
Backflow preventers required under this subsection must be selected, installed, and tested in strict conformance with CSA B64.10, 'Selection and installation of backflow preventers.' This ensures that devices like tank-type water closet valves function correctly to prevent siphoning non-potable water back into the main supply.
7.6.2.4. Backflow Prevention in Fire Protection Systems
Fire suppression systems present unique risks for water contamination. The OBC categorizes these requirements based on the system type:
- Residential Full Flow-Through Systems: Typically do not require backflow preventers if using potable-grade materials.
- Partial Flow-Through Systems: Require a dual check valve backflow preventer conforming to CSA B64.6.
- Class 1-3 Systems: Requirements vary from single check valves to double check valve backflow preventers (DCVA) depending on the presence of additives or antifreeze.
- High-Hazard Systems (Class 4 & 5): These must be protected by a reduced pressure principle (RP) backflow preventer to ensure maximum safety against chemical or biological contaminants.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.