2024 Ontario Building Code (OBC) Guide: Backwater Valves and Drainage Systems in London, Ontario
Sarah's Expert Insight
OBC Compliance Specialist
"In areas like London and Oakville where heavy rainfall can cause municipal sewer surcharges, the correct installation of 'normally open' backwater valves is the most critical defense against basement flooding. As a senior consultant at empcontracting.ca Inc. your construction contractor in London, Ontario, I emphasize that following these 2024 OBC standards isn't just about compliance; it's about protecting the structural integrity and insurance eligibility of your home."
Understanding the 2024 Building Code Compendium is vital for any major renovation or new build. At empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure every project adheres to Section 7.4 requirements to protect your property from water damage and sewage backflow.
OBC 7.4.7.1: Standards for Backwater Valve Installation
Backwater valves are essential for preventing sewage from entering a home during a municipal sewer surcharge. The OBC mandates specific requirements for these devices:
Normally Open Design and Material Compliance
A backwater valve may be installed in a building drain provided it is a 'normally open' design. This valve must conform to CAN/CSA standards for materials such as Cast Iron (B70), ABS (B181.1), PVC (B181.2), or Plastic (B182.1). Crucially, a single valve cannot serve more than one dwelling unit.
Mandatory Backflow Protection
The code requires backwater valves to be installed on every fixture drain located below the level of the adjoining street. In residential buildings served by public sanitary sewers, these valves must protect any fixtures situated below the upstream sanitary manhole cover to prevent catastrophic flooding.
7.4.7. Cleanouts for Drainage Systems
Maintenance accessibility is a core requirement of the 2024 OBC. Sanitary and storm drainage systems must include cleanouts that allow for the cleaning of the entire system.
Required Cleanout Locations
- Upstream side and directly over every running trap.
- At the bottom of interior leaders (or within 1 meter upstream).
- For building sewers NPS 8 or larger, a manhole must be used as the cleanout point.
7.4.6.5. Specialized Sewer Services
For mobile home sewer services, the code requires an NPS 4 minimum pipe size, above-ground termination, and specific protections against frost heave and tampering using concrete pads and engineered design practices.
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.