What the City currently publishes
The City says all new single, semi-detached, row-house and townhome dwelling units require backwater valves on sanitary service laterals. For the installations covered by its page, the City describes an inspection confirming a normally open valve on the sanitary building drain, located within the dwelling unit and accessible for inspection and maintenance.
- The City references Ontario Building Code Division B, section 7.4.6.4.2 and referenced standards.
- The page says permit plans and specifications should be available to the building inspector at inspection.
- The City advises booking an inspection 48 hours in advance on that page.
Do not assume the same steps apply to a retrofit
The published page focuses on permit and inspection information, including new construction. It does not make this page a determination for every existing home or retrofit. Ask the City or the permit authority which application, review and inspection steps apply to your exact scope.
- Describe the property, plumbing work and whether this is new construction or a retrofit.
- Ask what drawings, forms and records are required.
- Keep the City's answer and approved documents with the project file.
Official references
Source pages checked September 24, 2026. Re-check official guidance before acting.
If you want help thinking it through
Bring your questions, not a script.
A request is not a commitment. Share the home context you know and we will keep the next step clear.