Toronto is revising its Foundation Drainage Policy (FDP) in a way that could significantly reduce servicing costs for mid-rise residential developments across the city. The updated policy takes effect October 1, 2026, and introduces conditions under which groundwater discharge to the storm sewer system is now permissible — a departure from the previous requirement to discharge to the sanitary sewer.
What Is Changing
Under the previous FDP, foundation drainage from below-grade structures (parking garages, underground utilities, and waterproofed foundations) was required to be pumped to the sanitary sewer system. For mid-rise projects with significant below-grade areas, this meant designing and installing sump systems with sanitary connections, which added substantial cost and ongoing maintenance requirements.
The revised policy permits discharge to the storm sewer system under specific conditions, primarily:
- A capacity analysis demonstrating available storm system capacity at the point of connection
- Groundwater quality confirmation that the discharge meets storm system acceptance criteria
- A municipal review and sign-off on the proposed connection
Why This Matters for Mid-Rise Projects
The financial impact is significant. Projects with large below-grade footprints — typically 6 to 12-storey buildings with one or two levels of underground parking — have previously faced $1 million to $3 million in additional infrastructure costs related to foundation drainage. These costs included the sump system design, sanitary connection works, and the downstream capacity issues that connection sometimes created.
With storm sewer discharge now permissible (where capacity exists), developers can eliminate or significantly reduce these costs, provided the site's Functional Servicing Report addresses the storm capacity requirements to the city's satisfaction.
What You Need to Do Before October 1
If you have a mid-rise project in the Toronto approval pipeline, review your FSR with your engineer now. Projects submitted after October 1 should assess storm capacity at the proposed connection point early in the process — before the application is filed — so that the drainage strategy is confirmed and defensible at first review.
Projects already under review before October 1 will likely remain subject to the original policy unless the city confirms otherwise. Check with your municipal contact or planning consultant on timing before assuming the new policy applies to your file.
This is a meaningful cost-saving opportunity for Toronto mid-rise developers. The conditions are real and require proper engineering analysis, but for many sites, the storm sewer option will be available and the savings will be substantial.
