Toronto Major Foundation Drainage Policy Changes Effective October 1, 2026

Toronto is proposing important changes to its Foundation Drainage Policy (FDP) that could significantly reduce construction costs and improve the feasibility of many residential developments, particularly mid-rise housing. If approved by City Council, the changes will take effect on October 1, 2026.

What Is Changing?

Since January 1, 2022, Toronto has generally prohibited long-term discharge of foundation drainage (groundwater collected around below-grade structures) to the municipal sewer system.

The proposed amendments would allow limited discharge of foundation drainage to the storm sewer system, subject to the following conditions:

The receiving storm sewer must discharge directly to a watercourse or Lake Ontario and not connect to a combined sewer system.

  • Groundwater must meet applicable sewer by-law water quality requirements.

  • Maximum dry-weather discharge rates:

    • 2 L/s/ha for sites 0.7 ha or smaller

    • 3 L/s/ha for sites larger than 0.7 ha

Why This Matters for Developers

The current zero-discharge policy has forced many projects to use fully watertight basements and raft slabs (“bath-tubbing”) to prevent groundwater infiltration.

These systems can add approximately $1 million to $3 million to a typical mid-rise project, increasing both construction costs and embodied carbon.

The proposed policy change could:

  • Reduce foundation and structural costs

  • Improve feasibility of mid-rise and affordable housing projects

  • Lower embodied carbon

  • Provide more flexible engineering solutions

Related Sewer By-law Change

Toronto is also considering revisions to the sewer by-law manganese limit, which has historically prevented most projects from discharging groundwater to storm sewers.

This related change is essential to make the policy effective in practice.

Timeline

  • Infrastructure and Environment Committee approval: May 6, 2026

  • City Council decision: May 20–22, 2026

  • Effective date (if approved): October 1, 2026

Insight

This is a significant and positive policy change for Toronto developers. Projects that were previously challenged by costly foundation drainage requirements may become more financially viable under the proposed amendments.

Need Help?

We provide servicing reports, foundation drainage strategies, and municipal approvals support across Ontario. Contact us to assess how these changes may affect your development.