Vancouver’s rainwater-management requirements depend on the project, site area, floor space ratio (FSR), and permit pathway. The city’s current guidance also identifies a 2026 transition for engineered-pathway applications. A general statement that an ADU is allowed or a property is connected to sewer does not settle which requirements apply to the site.
First confirm the project is within scope
Vancouver says most new buildings must provide on-site rainwater management. The city’s published exceptions include accessory buildings and laneway houses or infill added to a site with an existing building when the site is no greater than 1,000 m². The city says the engineered pathway applies to the latter group when the site is larger. Verify how the bylaw defines the proposed building and existing-site condition before assuming an exemption.
For projects subject to the requirements, the city describes two pathways:
| Published site/project condition | Pathway described by Vancouver |
|---|---|
| Up to 1.0 FSR and site area up to 1,000 m² | Small-site pathway, subject to listed exclusions |
| More than 1.0 FSR, site area greater than 1,000 m², or both | Engineered pathway |
The city says FSR is calculated under the Zoning and Development By-law, after applicable exclusions. A parcel’s area and project floor space therefore need to be checked against the official definitions and current records.
Small-site storage figures
For the small-site pathway, Vancouver publishes these minimum active storage capacities and orifice plate diameters:
| Site area | Minimum active storage | Orifice plate diameter |
|---|---|---|
| Up to 400 m² | 3,400 L | 30 mm |
| 400.1–500 m² | 3,900 L | 35 mm |
| 500.1–750 m² | 4,600 L | 45 mm |
| 751.1–1,000 m² | 7,200 L | 50 mm |
“Active storage” excludes the volume below the orifice and above the emergency overflow, so it is not the tank’s total volume. The City verifies small-site-pathway compliance at the plumbing inspection stage. For the engineered pathway, compliance is verified at the plumbing-permit application stage. These are separate checkpoints. The figures are Vancouver’s published small-site values, not design advice or a finding that a particular lot can accommodate a tank.
Check the permit transition and sewer conditions
The City says Council approved its updated Sewer Capacity Development Review Policy on October 29, 2025. Current City materials differ on the exact transition boundary: the development-conditions resource says the updated engineered-pathway provision applies to applications opened “from January 1, 2026,” while the rainwater-management page directs permits opened “after January 1, 2026” to the 2025 Building By-law. The City’s 2026 Rainwater Management Project Summary Form is for engineered-pathway permits opened “on or after January 1, 2026.” Because these statements do not clearly resolve which bylaw version governs a permit opened exactly January 1, ask the City to confirm the applicable version in writing. For later application dates, use the current City page and operative bylaw rather than relying on an older checklist or design assumption.
The city says site-specific sewer requirements can still apply, including easements, service connections, and abandonment plans. Additional infrastructure conditions may depend on proximity to city-owned infrastructure, established boundaries, and the project’s scale or complexity. The policy transition does not confirm a property’s sewer capacity, approve a connection, or guarantee that a deeper storm connection is available.
What to verify
Confirm the site area, FSR calculation, building classification, existing-building context, application date, current bylaw version, and any site-specific rezoning or servicing conditions. Ask City Engineering and the plumbing-permit authority which pathway, drawings, calculations, and sewer reviews apply. For general distinctions among provider service, capacity, and approval, see ADU water, sewer, stormwater, and drainage checks.