Rainwater management on private property

Note All new rezoning developments continue to require rainwater management. Starting July 25, 2023, you will no longer need to submit rainwater management plans with your rezoning application. 

At the building permit application stage, you’ll need to show compliance with:

• The Vancouver Building By-law rainwater management requirements (in effect on January 1, 2024)
• Any site-specific rainwater management conditions approved by Council

Review the amendments to the Building By-law PDF file (157 KB)

Note For all new development permit applications [excluding rezoned sites and those in the First Shaughnessy district PDF file (202 KB)], rainwater management requirements will depend on when a new development permit application is approved for intake.

Until December 31, 2023

We will continue to assess new development permit applications to determine if rainwater management is required. This is usually the case for new developments located:

• In a rainwater management area of concern
• Where adequate drainage is unavailable

If rainwater management is:

• Required - You no longer need to submit rainwater management plans. Instead, at the building permit application stage, you’ll need to show compliance with the rainwater management requirements of the Vancouver Building By-law that will be in effect on January 1, 2024. Review the amendments to the Building By-law PDF file (157 KB)
• Not required - You will be sheltered from the new Vancouver Building By-law rainwater management requirements that will be in effect on January 1, 2024.

Effective January 1, 2024

All new development permit applications for Part 3 buildings in Vancouver (excluding residential buildings with up to 8 dwelling units) must demonstrate compliance with the rainwater management requirements of the Vancouver Building By-law that will be in effect. Review the amendments to the Building By-law PDF file (157 KB)

Note “In-stream” rezoning applications will continue to be processed using the Rainwater Management Bulletin PDF file (903 KB) until December 31, 2023. It is no longer available after that date.

Effective January 1, 2024

To make sure your application is processed quickly, we will examine all “in-stream” rezoning applications that have not yet been issued a development permit.

The new Vancouver Building By-law rainwater management requirements may help expedite your development permit approval.

For development permit applications approved for intake before January 1, 2024

If rainwater management is:

• Required - You may continue to follow the rainwater management plan process described in the Rainwater Management Bulletin PDF file (903 KB) until December 31, 2023. It is no longer available after that date.
• Not required: You will be sheltered from the new Vancouver Building By-law rainwater management requirements that come into effect on January 1, 2024.

Effective January 1, 2024

To help you receive your development permit faster, we will examine all “in-stream” development permit applications that have not yet been issued a development permit.

The new Vancouver Building By-law rainwater management requirements may help expedite your development permit approval.

• Zoning and Development By-law (Section 4.3) PDF file (158 KB) in effect until December 31, 2023
• Building By-law rainwater management requirements PDF file (157 KB) in effect January 1, 2024
• Sewer and Watercourse By-law PDF file (346 KB)
• Engineering Design Manual (Section 5) PDF file (10 MB)
• City Council Referral Report (June 13, 2023) PDF file (696 KB)

In a combined sewer system, rainwater runoff is combined in a single pipe with wastewater from homes, businesses, and industry. During drier weather, the rainwater and wastewater are both carried to the sewage treatment plant. In heavy rains, however, high volumes of rainwater can exceed the capacity of a combined sewer system. The excess, untreated mix of rainwater and sanitary sewage overflows and empties directly into our waterways, which may also be habitat for aquatic species.

Contaminants are introduced into rainwater from a variety of sources, including air deposition, wearing of building and infrastructure materials, motor vehicles, litter, and fertilizers. Untreated rainwater runoff carries these to nearby waterbodies, reducing water quality, impacting aquatic life and public uses. 

By 2050, Vancouver is expecting a 5% increase in the volume of winter rain with slightly larger increases in spring and fall. It is also anticipated that Vancouver will see a 19% decrease in rain during the summer. Further, extreme rainfall events are projected to increase in frequency and intensify overall with 63% more rain on extremely wet days. These factors could lead to increased surface flooding, sewer back-ups, and combined sewer overflows.

A pervious surface allows water to penetrate through to the ground underneath rather than becoming runoff. As Vancouver developed over its history, the city has experienced a general loss of pervious surfaces and an increase in impervious surfaces that prevent water infiltration. Several consequential side effects result from this, including greater likelihood of surface flooding, increased contamination of local waterbodies, and reduced recharge to groundwater resources.

Flooding may occur due to unintended rainwater entering buildings, exceeded sewer system capacity, developments being built on a floodplain, construction dewatering, or other causes related to rainwater. Also, climate change is expected to cause higher intensity rainfall exacerbated by rising sea levels, increased intensity and duration of storms, or both. As such, flooding is of particular concern during wet seasons.

Vancouver’s population is expected to grow over the coming decades. Each new resident will use water that goes into sewers for treatment. Properties are also densifying to accommodate this influx of residents, which has resulted in more impermeable surfaces that channel storm water directly into sewers. These factors combine to place additional strain on the existing sewer capacity.

The core of the existing sewer system in Vancouver was designed in the early-mid 20th century. The deployment of water-efficient fixtures and appliances, and green rainwater infrastructure, extends the limited capacity of the existing sewer and drainage infrastructure.