Ottawa Bylaw on Disconnecting Downspouts from Storm Sewers

Unlike Toronto, which implemented a mandatory downspout disconnection bylaw in 2011, Ottawa does not currently have a citywide bylaw requiring homeowners to disconnect their downspouts from the municipal storm sewer system. However, the City of Ottawa actively encourages voluntary disconnection as part of its stormwater management strategy, and there are specific situations where disconnection may be required during property renovations or building permit applications.

Ottawa's Approach to Downspout Disconnection

Many older Ottawa homes — particularly those built before the 1970s in neighbourhoods like Centretown, Sandy Hill, the Glebe, Old Ottawa South, Vanier, and Hintonburg — have downspouts that connect directly to underground pipes feeding into the municipal storm sewer or, in some cases, the combined sewer system. During heavy rainfall, these connections contribute to combined sewer overflow (CSO) events where untreated stormwater and sewage discharge into the Ottawa River. The city's long-term Combined Sewage Storage Tunnel (CSST) project, a massive infrastructure investment, is designed to reduce these overflows, and voluntary downspout disconnection supports this goal.

The City of Ottawa's Official Plan and Infrastructure Master Plan both promote lot-level stormwater retention, which includes redirecting downspouts from storm sewers to surface drainage. While not mandatory, the city may require downspout disconnection as a condition of building permits for major renovations, additions, or new construction. If you are pulling a permit for significant work on your home, expect the building inspector to assess your downspout connections.

Disconnecting a downspout from the storm sewer is a relatively straightforward project in most cases. The underground pipe is cut or capped below grade, and the downspout is redirected to discharge at the surface with a minimum 1.8-metre extension away from the foundation, as required by the Ontario Building Code. The key consideration in Ottawa is ensuring the surface discharge has somewhere to go — with the city's clay-heavy Leda clay soil that drains poorly, simply dumping water onto the surface near your foundation can create worse problems than the storm sewer connection it replaced.

For effective disconnection in Ottawa, you need to ensure positive lot grading (ground sloping away from the foundation at a minimum 2 percent grade), adequate surface drainage routes that carry water toward the street or a permeable area, and ideally a rain garden, dry well, or rain barrel to manage the volume. Rain barrels are a popular first step — the City of Ottawa has offered rebates of $50 to $75 through its environmental programs, and a standard 200-litre rain barrel captures enough water from a single downspout to reduce storm sewer contribution while providing free garden irrigation.

The cost of professional downspout disconnection in Ottawa typically runs $200 to $500 per downspout, including cutting and capping the underground connection, adding a surface extension, and ensuring proper grading. If the underground pipe needs excavation to cap properly, costs can reach $500 to $1,000 per connection point. DIY disconnection is possible for accessible connections, but capping underground pipes requires proper materials and technique to prevent groundwater infiltration.

If you have an older Ottawa home and want to understand your downspout connections — or if you are planning eavestrough replacement and want to address drainage at the same time — a knowledgeable eavestrough contractor can evaluate your system. Browse local professionals through the Ottawa Construction Network directory at justynrookcontracting.com to find contractors experienced with both eavestrough installation and drainage management in Ottawa's unique soil conditions.