Guide: roof water
Downspout Disconnection and Your Basement
Downspouts connected to the sewer can overload it during storms. Disconnecting them is simple and helps protect basements.
- Cut the downspout about 25 centimetres above the standpipe.
- Cap the standpipe securely so nothing can enter.
- Attach an elbow to the downspout.
- Add an extension to carry water at least 2 metres from the foundation.
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Why disconnect
Many older Toronto homes have downspouts piped directly into the sewer through an underground connection. During heavy rain, all that roof water adds to sewer flow and can contribute to basement backups. Toronto has a bylaw requiring downspout disconnection in most cases. Check current city rules for exemptions and details.
How to disconnect
- Cut the downspout about 25 centimetres above the standpipe.
- Cap the standpipe securely so nothing can enter.
- Attach an elbow to the downspout.
- Add an extension to carry water at least 2 metres from the foundation.
- Add a splash pad to stop erosion.
Check the grading
Water from downspouts must drain away from the house. If the ground slopes toward the foundation, add soil to create a gentle slope. Clear gutters each fall to prevent overflow.
Related protection
Downspout disconnection works best with a backwater valve and a sump pump. See basement flooding protection for an overview.
Questions we get about this
What if my lot is too small for an extension?
Some properties qualify for an exemption, or need a different approach such as a rain barrel or a splash pad aimed along the wall. Check the city’s current rules.
Will disconnecting cause ice on my driveway?
It can if the extension points the wrong way. Aim water toward lawn or garden beds and away from paths, steps and the street.