A sewer backup into the basement is unpleasant and potentially costly. Understanding why it happened is the first step to preventing a repeat.
Blockages in your private drain line
Grease, wipes, paper products and debris build up in the main line over time. Eventually the line can't carry wastewater fast enough, and it backs up through the lowest drain, usually the basement floor drain.
Tree roots and damaged pipes
Roots can enter older drain pipes through cracks and joints. Sags, offsets and cracks also catch debris. These problems tend to cause repeated backups even after the line has been cleared.
Heavy rain and the municipal system
During intense storms, municipal sewers can become overloaded. In some situations, water can back up into homes through basement drains. The City of Toronto provides information on basement flooding protection, including backwater valves, on its website.
How to tell which cause applies
If the backup happened during dry weather and was triggered by water use in your home, a private line blockage is more likely. A camera inspection can confirm the condition of your line.
Reducing your risk
- Keep grease, wipes and paper towels out of drains
- Have recurring clogs inspected rather than repeatedly cleared
- Ask a qualified professional about a backwater valve
- Keep the floor drain clear of storage and debris
If it's happening now
Stop using water, keep away from wastewater and call our sewer backup service. We're available 24/7.
Related services
- Sewer Backup Service — Urgent help when wastewater backs up into your basement or fixtures.
- Basement Floor Drain Cleaning — Clearing blocked, smelly or backing-up basement floor drains.
- Emergency Drain Service — 24/7 response for backups, overflows and urgent drain problems.
Have a drain problem now? We're available 24/7.
This article is general information, not a substitute for an on-site assessment.