The basement floor drain is usually the lowest opening in a home's drainage system. That makes it the first place water appears when the main line is blocked or when the municipal sewer is overloaded during a storm.
A basement backup can damage flooring, drywall and stored belongings quickly, so it's worth acting fast.
Common signs
- Water or sewage pooling around the floor drain
- Water appearing after laundry or showers upstairs
- Backups during or after heavy rain
- Sewage odour in the basement
What usually causes it
Main line blockage
Debris, grease or roots in the line leaving the house.
Storm overload
Intense rainfall can overwhelm sewers and push water back.
Floor drain trap issues
A dry or damaged trap can let odours and water through.
What to expect when you call
Stop using water upstairs immediately — every flush or shower adds to the backup.
Move valuables off the floor if it's safe, avoid contact with the water, and photograph damage for insurance.
In Mississauga
Basement flooding during summer storms has affected multiple Mississauga neighbourhoods. The City of Mississauga and Region of Peel provide information on reducing flood risk, including backwater valves and downspout disconnection. See our Mississauga service area for more.