Know which kind you had
| Clue | Likely source |
|---|---|
| Water at the floor-wall joint, clear | Groundwater, grading, downspouts |
| Water up through the floor drain, smelly | Sewer backup |
| Damp patch on one wall after rain | Downspout or grading on that side |
| Water from the ceiling | Plumbing leak or ice dam, not a flood |
Outside the house
- Soil should slope away from the foundation for the first couple of metres.
- Downspouts should discharge well away from the walls onto your own property.
- Window wells need clear drains and ideally covers.
- Driveways that slope toward a garage or basement door need a working trench drain.
Areas near the West Don and East Don ravines, low-lying streets, and older neighbourhoods with combined or overloaded sewers have seen flooding in big storms.
From the counter
Inside the house
- Backwater valve on the main sewer line stops city sewage from flowing back in.
- Sump pump removes groundwater collected by the weeping tile.
- Battery backup keeps the pump going when a storm takes out power.
- Floor drain trap kept full so it seals properly.
North York risk factors
Areas near the West Don and East Don ravines, low-lying streets, and older neighbourhoods with combined or overloaded sewers have seen flooding in big storms. A house on a low street that took water in a past storm should treat a backwater valve as standard equipment.
Habits during a storm
When a heavy storm is forecast, hold the laundry and the dishwasher. If you have a backwater valve, the less water you send down during a surge, the better. Check the sump pump is plugged in and the pit is clear.
Questions
Will a backwater valve alone keep me dry?
It stops sewage backing up from the city side. It does nothing for groundwater coming through walls, which is the sump pump and grading job.
Can I just cap the floor drain?
No. The floor drain is needed for water heater and laundry spills. Protect it with a backwater valve instead.