Resource
Common Causes of Basement Flooding
Where lower-level water actually comes from, and what each source tends to look like.
Water from below
Groundwater pressure pushes moisture through the cove joint where the floor slab meets the foundation wall, and through cracks in block or poured concrete. This kind of entry is usually gradual and follows rainfall.
Water from outside at grade
Window wells without drainage, downspouts discharging beside the foundation and grading that slopes toward the house all concentrate water where it is least wanted.
Mechanical failures
Sump pumps fail through worn floats, seized motors, blocked discharge lines and power interruptions during exactly the storms that need them working.
Water from inside
Water heaters, laundry connections and basement bathroom fixtures release water directly onto the slab, often unnoticed in a rarely used area.
Drainage backups
When municipal lines surcharge in heavy rain, water can push back through floor drains. A functioning backwater valve is the main defence against this path.
This guide is general information for Scarborough property owners and occupants. Conditions at your property should be assessed individually.