Homeowner guidePrevention
A Basement Flood Prevention Checklist
Most basement floods have warning signs or preventable causes. This checklist covers what to do outside, inside and before storm season.
A row of bathroom sinks with faucets and shadows on tiled walls, creating a serene setting.
- Short steps a homeowner can follow safely
- What to check before you pick up the phone
- Clear signs it is time to call a plumber
- Markham and York Region notes where they matter
- Licensing details confirmed when you call
- Residential
- Commercial
- Markham & York Region
The short version
- Downspouts discharge at least two metres from the foundation, onto grass, not a driveway.
- Soil slopes away from the house on all sides.
- Window wells have covers and drains.
- Eavestroughs are free of leaves.
- Catch basins on your street are clear of debris before big storms.
Inside the house
- Sump pump tested every spring and fall.
- Backup pump or battery in place if the basement is finished.
- Backwater valve on the main drain, checked yearly.
- Floor drain clear and its trap full of water.
- Water heater checked for leaks and age.
- Washer hoses braided steel, not rubber.
Before storm season
- Pour water into the sump pit to test the pump.
- Open the backwater valve cover and make sure the flap moves.
- Move valuables off the basement floor.
- Check your insurance for sewer backup and overland water coverage.
- Have a wet-dry vacuum and towels ready.
During a storm
- Limit water use if your backwater valve is closed or the sewer is surcharging.
- Glance into the pit now and then to confirm the pump is cycling.
- Do not walk through standing water near electrical outlets.
From the van: The City of Markham has offered a flood protection subsidy for devices like backwater valves and sump pumps. Rules and amounts change, so check current terms.
After a flood
- Take photos before cleaning.
- Call your insurer.
- Remove water quickly and dry the area to limit mould.
- Call a plumber to find and fix the source.