Basement Flooding

This page was created as a resource to homeowners to identify possible causes of basement flooding and suggest tools and prevention methods to remedy the causes of basement flooding and improve drainage conditions at their home.  Please check out our basement flooding guide for additional information.

If you are having a sewer backup, please call the Public Works Service Centre at 519-631-0368 between the hours of 7:30 and 3:30 to arrange for a plumber to attend the scene.  If the backup happens outside of those hours, please call 519-631-1680 ext. 0 to arrange for a plumber.

If you are a resident of The City of St. Thomas, you may qualify for the basement flooding grant program.

To give us your feedback on your experience of Basement Flooding, take our Basement Flooding Survey.

There are a few different types of basement flooding:

1. Infiltration flooding - when soil around your home becomes saturated or when the ground water level rises higher than your basement and/or your weeping tiles are not working or are non-existent, water will get into your basement through cracks in the foundation walls and floor.
2. Overland flooding - when water flows overland it may enter basements through windows, doors, vents and other openings.  This could be due to improper grading, exposed window wells, and extreme wet weather conditions that exceeds the capacity of overland routes or under ground pipes.
3. Sewer backup flooding - extreme weather events can overwhelm the City's sewer system and result in flooding.  When this happens the water level in the system rises above the normal design levels.  This condition is referred to as a surcharge.  Basement flooding can cause serious damage and create a health hazard if not addressed properly.

Potential causes of flooding

A.  Weeping tiles and downspouts connected to the sanitary sewer

B.  Malfunctioning sump pump

C.  Surface Water

D.  City Sanitary sewer pipe full