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What Homeowners Can Do to Prevent Basement Flooding

Thinking homeowner
As you prepare for the cold winter months ahead, make sure your “To Do” list includes taking the necessary steps to prevent basement flooding. Hundreds of thousands of dollars are lost each year from basement flooding. Regardless of the use – for storage, a work area, a laundry room, a play area or extra living space – water damage or loss of personal property from flooding can be upsetting and expensive. Your furnace, water heater and electrical system can be compromised with just a few inches of water and risk your family’s safety. In addition, long-term respiratory and other health issues can occur from mold, mildew and bacteria growth after exposure to a damp basement. Severe weather can occur with little notice and so can water infiltration. Often, homeowners just don’t have time to move expensive appliances, furniture, tools or prized possessions to higher ground. Even worse, a flooded basement can weaken the structure of the home and damage flooring, wallboard and the foundation. Envisioning this type of potentially disastrous event can be overwhelming, but with a little planning, you can control and even prevent basement flooding.


Internal – flooding caused by blockage, equipment failure or homeowner mistake.

  • Use special burst-proof piping for the washing machine.
  • Add a lint collector on washing machine drain to prevent sink back-up.
  • Keep laundry sink drain clear from obstruction.
  • Check dishwasher for loose or cracked connections.
  • Make sure the sump pump is sized appropriately and operating properly.
  • Install battery or hydro-powered back-up to sump pump.
  • Backwater valve should be checked for proper operation.
  • Don’t pour grease or fats down drains.
  • Repair cracks in foundation and floor.
  • Purchase a back-up generator to keep sump pump operating if power goes out.
  • Activate monitored flood and heat sensors through security system.
  • Schedule an inspection by a licensed plumber to identify other problem areas.

External – water infiltration and overland flooding.

  • Remove leaves and debris from gutters and downspouts to prevent overflow.
  • Re-direct downspouts so water flows away from the foundation.
  • Seal basement windows with caulking and weather stripping or add storm windows.
  • Clean out window wells and drains by removing debris; add covers to block water infiltration.
  • Keep storm sewer grates clear.
  • Grade soil away from the foundation.
  • Install drain tiles along foundation perimeter.
  • Turn off outside faucets to avoid freezing or rupturing.
  • Protect sump pump discharge pipe from freezing with insulation.
  • Maintain sewer laterals for clear drainage.
  • Clear storm sewer grates of obstruction.
  • Schedule an exterior home inspection by a waterproofing company.

If preventative measures fail to protect your basement from flooding, there may be some additional things you can do to help reduce your risk of loss:

  • Prevent overland flood waters from entering your basement by sealing all gaps and openings. Typical problem areas are window and door framing, mortar cracks, plus wire and cable openings. Use caulk and weather stripping to close these gaps.
  • Store items off the floor and leave the basement unfinished.
  • Reduce water usage during severe rainstorms so less water drains into storm and sanitary sewers.
  • Purchase separate flood insurance to cover any gaps in homeowners’ policy.


Overland flooding may be a recurring problem in some communities. Homeowner’s can discuss problems with their municipal government representatives. Plans may be in place for improvements or remediation, flood potential information packets may be available, plus recommended contractor listings or financial assistance programs may provide additional flood coverage.

The City of Toronto Basement Flooding Protection Subsidy Program provides up to $3,400 in subsidy dollars to homeowners for installation of flood protection devices. Single-family, duplex and triplex residences are eligible to receive reimbursement for the installation of a sump pump or backwater valve by a licensed City of Toronto plumbing contractor. Disconnecting from the City’s sewer system through pipe severance and capping are also eligible projects.

With a plan in place to reduce the potential for basement flooding, you can now enjoy the winter season knowing you and your family are well protected.

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