Reduce your Risk of Basement Flooding

Every home is at risk of basement flooding, even if there has never been a flooding incident. Water in your basement is most likely to occur when there’s been a heavy rainfall, snow is melting or we’re experiencing a spring thaw. The good news is that you can prevent or at least reduce the chance of this happening.


Causes of basement flooding on private property:

There are a number of reasons why basements flood. Flooding can occur:

  • When storm water or ground water seeps into the home (drainage failure):
      • A crack or leak in your home’s foundation, basement walls, or basement windows or door.
      • Poor lot grading or drainage
      • Failure of the weeping tile system (foundation drains)
      • Failure of a sump pump (in some homes) used to pump weeping tile water.
      • Overflowing eaves troughs
      • Leaking or plugged downspouts
  • From a sewer backup:
      • When waste water from the sanitary system or a combination of waste water and storm water from the combined sewer system back up into the property, usually through fixtures tied to the sanitary sewer lateral, including the floor drain, toilets, sinks, showers and laundry fixtures located in the basement.
      • A sewer backup can result from a blocked connection between your home and the main sewer in the street, a sewer main backup or when the sewer system becomes overwhelmed with storm water.

Understanding sewer system

There are three types of sewers:

  • Sanitary sewer: The sanitary sewer, which carries waste water (sewage), is connected to a home’s plumbing (toilets, sinks, laundry, floor drain etc.) and leads to a waste water treatment
  • Storm sewer: The storm sewer collects storm water from catch basins (street drains), connected downspouts, weeping tiles (in many areas of the city) and carries these flows into nearby watercourses.
  • Combined sewer: In older parts of the city, storm water and sewage are collected in the same pipe known as a combined sewer. During normal weather conditions, all the waste water in the combined sewer is treated at the waste water treatment plant.

What Cities are doing to stop flooding

Take flooding incidents seriously these steps to stop the overloading of the sewer system and reduce basement flooding.

  • Mandatory Downspout Disconnection Program requires homeowners to disconnect their home’s downspout from the City’s sewer system, where feasible, to help reduce sewer flows.
  • Basement Flooding Protection Subsidy Program provides up to $3,400 to owners of single-family, duplex and triplex residential properties to install flood protection devices, including a backwater valve, a sump pump, and disconnecting external weeping tiles from the sewer system (by severing and capping connected pipes.)
  • Regular inspection, cleaning and maintenance of the City’s sewer system.

Stop the flood before it starts

Here are some steps you can take to reduce the likelihood of basement flooding.

What you can do outside the house

  • Seal cracks or openings in walls, floors, windows and foundations, and seal all window wells.
  • Clear eaves troughs and downspouts of leaves and other debris that prevent proper drainage.
  • Disconnect your downspouts from the sewer system, where feasible (without negatively affecting neighboring properties or creating an area where water will pool on a sidewalk or driveway) .
  • Make sure your disconnected downspouts are draining properly, ideally (six and a half feet) from your foundation’s walls.
  • Ensure the grading around your home slopes away from the foundation wall to help drain water away from your home (without negatively affecting neighboring properties).
  • Increase the green space around your home with native plants and shrubs and install porous pavement to help absorb rainwater and melted snow.
  • Repair/replace damaged weeping tile systems.
  • Clear debris from roadside catch basins (grates) to help water enter the storm sewer. (If it is safe to do so.)
  • Ensure drainage swales (shallow ditch) between properties are maintained and clear of obstructions.

What you can do inside the house

  • Ensure that your plumbing and drainage systems are in good working condition. Homeowners are responsible for the plumbing from the property line to inside the home.
  • Part of reducing the risk of basement floods is to understand how your plumbing and foundation drainage systems work and how to maintain them. Every home is different and homes over time have been built with different building practices and building codes. Some of what you should know about your home, includes:
    • Know the location and condition of your sewer lateral (the pipe that connects the plumbing in your home to the main line on the street).
    • Find out if you have a storm sewer lateral (pipe) and if so the location and condition of it.
    • Find out if you have a backwater valve or sump pump, and if so, how to maintain them. Understand what is needed to keep a sump pump operational during power outages.
    • Find out if you have weeping tiles and if so, their condition and where they are connected. (A weeping tile is a perforated pipe that runs around the perimeter of your foundation to intercept groundwater. The weeping tile gives the groundwater a place to go. Where it goes depends on the type of foundation drainage system your home has.)

To understand some of these elements of your home, you may want to hire a licensed plumber who can conduct specialized testing or inspection, often through video camera inspection.

  • Once you understand your plumbing and drainage systems, you also have to maintain them.
    • Fix cracks, blockages or other condition problems.
    • Avoiding creating clogs:
      • Toilets are not for trash. Do not flush down the toilet items such as dental floss, personal care products (including “flushable” wipes), condoms, tampons, razor blades or anything which can block the sanitary pipe.
      • Never pour any fats, oils, and grease down the drain.
  • Hire a City-licensed and qualified plumber to install a backwater valve and a properly-sized sump pump and piping. Ensure the proper and regular maintenance of basement flooding devices in your home.Sump pumps need power to operate, so consider installing a back-up power source.
  • Seal cracks or openings in walls, floors, windows and foundations, and seal all window wells.

Information on backwater valves and sump pumps

Consider hiring a city-licensed plumbing contractor to conduct a detailed plumbing investigation to help assess and recommend options to reduce flooding. It is advisable to get estimates before going ahead with any work. Your city may offer a financial subsidy of up to $3,400 to homeowners of single-family, duplex or tripleplex residential homes to install flood protection devices through the Basement Flooding Protection Subsidy Program.

A licensed plumbing contractor can assist to:

  • Install a backwater valve on your sanitary and/or storm sewer line to prevent water from backing up into your basement. Backwater valves need to be installed properly and regularly inspected and maintained. Find out which type of backwater valves the city’s subsidy program will cover.
  • Install a properly-sized sump pump to help pump out water collected by the weeping tile system to an area outside. Make sure the sump pump empties onto a permeable surface at least 2 meters from the foundation wall. Sump pumps can lose power during severe storms, so you may wish to consider a battery back-up.
  • Backwater valves and sump pumps need to be inspected and maintained to ensure optimal performance.
  • Some work may need a building permit. For information on how to obtain permits, call 311.

What to do when your basement has flooded

  1. If you experience basement flooding, contact 311 immediately (24 hours a day, seven days a week). city staff will inspect the problem, assess the flooding and attempt to determine the source(s) of the flooding.
    1. Don’t use toilets and sinks unless it is absolutely necessary until the issue has been resolved. (Any water sent down the drain may end up in your basement.)
  2. Call your insurance company as soon as possible and report property damage caused by the flooding:
    • Take photos of damage caused by flooding for your insurance claim.
    • Keep receipts from emergency repair work or clean-ups done to prevent or reduce further damage.
    • If the flooding is a result of a blocked drain pipe, leaking foundation walls or poor lot drainage on your property, then you are responsible for repairs and any subsequent damage caused by flooding. Contact your insurance company to discuss coverage.
  3. Be mindful of health and safety when cleaning up your flooded basement. Exposure to contaminants carried by flood water or sewer back-ups into basements can be dangerous. Homeowners may be exposed to waterborne diseases, corrosive cleaning agents and irritants found in leftover sludge from a flooded basement. Electrical accidents may occur because of contact with water and electricity.

Keep your plumbing clear

Avoid creating blockages in your plumbing and the city’s sanitary sewers:

  • Dispose of small amounts of cooking oil and grease in your green bin (making sure there’s material to absorb it). Never pour oil or grease down the kitchen sink or into the toilet. Grease can build up and cause blockages in the city’s sanitary sewer pipes, which can cause basement flooding.
  • Toilets are not for food, trash, dental floss, Q-tips, or other personal care objects, including “flushable wipes”. These should be disposed of in the appropriate bin.


Get the Facts on Basement Flooding

Basement flooding can occur any time. It can happen to anyone who has a basement, even if it has never flooded before. While most flooding occurs during big rains or rapid snow melts, it can happen even during dry weather.

Everyone in a community plays a role in helping to prevent basement flooding. If we all take preventative measures, we can make a significant impact in reducing flooding throughout a city.

Flood Facts and Tips:

  1. All basements are at risk.If you have a basement, you’re at risk of basement flooding, even if it’s never flooded before.
    We suggest that you do not store any valuable property in your basement, but if you do, take measures to protect them from flooding.
  2. Your actions affect your entire neighborhood.
    Changes to a home’s plumbing or lot drainage can help reduce the chance of flooding whether its your own home or your neighbors.
    It takes the entire community working together to make a positive impact on flooding. One person may be “just a drop in the bucket”, but collectively we can make a big difference.
  3. Have a plumber inspect your sewer lateral every 5–10 years.
    Having your lateral inspected can help you find and fix problems before a flood happens.
    The sewer lateral is the pipe that connects your homes internal plumbing to the sewer main in the street. It is a vital component of the system, and if it is blocked, or fails, your home will experience a sewage backup.
  4. Dispose of cooking fats, oils, and greases in your Green Bin, not your drain.Never dispose of fats, oils, or greases down the drain or toilet.
    Let hot cooking fat cool in a clean and dry juice carton whose top has been cut off. When it has solidified, transfer it Green Bin.
    Replace the tin can shown at left with a clean juice carton.
    Tin cans cannot go in the Green Bin.
  5. Know your insurance coverage.
    Speak directly to your insurer to find out if your policy protects you against sewage backups and water damage.
  6. Understand how your drainage and plumbing works.
    Learn what danger signs to look for and how to maintain your home’s drainage and plumbing. Talk to your plumber or your home inspector, and watch for additional information appearing here in the next few weeks.
  7. Sump pumps can keep your basement dry.Installing or upgrading your sump pump may help prevent basement flooding in your home. Also, consider providing a backup power source for your sump pump.
  8. If you have a sump pump, make sure that it drains only onto your lawn or into the storm sewer.
    Sump pumps that connect directly to the sanitary sewer are illegal. This sort of a connection puts you and your neighbor’s properties at risk.
  9. Reduce your water use on rainy days.
    When it’s raining heavily the sewers may fill up. Using a lot of water during heavy rains (for example, taking a shower or doing laundry) can contribute to basement flooding and overflows to your environment. Consider using less water in extreme weather situations.
  10. Check all of your downspouts.Properly connected downspouts reduce flooding in your neighborhood.
    In most cases, the downspout should be draining over top of the lawn, at least 2 meters away from your house.
  11. Manage your property’s run-off.
    There are many natural ways to manage run-off on your property, including rain barrels, conservation gardens, proper sloping, and so on.
  12. Lot grading can help move water away from your home.
    The chance of a basement flood increases when more groundwater sits around your foundation. Keeping the ground surface sloped away from your home is one way to reduce the water around the foundation. Consider redoing the landscaping around your house as it may settle over time.
  13. Inspect your property when it rains.
    Walk around your property when it rains to find the places where water may be getting into your home or where pooling water needs to be managed.
  14. Maintain your home’s foundation.
    One common way for water to get into your basement is through cracks that may form as your home ages and settles. Maintain your foundation by sealing any cracks that may have formed and consider waterproofing the exterior walls.
  15. Keep your eaves troughs and downspouts clear of debris.
    Eaves troughs and downspouts that are clear of leaves and other debris are an essential part of helping rain water run safely away from your home and off of your property.
  16. Install a backwater sanitary valve.
    Installing and maintaining a backwater sanitary valve can help prevent basement flooding in your home.
  17. Clear clogged catch basins.
    Keeping catch basins clear of debris will help prevent local flooding. If you see one that’s blocked with leaves or debris, we’d appreciate it if you could take a few moments to remove the blockage.
  18. Know the“The Sewer By-law”.
    By-law 2008-192 is intended to help protect properties from flooding. Understanding and following the by-law is everyone’s responsibility.

Notify Your City Whenever You Have a Flood

Knowing where basement floods are happening helps us plan investigations and potential improvements to the City’s infrastructure. We’re also interested in hearing about historical flooding.

How You Can Prevent Sewer Line Backups

There are several preventive measures homeowners can take to minimize the occurrence sewer line backups.

  • Proper Disposal of Grease and Food: Grease, fats, gravies, sauces and cooking oils should never go down your kitchen drain but should be poured into a heat-resistant container and disposed of in the garbage. Once in your drain, these substances will cool off and solidify either in the drain or in the main sewer, eventually building up to a massive clog. Food particles should never go down the drain unless run through a garbage disposal first.
  • Proper Disposal of Paper Products Properly: Toilet paper and human waste is the only thing that should go down your toilet. Diapers, paper towels, feminine products and food should never be flushed; these products do not deteriorate and can easily clog your main sewer line. Even facial tissue should be avoided; it does not dissolve as easily as bathroom tissue does.
  • Replace Your Pipes: One way to prevent collapsed sewer lines or tree root infiltration is to replace your old clay or metal sewer lines with today’s newer plastic or PVC pipe. If you have continuing problems with tree roots in your sewer line, you may have to have the roots cut or your line cleared periodically.
  • Install a Backwater Prevention Valve: These fixtures are installed into a sewer line in the basement of your home to prevent sewer backups. They allow sewage to go out, but not to come back in.

What to Do If You Experience a Sewer Backup

Sewer backups can produce a host of nightmares for homeowners, including disease, mold formation, destruction of valuables, foundation damage and electrical malfunctions. Prompt cleanup is necessary to restore sanitary conditions and prevent further damage. If you experience a sewer backup situation, at a minimum, your cleanup should include:

  • Wet-vacuuming of all floodwater
  • Mopping floors and wiping walls with soap, water and disinfectant
  • Flushing and disinfecting plumbing fixtures
  • Steam cleaning or removing wet carpets or drapes
  • Repairing/removing damaged wall and floor covering
  • Cleanup of ductwork

Important things you can do to reduce basement flooding and its risks:

  • Never dump anything into street sewers. Leaves, grass clippings, motor oil and other items keep sewers from flowing and pose a hazard to people working in the sewers.
  • Make sure that the catch basins on your street are not covered by trash, leaves, paper, or other items. Blocked catch basins can cause street flooding.
  • Clean your private drain system regularly. Also have them inspected annually.
  • Disconnect sump pumps/downspouts from sanitary sewers.

Sewer Terminology

sewageVery few people understand the terminology associated with the sewer system. This sidebar gives you a quick guide to sewer vocabulary that will help you understand sewer back-ups.

Sanitary Sewer – the pipes that handle waste water from toilets, sinks, showers, etc. this waste eventually ends up at a waste water treatment plant where it is cleaned before being discharged into the environment.

Storm Sewer – the pipes that handle stormwater (usually from catch basins in the street) which run to streams, ponds, rivers, lakes, etc. without being cleaned.

Combined Sewer – in older cities storm and sanitary sewers are “combined” and all the water is cleaned at a wastewater treatment facility. Because stormwater can overload the sewers, this is not the best way to treat wastewater. It would, however, cost taxpayers billions of dollars to dig up city sewers and separate them.

Main Sewer – the sewer pipe in the street, generally a municipal responsibility.

Building Lateral – the pipe that carries sewage to the main sewer in the street. This entire pipe (along with all the plumbing within the building) is the responsibility of the building owner.

Lot Line Cleanout (LLCO) – some properties have an access pipe installed down to the building lateral (generally located on the property side of the sidewalk) that allows the municipality to maintain/repair the building lateral out to the main sewer (the actual LLCO pipe—and locating it for municipal service—is the building owner’s responsibility).