Basement Flood Prevention

Although you may have been lucky to never have your basement flood, every home is at risk of basement flooding. Heavy rainfall and melting snow during the spring thaw out season increases the chance of water seeping into your Toronto home basement which can lead to mild to sever flooding that can costs you thousands to repair. Rooter-man has solutions available to prevent or at least reduce the chance of this happening to you and your home.

Causes of Basement Flooding on Private Property:

Flooding can occur:

  •  When water from the storm or ground water seeps into the foundation of 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)
    • The failure of a sump pump (in some homes) used to pump weeping tile water out of the home.
    • Overflowing eavestroughs
    • Leaking or plugged downspouts
  • From a clogged sewer or sewer backup:
    • When the stormwater or waste water from the sanitary system or a combination of the two back up into the property through fixtures tied to the sanitary sewer lateral that include the toilets, floor drain, sinks, showers and laundry fixtures that are located in the basement
    • A blocked connection between your home and the main sewer in the street can result in a sewer backup where the sewer main backup or sewer system become overwhelmed with stormwater and cannot keep up with the influx of heavy volumes.

Understanding Toronto’s sewer system

There are three types of sewer systems in Toronto:

  • Sanitary Sewer System: This system is connected to a home’s plumbing (toilets, sinks, laundry, floor drain etc.) and carries wastewater (sewage) from the home to the wastewater treatment plant.
  • Combined Sewer System: In oder parts of Toronto, stormwater and sewage are collected in a combined sewer (in the same pipe). Even throughout normal weather conditions, all wastewater in the combined sewer is treated at the wastewater treatment plant
  • Storm Sewer System: This type of system collects stormwater from catchbasins (street drains), connected downspouts, weeping tiles (throughout many areas of the city) and carries these flows into nearby watercourses that ultimately lead into Lake Ontario.


The City’s Provisions to Prevent Flooding

It is paramount to take flooding incidents seriously, especially developed urban areas where buildings are closer together making them more susceptible to major flooding incidents. Rural areas also have their challenges. The City of Toronto has taken the steps to stop the overloading of the sewer system by:


  • Creating a Mandatory Downspout Disconnection Program that requires homeowners to disconnect their home’s downspout from the Toronto’s sewer system, where feasible, to help minimize sewer flows. (City of Toronto Municipal Code, Chapter 681, Sewers)
  • Developing the Basement Flooding Protection Subsidy Program that provides up to $3,400 to single-family, duplex and triplex residential property owners to install flood protection devices that include a backwater valve, a sump pump, and disconnecting external weeping tiles from the sewer system (by severing and capping connected pipes.)
  • Work is underway across Toronto to make improvements to local sewer systems and overland drainage. Read more about the Basement Flooding Protection Program.
  • Regular inspection, cleaning and maintenance of the City’s sewer system.


How to Stop the Flood Before it Begins

See below for steps your can take in order to reduce the likelihood of basement flooding.

Steps to Take Outside the House

  • Be sure to seal any and all cracks or openings in walls, floors, windows and foundations, and seal all window wells.
  • Ensure eavestroughs are clear of downspouts of leaves and other debris that prevent flow and proper drainage.
  • Disconnect, where feasible (without negatively affecting neighbouring properties or creating an area where water will pool on a driveway or sidewalk), your downspouts from the sewer system.
  • For ideal drainage, ensure your disconnected downspouts are draining properly from your foundation’s walls, ideally two meters (six and a half feet)
  • Without negatively affecting the neighbouring properties, ensure the grading surrounding your home slopes away from the foundation wall to assist in helping drain any water away from your home.
  • Try to increase the green space surrounding your home with native plants and shrubs; also install porous pavement to help absorb rainwater and melted snow.
  • Make sure to replace or repair damaged weeping stile systems
  • Safely ensure roadside catchbasins (grates) are clear of debris to help water enter the stormsewer
  • Drainage swales (shallow ditch) between properties should be clear of any obstruction

Steps to take Inside the House

  • It’s recommended to inspect the plumbing on your property yearly as homeowners are responsible for the plumping from the property line to inside the home
  • Understanding how your plumbing and foundation drainage systems work and how to maintain them can partly help to reduce the risk of basement floods.
  • Every home is different and over times, homes have been built with different building codes and practices.
  • Be sure to know:
    • 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 better understand these elements of your home, hire a licensed plumber who can conduct specialized testing or inspections of the property, often through invasive video camera inspection.
  • Understanding your plumbing and drainage systems will help with maintenance
  • Ensure to fix cracks, blockages or other condition problems as soon as they appear.
    • Avoid creating clogs:
      • Toilets are not an alternative to the disposal of trash. Do not flush down the toilet items such as dental floss, personal care products (including “flushable” wipes), condoms, tampons, razor blades or anything that can block the sanitary pipe.
      • Do not pour any fats, oils, or grease down the drain.
  • When installing a backwater valve and a properly-sized sump pump and piping, be sure to hire a qualified City-licensed plumber. Sump pumps need power to operate, so consider installing a back-up power source to offset any poweroutages that may occur.
  • Regular maintenance of basement flooding devices in your home is essential

Click picture for larger image

basement Flood Waterproofing



 Information on backwater valves and sump pumps

In order to reduce flooding, we recommend hiring a City-licensed plumbing contractor (i.e Rooter-Man) to conduct a detailed plumbing investigation in order to assess and provide recommendations and options available for all plumbing needs. Once the plumbing investigation has finished be sure to get an estimate so you may budget accordingly before any work begins.

Cities of Toronto, Mississauga or Oakville offers up to $3,400 financial subsidy to homeowners of single-family, duplex or tripleplex residential homes to install flood protections devices to take advantage of the Basement Flooding Protection Subsidy Program. For more details, go to : Basement Flooding.

A City licensed plumbing contractor can:

  • Install  backwater valves (see diagram below) on your sanitary and/or storm sewer line in order to prevent water from backing up into your commercial or home’s basement. It is important that backwater valves be installed properly and regularly inspected and maintained for maximum performance. To find out which type of backwater valves the City’s subsidy program will cover go to: Basement Flooding.
    Install a backwater valve diagram
    Important: Backwater valves are designed to close the sewer line and prevent any water from entering into your home. Do not use any plumbing fixtures such as toilets, dishwashers, sinks, washing machines, etc., as it will prevent water from draining through the sanitary line and will result in it backing up into your home.


  • Install properly-sized sump pump, (see diagram below) to pump out water collected by the weeping tile system to an area designated outside. Be sure the sump pump empties onto a permeable surface no less than 2 meters from the foundation wall. A battery back-up is recommended as sump pmps can loose power during sever storms.
    Install a properly-sized sump pump diagram
  • Backwater valves and sump pumps need to be regularly inspected and maintained to ensure optimal performance.
  • Some plumbing projects may need a building permit. For information on obtaining permits, call 311 or visit Toronto Building

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If your  Basement has Flooded you Should:

  1. Contact 311 immediately (they operate 24 hours a day, seven days a week) or visit enter a self-service request. City staff will arrive to inspect the problem, assess the flooding and attempt to determine the source(s) of the flooding.
    • Prevent the use toilets and sinks unless it’s absolutely necessary until the matter 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 any property damage caused by the flooding:
    • Ensure to document the damage and take photos of what caused the flood for your insurance claim.
    • Be sure to keep receipts from any emergency repair work or clean-ups done to prevent or reduce further damages.
    • You are responsible for repairs and any subsequent damage caused by flooding if the flooding is a result of a blocked drain pipe, leaking foundation walls or poor lot drainage on your property. Contact your insurance company to discuss coverage.
    •  Submit a claim in writing with your name, telephone number, home address, date, location and all relevant details of the incident and send it to:
      City Clerk’s Office, City of Toronto
      City Hall, 100 Queen St. W.
      Toronto, ON  M5H 2N2
      Or fax: 416-392-2980 or e-mail

    Your claim will be sent to the City’s insurance adjustors for evaluation and a letter of acknowledgement will be sent to you.

  3. It is important to be mindful of health and safety codes when cleaning up your flooded basement. Exposure to harmful contaminants carried by flood water or sewer back-ups into basements can be dangerous. Homeowners could possibly be exposed to all kinds of waterborne diseases, corrosive cleaning agents and irritants found in leftover sludge from flooded basements. Electrical accidents may also occur because of contact with water and electricity.
    • We suggest to hire a professional cleaning company familiar with cleaning sewage contaminated basements.
    • Ensure children and pets are kept out o the affected area until clean up has been completed
    • Dressing appropriately is paramount for your own safety– wear overalls, gloves, protective eyeglasses, rubber boots and a mask.
    • Open windows to let fresh air in for better respiration.
    • Steer clear from electrical equipment. If uncertain of potential electrical hazards have a qualified electrician assess the situation.
    • If possible shut off the electrical power. (Note: would affect the operation of a sump pump or sewage ejector).
    • If you detect gas, leave the house immediately and contact the gas company. Water could extinguish a pilot light on a gas appliance.
    • In regards to the disposal of minor debris, it can be put out for regular garbage pick-up (See your Garbage and Recycling Collection Calendar for information).
    • Throw out all contaminated items that cannot be washed and disinfected(mattresses, carpeting, carpet padding, rugs, upholstered furniture, cosmetics, plush toys, baby toys, pillows, foam-rubber items, books, wall coverings, and most paper products).
    • Thoroughly wash all surfaces with hot water and liquid detergent, rinse and dry and ventilate the area using a  de-humidifier and fans if necessary.
    • Sanitizing the walls and floors using a solution of household bleach (mix 1 cup bleach with 5 gallons of water) is highly recommended to disinfect any remaining bacteria. For more details, visit the Centre for Disease Control and Prevention’s website.
    • Remove and discard all drywall and insulation that has been contaminated with sewage or flood waters, these cannot be cleaned.
    • Wash all clothes worn during the cleanup in hot water (check manufacturer’s washing instructions) and detergent for best results. They should also be washed separately from uncontaminated clothes and linens.
    • Discard canned foods, home-prepared foods that are in jars, meats and dairy products and any packaged foods that may have been affected by the flood and sewage waters – check for any damaged packaging, leaks, and corrosion at seams and joints of cans and throw them out.
    • Move frozen food to another freezer or throw it out if you can’t keep it frozen if you have lost power
    • When in doubt, throw it out. It is not safe to consume potentially contaminated food. For more information visit Toronto Public Health for information on food safety after a power outage.
    • Visit Toronto Public Health for more information on cleaning up after a flood.


Keeping your Plumbing Clear

You can avoid creating blockages in your plumbing and the City’s sanitary sewers by:

  • Disposing 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 as it can cause grease to build up and create blockages in the City’s sanitary sewer pipes that can lead to basement flooding.
  • Toilets are not meant for the disposal of food, trash, dental floss, Q-tips, or any other personal care objects, including “flushable wipes”. These should be disposed of in the appropriate bin.
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