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Protect your home from basement flooding

It's important to protect your home from basement flooding because no matter where you live in Winnipeg, your home is at risk of basement flooding. Why?

  • Heavy rainstorms that fall over short periods of time can overwhelm city sewer systems.
  • Overloaded sewers can back up through house sewer lines and flow into basements that aren't protected.
  • Even if you or your neighbourhood have never experienced problems with basement flooding, your home can still be at risk.
  • In heavy storms, the total amount of rainfall, and how fast it falls, can vary greatly from neighbourhood to neighbourhood across the city.
    • As an example, the rainstorm of July 16-17, 2005, dumped up to 104 millimetres (4 inches) of rain within 2.5 hours in Fort Richmond, while East Kildonan received half that amount.
  • In case of a basement flooding emergency, contact 311.

What can be done to protect your home?

Exterior house photo Since 1977, we've spent more than $290 million improving the city's sewer system. Along with our improvements, the following protective steps that you can take greatly reduce the risk of sewer backup and basement flooding:

  1. Install a backwater valve and sump pit drainage system
  2. Check and maintain your backwater valve and sump pit drainage system regularly
  3. Improve drainage around your house
1) Install a backwater valve and sump pit drainage system

You should install this equipment if your home doesn’t have these features. For recently built homes, it's the law:

  • new homes built since 1979 are required to have backwater valves
  • new homes built since 1990 are required to have sump pits with pumps
    This applies both to houses built in new subdivisions and to new houses in older neighbourhoods
Typical household backwater valve installation thumbnail image

Click to enlarge

Backwater valve

A backwater valve is a device that prevents sewage in an overloaded main sewer line from backing up into your basement.

  • The valve automatically closes if sewage backs up from the main sewer.
  • A properly installed backwater valve must be placed so that sewage backup is stopped and does not come out through other outlets in your basement, such as sinks, toilets, showers and laundry tubs.
  • With a backwater valve alone, weeping tiles connected to the sewer line can't drain when the backwater valve closes, causing water to overflow into your basement from the floor drain.
Sump pit

A sump pit drainage system includes a sump pit, a sump pump and a pump discharge pipe.

  • The sump pit, set into the basement floor, collects water from the weeping tiles around your basement.
  • The pump pushes the water outside your house through the discharge pipe.
  • Place your sump pump discharge pipe so that it drains somewhere onto your property where water can be absorbed, such as your lawn or flowerbed.
  • Do not allow water from your sump pump to drain directly onto neighbouring properties, lanes, sidewalks, boulevards, streets or into your home's floor drain or plumbing drainage system because this is illegal.
Proper sump pump installation for homes built before 1990

Sump pump illustration

You will need a permit and inspection to install a backwater valve and sump pit. Since part of the basement floor will be dug up and because proper placement of these items is important, we recommend that you use a licensed plumbing contractor.

Check your Yellow Pages for reputable contractors, and ask friends and neighbours for referrals. We recommend that you:

  • Get at least three estimates
  • Ask for and check contractor references
  • Call the Better Business Bureau for a reliability report on contractors
  • Make sure your contractor obtains the necessary information and permits by calling the City's Planning, Property and Development Department at 204-986-5300

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2) Check and maintain your backwater valve and sump pit drainage system regularly

Here are some things to do to make sure that your drainage system continues to operate properly.

Check the operating instructions for more detailed information and safety guidelines, or ask your plumber to explain the details of your system to you.

Backwater valve
  • Make sure that you can get to the valve at all times.
  • Check the valve regularly and remove any material that may prevent the valve from operating properly.
Sump pit
  • Clean the pit each year after freeze-up. Weeping tile drainage may carry small amounts of soil, sand and debris into the pit from around your basement.
  • Some water may remain in the pit and cause a musty smell if it sits for a long time. If so, you can flush the pit by adding fresh water until the pump removes the stale water.
Sump pump
  • Check and test your pump each spring before the rainy season begins, and before you leave your house for a long time. Pour water into the pit to trigger the pump to operate.
  • Remove and thoroughly clean the pump at least once a year. Disconnect the pump from the power source before you handle or clean it.
  • Check the pit every so often to ensure it is free of debris. Most pumps have a screen that covers the water intake. You must keep this screen clean.
  • Check and clean your catch basin / floor drain trap.
Sump pump discharge pipe
  • Check the place where the discharge pipe leaves the house. If the pipe is discharging right against the basement wall, the water will drain down into the weeping tiles and continue to recycle through the system.
  • Check the discharge point regularly to make sure that nothing is blocking the flow.
  • Contact 311 for help if your pump runs frequently in the winter, and ice is causing hazardous conditions.

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3) Improve drainage around your house
  • Build up the ground around your house so that water flows away from your basement walls. Also examine sidewalks, patios, decks, and driveways. These can settle over time and cause water to drain back towards your basement walls.
  • Extend downspouts so that water flows away from your house and doesn't pool next to the basement walls or basement windows. If your downspouts are connected to your home's sewer system, disconnect them.
  • Clean debris from eavestroughs regularly. If they overflow even when clean, replace them with larger size eavestroughs and downspouts.

Illustrations showing improper and proper drainage

Proper drainage helps to...
  • reduce the amount of water flowing to your home's sewer system and to the main sewer system, and lessen the risk of sewer backup
  • reduce water seepage into your home through basement windows and cracks in your basement walls
  • keep the moisture content of the soil around and under your house stable to reduce the chances of cracking and shifting. If water pools next to your basement, it can make its way to the footings that support the basement walls. The increased moisture may cause the soil to swell and the footings to heave
  • extend the life of your sump pump by reducing the amount of work it has to do

Be sure your drainage improvements do not cause drainage problems for your neighbour or affect the grading near the property line. This could be against the City's lot grading by-law. Contact 311 if you have questions about your planned drainage improvements or about the by-law.

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Have you done everything you can?

Contact 311 for more information on the steps you can take to reduce your risk of basement flooding. For information on installing backwater valves and sump pits, contact the Planning, Property and Development Department at 204-986-5300.

Last updated: March 19, 2019