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Sump Pump

Do you have a sump pit and sump pump in your basement?  Not sure?  Most homes in London constructed after 1985 have a sump pit and sump pump in their basement.  Sump pumps are typically installed where gravity drainage to a municipal storm sewer is not practical. 

Sump pumpWhat is a Sump Pump?

A sump pump is a pump that is used to protect the basement from flooding by removing water from around the basement foundation.  The sump pump is usually positioned in a hole in the basement floor (about the size of a beach ball), also known as the sump pit, and discharges the water.  Depending on the home, the discharge water from the sump pit can be through a pipe in the wall of your home into the yard or to the storm sewer.  Sump pumps should NOT discharge to the sanitary sewer system (contravention of Drainage By-law WM-4).

Where Does the Water Come From?

Where you live and the type of soil on your property can affect how much water is in the ground.  This is referred to as groundwater.  The water is filtered through the ground, collected in the weeping tiles and directed to the sump pit.  Generally, when it rains, more groundwater is produced which increases the risk of water entering your basement.  When the sump pit reaches a predetermined level (using a sump pump float) the sump pump will come on and discharge the excess water.

Sump pump discharge to the lawnWhere Does the Water Go?

Weeping tiles collect the water that has made its way into the ground and around the foundation.  Some weeping tiles are connected to a sump pit.  When the sump pit fills with water and reaches a predetermined level, the sump pump then turns on and discharges the groundwater either directly into the storm sewer system or through a pipe in the wall of your home into the yard, away from the foundation.

The City's Basement Flooding Grant Program helps homeowners disconnect their weeping tiles from the sanitary sewer system, and install a sump pit and backwater valve.

Discharging to the Yard

If your sump pump discharges to the yard there are a few things to consider.

  1. Similar to downspouts from your eaves trough, the sump pump discharge should be directed away from your house, preferably 1.8 meters (6 feet) from the wall of the house to a grassed area.
  2. Ensure that the lot grading around the house is sloped away from the home to decrease the risk of the making its way back into the weeping tile system or directly into the basement.
  3. Keep in mind that the discharge can not negatively impact neighbouring properties, including City property to comply with the Drainage Bylaw WM-4.

How Noisy is a Sump Pump?

The sump pump only makes noise when it is running. It is relatively quiet.  The amount of noise it makes would be comparable to your refrigerator.  Installing a cover over your sump pump will not only reduce the noise level it will also prevent people or animals from accidently falling into the sump pit.

How Much Hydro Will the Sump Pump Use?

The amount of time the sump pump runs will determine how quickly the sump pit fills with groundwater from the weeping tiles.  Wet weather will cause the sump pump to run more frequently than during dry weather.  If there has been rain for several days there will be more groundwater than during a dry spell or short rainfall event.

A typical minimum size for sump pump is a capacity of 1/3 hp or 800 watts.  Larger sump pumps are available (1/2 hp, 3/4 hp).  Based on the sump pump operating about an hour per day (turning on 2-3 times per hour, at 1 minute run time each), it will cost the home owner approximately $40 per year based on 2017 London Hydro rates (at the peak rate).

Battery Back-up

There is a possibility that during a thunderstorm the hydro to your home may be interrupted or unavailable. Having a battery back-up system for your sump pump will allow the pump to run for a limited amount of time when hydro is not available.

Secondary Sump Pump Using City Water

Some residents and businesses may have elected to install a secondary sump pump through a connection to the City’s potable water supply in their homes.  The control valves that operate the secondary pumps should be checked from time to time to ensure they are working correctly.  Some residents have had incidents where large amounts of tap water have passed through the sump and out into the storm sewer or across their lawns.  This water has also passed through the water meter and they are then charged for the water and required to pay the bill.

Sump pump floatSetting the Float

The sump pump will have a device on it called the float, to let it know the level of water in the sump pit.  When the float reaches a predetermined level, the sump pump starts and pumps the water out of the pit.  The trick is to set the level of the float high enough so your pump isn't running all the time but low enough to be able to handle the water entering the pit.  It may take a few tries to get it where you want.

Test your Sump Pump

It is a good idea to regularly test your sump pump, especially if it does not run very often or not at all.  Take a bucket of water and slowly dump it into the sump pit.  The sump pump should turn on when the float reaches a predetermined level.  If the sump pump does not come on, "trip" the float to see if it comes on.

Sump pump discharge making its way down the driveway and onto the sidewalk then freezing.  This increases the safety risk to pedestrians and vehicles.Icing

Avoid discharging your sump pump to the sidewalk or driveway to comply with the Drainage By-law. During the winter months the sump pump can still regularly discharge water to the ground surface. When the water makes its way to the sidewalk or the road and freezes there is a risk of slipping for both pedestrians and vehicles.



The City of London has a Basement Flooding Grant Program that helps selected homeowners install a storm private drain connection/storm building sewer.  This is a pipe that directs the sump pump discharge to the storm sewer under the road (if a storm sewer is available). This removes the sump pump discharge from the ground surface, alleviating icing and/or erosion issues.



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