A sanitary sewer is a system of pipes normally located in the street or in public easement that are solely designed to transport sewage to a treatment plant.

The sewer line that carries wastewater from the sanitary fixtures and floor drains inside your home or business to the City's sewer mains is called a sewer lateral. The property owner owns and is responsible for maintaining the sewer lateral from inside the building to the point where it connects with the City Street Main.

Graphic showing the area of City responsibility for sewer laterals

Five key points to remember:

  1. The property owner owns the entire sewer lateral from where it commences inside the building to the point where it connects to the City sewer main.
  2. The property owner is responsible at their own cost, for all maintenance associated with their sewer lateral. Regular maintenance is strongly recommended in order to maintain a properly functioning sewer lateral. Grease removal, flushing of a slow running sewer lateral and removal/cutting of infiltrating tree roots are examples of regular maintenance.
  3. In the event of a blockage in the sewer lateral, the property owner is encouraged to call a plumber or pipe cleaning company to remove the blockage. 
  4. When a problem is suspected in the portion of the sewer lateral under the City Right-of-Way, the property owner is required to provide at their cost, a video inspection of their sewer. The property owner will also be required to locate their sewer lateral with proper measurements, markings (paint and flags) and a Camera Inspection Field Report to assist the City to determine the precise location of the problem.  There are many plumbers and pipe cleaning companies which can provide the property owner with these services. The City will not reimburse the property owner for the costs associated with conducting a video inspection or locating their sewer lateral.
  5. If it is determined by the property owner and subsequently verified by the City, that a blockage in the property owner's sewer lateral is due to a collapsed, broken or deficient pipe under the City's Right-of-Way, the City will schedule and make repairs at the City's expense as soon as possible. The property owner is still responsible to maintain their sewer lateral until the repairs can be made. If it is determined by the property owner that the blockage is in the portion of sewer lateral located on private property, then the property owner is responsible to address the problem at their cost.

If more information is required, please call the Municipal Works Division at 613-930-2787 ext. 2226 (or 613-932-5354 after regular business hours).

 What causes sewer backups?
Occasionally the mainline sewer or the sewer lateral becomes blocked and the sewage is unable to flow; the blockage causes the sewage flow to "backup" or "overflow" to the first upstream outlet, which is most commonly a city manhole, but sometimes may be a low elevation fixture (such as a bathtub drain) in a private address.

The most common causes of backups include:

  • A buildup of grease, debris or foreign objects in the laterals or mains.
  • Partial or complete blockage caused by tree roots.
  • The collapse of old deteriorated sewer pipes.
  • Excess water entering the sewer system from inflow of rainwater during severe wet weather conditions or from illegal drain connections to the sewer system.
 What if my sewer backs up, or I see a suspected sewer overflow in the street?
Please contact the Municipal Works Division at 613-932-5354 and ask for the Sewer Section as soon as you begin to experience a backup or observe an overflow from a sewer manhole into the street. Municipal Works crews will first check the City's sewer main to verify that the pipe is open and sewage is flowing.

If the sewer main is found to be clear, the property owner is encouraged to call a plumber or pipe cleaning company to remove the blockage. When a problem is suspected concerning the portion of the private sewer lateral, the owner is required to provide at their cost, a video inspection of their sewer lateral in order to identify the problem.

The owner must also provide the location of the lateral to assist the city in determining the location of the problem section. You can find many pipe cleaning companies and plumbers to assist with these services.

 How can I do to prevent backups in my sewer lateral?

Regular maintenance is strongly recommended in order to maintain a properly functioning sewer.


  • Collect grease in a container and dispose in the garbage.
  • Place food scraps in the garbage for disposal with solid waste.
  • Place a wastebasket in the bathroom to dispose of solid waste (disposable diapers and personal hygiene products do not belong in the sewer system).
  • Consult a plumber to investigate the condition of your sewer lateral if you have noticed sewage odours within the house, even if you have not experienced a backup or overflow.
  • Consult a plumber to undo any illegal non-sewage plumbing connections to the sewer lateral.


  • Do not pour grease, fats and oils from cooking down the drain.
  • Do not use the sewer to dispose of food scraps.
  • Do not use the toilet as a wastebasket for garbage or chemicals. These items can kill "good" bacteria used in sewage treatment and cost much more to treat.
  • Do not plant trees with shallow, spreading root systems near your sewer lateral. Tree roots seek water sources, such as cracked sewer lines. Once the roots have penetrated the line through cracks, the roots can create a dense mat and trap materials.
  • Do not connect backyard drains, sump pumps and other drainage systems to the sanitary sewer line. It's illegal and can cause the capacity of the mainline to be exceeded during heavy rains.

For additional information on the Waste Water Distribution System Please call 613-930-2787 ext. 2226.


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Municipal Works
1225 Ontario Street, Box 877, Cornwall ON, K6H 5T9

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