The sanitary sewer system collects wastewater from your home through a pipe called a sanitary lateral. This lateral carries wastewater from toilets, washing machines, dishwashers, showers and sinks to the sewer main, which carries wastewater from other homes and businesses to the City's wastewater treatment facility.
Foundation drains collect groundwater from around the foundation of your home and are usually connected to the storm sewer by a storm lateral. In some older homes, these drains are connected to the sanitary or combined sewer by a sanitary lateral, or are not present. Water from rainfall events and snow melts are also collected by storm sewers and directed to nearby watercourses or storm water management ponds.
While the City regularly cleans, inspects and repairs the sanitary and storm sewer systems, unanticipated problems can occasionally occur, causing increased water levels in the sewer (or surcharging).
Alternate types of sewer systems
In some older homes, foundation drains are connected to the sanitary or combined sewer by a sanitary lateral, or are not present. Basement flooding caused by sewer backups can originate from different sources depending on the type of sewer system in your area.
Please note: New buildings (or “infill”) in older areas of the city may have more modern sewer connections than described below.
Partially separated area
- Older buildings with foundation drains connected to the sanitary sewer.
- Storm sewers only have street catch basins connected.
- Basement flooding risk is generally from the sanitary sewer.
Partially separated area (former combined sewer area)
- Older buildings with no foundation drains.
- Catch basins are connected to the storm sewer
- Basement flooding risk is generally from the sanitary sewer.
Combined sewer area
- Older buildings with no foundation drains present.
- No storm sewer is present.
- All sanitary laterals, foundation drains and catch basins connected to one combined sewer.
- Basement flooding risk is generally from the combined sewer.
Responsibility for sewer laterals
- The City is responsible for the portion of the sanitary and storm sewer laterals from the property line to the street.
- The homeowner is responsible for the portion of the sanitary and storm sewer laterals from the property line to the home.
- There may also be shared responsibility if a lateral requiring repair or replacement crosses the property line.
Causes of backups and flooding
Backups and flooding can occur as a result of:
Blockage of the lateral
If the lateral from your home becomes blocked, sewage from inside your home may back up into the basement. The blockage may be due to:
- Accumulation of grease, paper, kitchen waste or other foreign objects
- Presence of tree roots (private or City-owned trees)
- Collapse, misalignment or other structural defects of the lateral
Surcharging of the City’s sewer main
If the sewer main, generally located under the street, is blocked or damaged, sewage may enter your home due to increased water level or surcharging in the City’s sewer system. Sewer surcharging may be due to:
- Collapse or other structural defects.
- Blockage by waste and debris.
- Heavy rainstorms or spring runoff.
- Construction activities in the area.
Melting snow and ice can leak through cracks or joints in your basement walls or floor.
River flooding sometimes occurs in some areas of the city. Each spring the City clears ice from the Rideau River to prevent serious flooding.
To find out if you live in Ottawa's 1-in-100 year flood plain, consult the City's interactive map.
Tips to prevent basement flooding
Residents can help prevent basement flooding with a few simple changes around the home:
- Seal window wells and cracks in floors, walls and the foundation.
- Slope ground away from the foundation to allow rainwater to flow away from the home.
- Direct downspouts from eaves troughs away from the foundation (minimum of 1.2 metres) or to a rain barrel(s).
- Disconnect downspouts from the sewer system or foundation drains.
- Ensure foundation drains direct water to the storm sewer or sump pump. Foundation drains should not be connected to the sanitary sewer.
- Ensure the sump pump is connected to the storm sewer or discharges to the ground at least 1.2 metres from the foundation.
- Install protective plumbing devices, such as backwater valves which protect against surcharging in City sewers. The City’s Residential Protective Plumbing Program offer rebates to qualified homeowners.
- Maintain existing protective plumbing devices according to the manufacturer’s instructions. A protective plumbing device should be maintained periodically or before a forecasted heavy rainfall to ensure it is free of debris, functioning properly and that cleanout caps and access covers are firmly secured.
- In older homes, especially those with cast iron pipes, additional maintenance may be required, as rust can accumulate at the hinge and prevent proper closure of the backwater valve during a surcharge event.
- For more tips on backwater valve maintenance, refer to a video on Backwater Valve Maintenance from the Institute for Catastrophic Loss Reduction.
For more tips on preventing basement flooding, refer to the Handbook for Reducing Basement Flooding from the Institute for Catastrophic Loss Reduction.
What to do if your basement has flooded
Recommended homeowner response to basement flooding:
- Check the toilets and sinks for blockages.
- Wearing appropriate protective clothing, clear any blockages to ensure proper flow.
- If this does not resolve the issue, call 3-1-1. The City has expert staff on duty at all times who will respond as soon as possible to these situations. If requesting City assistance, ensure someone 18 years or older is at home to meet City staff.
- Locate the sewer clean-out caps. Do NOT attempt to open. Clean-out caps are usually located in the basement floor at the front of the home (near the water meter). Ensure an area at least one metre on all sides of the clean-out is free from obstructions (boxes, furniture) to provide access to City staff.
- Avoid using fixtures and appliances which require water, until after the issue has been resolved, as any water sent down the drain may end up in your basement.
Do NOT enter the flooded area until a qualified professional has determined it is safe to enter.
If the flood water level is threatening any gas-fired equipment such as a furnace, hot water heater or stove, contact Enbridge Gas.
If the flood water level has reached any plug, electrical outlet, extension cord or electrical appliance such as a baseboard heater, contact Hydro Ottawa.
More information on flood safety can be found from the Electrical Safety Authority.
Bacteria or viruses
Basement flood water may contain sewage from the sanitary sewer. Flood water contaminated with sewage may contain bacteria and viruses which can affect your health and the health of your family. Be sure to wear protective clothing such as rubber boots, gloves, safety glasses and a facemask, and wash thoroughly after any contact with flood water or items which may have been in contact with flood water.
The following links provide information on preparing for a potential flood; protecting yourself and your family during a flood; and restoring your home after a flood.
Contacting your insurance company
Your insurance company will be able to advise you regarding standard clean-up and claims procedures, along with contractors to contact. Generally,
- Understand your coverage and what type(s) of flooding damage are covered.
- Photograph and document damaged items or items which will need to be replaced.
- Retain receipts for any emergency and repair work, along with replacement items.
For more information on home insurance, visit the Insurance Bureau of Canada website.
City response to basement flooding
- City staff will inspect the sewer main near your home to determine whether or not it is functioning normally. If there is a problem, it will be fixed as soon as possible.
- If the problem is not related to the sewer main, City staff can help you identify the problem, if resources are available.
- If the problem is in the home’s drain system, the homeowner will be advised to contact a plumber.
- If the problem is related to either the sanitary or storm lateral, repairs may be the homeowner's responsibility, City's responsibility, or a shared responsibility. Responsibility can only be determined after City staff have reviewed all of the available information.
Preventative sewer maintenance list
The City maintains a list of properties confirmed to have experienced a sewer backup caused by City-owned tree roots or structural defects on a City-owned portion of the sewer that cannot readily be repaired.
As part of its Preventative Maintenance Program, the City offers a sewer maintenance service annually (or as otherwise modified) to these impacted properties to ensure the proper function of the sewer and help prevent sewer backups.
For further information and eligibility requirements, please contact 3-1-1.
Responsibility for the repair costs
The cause and location of the blockage generally determines who is responsible for the cost of removing the blockage or repairing the lateral. Generally, lateral blockages are the responsibility of the homeowner, unless the blockage is due to City-owned tree roots or the damaged portion is on City property. For more information on repair costs and responsibility for those costs, refer to the Sewer Connection By-law, as amended.
If the flooding is due to a blockage on the private portion, a contractor must be contacted. As a homeowner, there is the option to select a contractor of your choice, or the City's contractor. Work not related to removal of a blockage such as repair, relining and replacement are billed directly by the contractor to the homeowner.
If, during the course of the repair work, it is determined that the blockage is located on City property, the homeowner will not be charged for the repair work. If payment has already been made for any work, the homeowner will be reimbursed. The reimbursement amount will be up to the amount typically paid by the City to its contractor for the same service. Requests for reimbursement should be directed to the City's Claims Unit.
In some cases, repair costs may be shared between the City and the homeowner.
Making a claim
Homeowners who have incurred damage to their home or its contents should contact their insurance company for assistance. Typically, your insurance company will submit a claim to the City for investigation/response on your behalf. Claims can be submitted to the City’s Claims Unit.
For more information, please contact our general claims line at 613-580-2655 or by email at email@example.com.