Only one fixture is affected
An isolated toilet, sink or shower may be blocked in its trap or branch line. If no other fixture is affected, start by describing it as a localized blockage.
Sewage backing up into the basement
Act quickly, then determine where the backup is actually coming from
A sewer backup is not simply a slow drain. If sewage comes up through a floor drain, toilet, shower or another low point, stop using water and keep people away from the affected area.
SOS Plombiers accepts urgent requests 24 hours a day, 7 days a week, collects the address and details about the symptoms, then attempts to direct the request to a partner contractor based on the type of problem, service area and availability. The assigned company confirms its estimated arrival time, diagnosis, method, price and scope of work before any authorized service begins.
While the water is backing up
The first six steps to limit the risk
- Stop using all water. Do not flush toilets or use showers, washing machines, dishwashers or faucets.
- Keep children and pets away. Treat the backed-up water as potentially contaminated and avoid any unnecessary contact.
- Do not touch anything electrical. If the water reaches an outlet, appliance or electrical panel, keep your distance and contact the appropriate emergency services.
- Do not add any chemical drain cleaner. The product may remain in the backed-up water and expose occupants or the person who opens the pipe.
- Document the situation without putting yourself at risk. Photos, videos, the time the problem began, weather conditions and affected fixtures can help the contractor and insurer.
- Describe the order in which the symptoms appeared. Indicate which point reacted first and what triggers another backup.
SOS Plombiers coordinates a plumbing service request; water extraction, decontamination, restoration and insurance claim management may require other service providers. Contact your insurer promptly to determine what information should be documented. If there is an immediate danger to people, call the appropriate emergency services.
The symptom guides the initial assessment
Is it a localized blockage, the main drain or the sewer system?
The location where the water appears does not confirm the cause on its own. The number of affected fixtures, when the backup occurs, the weather, access to the pipe and the building’s history help determine an initial direction without claiming to provide a diagnosis remotely.
Several drains react at the same time
A toilet that gurgles while the washing machine drains, or several fixtures that slow down at the same time, may indicate a shared branch line or the main drain.
Sewage comes up into the basement
Sewage coming up through a basement floor drain, toilet or shower corresponds to the primary purpose of this page. Stop using water and request prompt assistance.
The problem keeps returning or the pipe is suspected
Roots, a displaced joint, a crack, a collapsed section or persistent buildup can cause recurring problems. A camera can document an accessible pipe after the necessary clearing has been completed.
Before a complete overflow occurs
Signs that indicate greater urgency
- greywater or sewage around the floor drain;
- basement toilet water level rising or overflowing;
- shower or bathtub filling when the washing machine drains;
- gurgling in several fixtures or on different floors;
- sewer odour accompanied by abnormal drainage;
- backup occurring during or after heavy rainfall;
- the problem recurring in the same location after a previous drain cleaning.
Same symptom, different causes
Why can a sewer back up into a building?
A backup may originate from the private sewer line, the plumbing configuration, a protective device or an overloaded municipal sewer system. The problem should not automatically be blamed on the municipality, roots or the backwater valve before the indicators and location of the defect have been assessed.
Blocked sewer line
Grease, wipes, paper, objects, buildup or roots can restrict or completely block the flow. Restoring drainage does not prove that the pipe is intact.
Possible structural defect
An open joint, crack, displaced section, sag or misalignment can trap waste and cause the problem to recur.
Unsuitable or defective backwater valve
A backwater valve that is blocked, inaccessible, poorly maintained or unsuitable for the configuration may not provide the expected protection. Its type and location must comply with the requirements that apply to the building.
Heavy rainfall and an overloaded sewer system
An intense rainfall event may temporarily exceed the system’s capacity. The building should nevertheless be assessed to distinguish the source and verify its protective devices.
From the initial call to flow verification
What a properly assessed service call should clarify
1
Assess the urgency
Presence of sewage, rising water level, affected fixtures, electrical hazards, building type and access.
2
Confirm the partner
The contractor identified based on the service required and the area communicates their estimated availability and terms.
3
Assess the situation on site
The symptoms, cleanout, backwater valve, probable pipe route and apparent condition help determine the method.
4
Approve the price and method
The fees, cable equipment, high-pressure cleaning, camera inspection and any additional work must be explained before being carried out.
5
Restore flow
The method is adapted to the access, diameter, material and condition of the pipe, as well as the type of blockage.
6
Verify and document
Ask how the flow was verified, what was observed and what would justify follow-up work.
The tool should follow the diagnosis
Drain clearing, cleaning, camera inspection or repair: what does each step address?
| Method | Possible use | Limitation to understand |
|---|---|---|
| Motorized cable or auger | Clear certain blockages in an accessible branch line or main drain. | Creating a passage does not always clean the pipe walls and does not repair a crack or sag. |
| High-pressure cleaning | Remove certain deposits, sludge, grease or roots when the condition of and access to the pipe allow it. | The pressure, flow rate and nozzle must be appropriate; it is not automatically the best choice for every pipe. |
| Camera inspection | Locate or document a recurring problem, roots or a defect in an accessible pipe. | The camera does not clear the drain. A complete blockage may need to be removed before useful images can be obtained. |
| Pipe repair | Correct a confirmed structural defect based on its location, extent and the building’s configuration. | Excavation or replacement should not be assumed before the defect and responsibilities have been documented. |
| Backwater valve inspection | Check its accessibility, cleanliness, movement and configuration after a backup. | A backwater valve does not clear a blocked private sewer line and must be installed in the correct location in accordance with applicable requirements. |
Prevention in Montreal
In Montreal, prevention depends as much on the building as on the rainfall
Ville de Montréal notes that a backwater valve must remain accessible and be maintained. Under certain conditions, it also offers home inspections to property owners who have experienced a sewer backup or flooding, who are located in a vulnerable area or who have filed a claim. The inspection results in a personalized report; the City does not carry out the corrective work.
These resources apply to Montreal. In Laval, Longueuil and other Greater Montreal municipalities, check local requirements before modifying a building drain or adding a protective device. A proper assessment distinguishes a blockage in the private sewer line, backflow from the municipal sewer system, surface water, foundation drainage and the condition of the backwater valves.
Prevent without confusing the equipment
Backwater valves, catch basins and sump pumps do not serve the same purpose
Backwater valve
It is designed to limit sewage from flowing back through the protected piping. It must be suitable for the installation, accessible and maintained.
Catch basin and pump
These instead manage certain types of water collected around the foundation or in the sump pit. A sump pump does not replace protection for the sanitary sewer system.
Main sewer line
A damaged or repeatedly blocked pipe may require a targeted repair. The defect should be documented before the work is selected.
The CMMTQ distinguishes between several types of backwater valves and states that their use depends in particular on the building drain, the number of dwelling units and municipal requirements. Some municipalities do not permit installation on the main building drain. The appropriate choice must therefore be confirmed for the building. See the PL-12 technical sheet on backwater valves and the PL-58 technical sheet on normally open backwater valves.
Residential, multi-unit and commercial properties
The building changes access, responsibilities and urgency
House and condo
Specify the affected level, the basement fixtures, any recent work, the history of sewer backups and any available reports.
Plex and rental building
Indicate whether only one unit or several floors are affected. The owner, condo corporation or property manager may need to authorize access to common areas.
Business and restaurant
Describe the affected drains, the impact on operations, access hours and health requirements. Also see the commercial plumbing page.
A useful price reflects the actual problem
What factors determine the cost of a sewer backup?
A generic price can be misleading when the access, depth of the blockage, condition of the pipe and work required after flow is restored are unknown.
- address, time and level of urgency;
- number of fixtures and type of building;
- cleanout and accessibility;
- pipe diameter, material and route;
- cable equipment, high-pressure cleaning, camera inspection or pumping required;
- testing, report and additional work.
Coverage based on the address and availability
Sewer backup requests throughout Greater Montreal
Coverage and response times vary depending on the address, time, nature of the backup, access conditions and the partner contractors available to accept the request.
Montreal and the West Island
Houses, plexes, condominiums and businesses depending on the area.
Laval and the North Shore
Requests may be directed to a partner in Laval and several cities north of Montreal.
Longueuil and the South Shore
Residential, multi-unit and commercial requests depending on local availability.
Answers before requesting service
Frequently asked questions about sewer backups
What should you do immediately if sewage backs up into the basement?
Stop using water, keep people and pets away, avoid all contact, do not touch anything electrical if the floor is wet, and document the situation without putting yourself at risk. Then request prompt assistance.
How can you distinguish a clogged drain from a sewer backup?
A single slow or blocked fixture may indicate a localized obstruction. When several fixtures react at the same time or sewage comes up through the lowest point, a shared pipe, the main drain or backflow from the municipal sewer system should be considered. The diagnosis must be confirmed on site.
Are urgent requests accepted 24/7?
Yes. SOS Plombiers accepts urgent requests 24 hours a day, 7 days a week. Availability and the estimated response time are then confirmed by the partner contractor based on the address, time and nature of the problem.
Is a camera inspection always necessary?
No. It may be useful after a recurring blockage has been cleared, when roots or a defect are suspected, or when the pipe must be documented in a report. A complete blockage may prevent useful images from being obtained before the drain is cleared.
Does a backwater valve prevent every sewer backup?
No. It protects the piping to which it is properly connected when it is suitable, accessible and functioning correctly. It does not clear a blocked private sewer line and does not replace other measures required for surface water or foundation drainage.
Who performs, invoices and warranties the work?
SOS Plombiers receives, assesses and coordinates the request. The assigned partner contractor confirms its availability, performs the diagnosis and authorized work, and then issues the invoice. Any applicable warranty must be communicated by that company.
How much does a sewer backup service call cost?
The price depends on factors such as urgency, access, the number of affected fixtures, the location of the blockage, the equipment required and any additional work. The partner contractor must communicate its fees and the applicable terms before authorization.
Eaux usées qui remontent maintenant?
Décrivez les symptômes avant de choisir la méthode
Indiquez l’adresse, le bâtiment, les appareils touchés, le moment où le problème a commencé et les tentatives déjà faites. SOS Plombiers tentera d’orienter la demande vers un entrepreneur partenaire approprié selon le besoin, le secteur et les disponibilités.
Le diagnostic final, le délai, le prix, la méthode et les travaux sont confirmés par l’entreprise partenaire assignée.
Expériences de clients servis par le réseau
Avis associés à SOS Plombiers
Les avis ci-dessous sont agrégés par TrustIndex à partir des profils associés à SOS Plombiers. Ils peuvent concerner différents services et entrepreneurs partenaires et ne garantissent pas le résultat, le délai ou le prix d’une prochaine intervention.