Private or public sewer responsibility is a common question after sewage backs up into a basement. However, the place where water appears cannot establish who must maintain the connection, approve excavation or compensate someone for damaged belongings. Those decisions depend on different information. A clear record, sent through the correct municipal process, gives each person the facts needed to examine the situation.
This guide explains how to prepare that record in LaSalle and across Greater Montréal. It separates the plumber’s findings from the municipality’s assessment and the insurance claim. Montréal, Dollard-des-Ormeaux and Longueuil appear as local examples because their published procedures differ. Their instructions should not be treated as one regional policy. You can begin with incomplete information, provided you identify what remains unknown instead of filling the gaps with assumptions.
Key points
- Location is only part of the answer. A pipe beneath the street does not automatically make the City responsible for every expense.
- Check the correct authority. Use the property’s municipality and, in Montréal, its borough.
- Explain the documentation needs in advance. An inspection intended for a municipal file must meet the local requirements.
- Keep separate follow-ups. Requesting sewer repairs and claiming compensation for damage are different processes.
1. Private or public sewer responsibility: identify the pipe first
The sewer connection carries drainage from a building to the municipal network. The main sewer in the street receives connections from properties in the area. Inside the building, several fixtures can share drainage before the pipe leaves the foundation. Water coming out of a basement floor drain therefore identifies an outlet. It does not necessarily identify the section causing the backup.
Ask the professional to name the pipe shown in the inspection sketch. “Building sewer connection” is more precise than “City sewer” when the description simply concerns a pipe heading toward the street. Also distinguish wastewater drainage, stormwater drainage and the drinking-water service. They perform different jobs. An explanation about the water supply line should not be used to assign responsibility for a sewer problem.
Montréal’s overview of plumbing and sewer work, in French says owners maintain their complete sewer connection to the municipal sewer, including beyond the property boundary. It distinguishes this maintenance from possible City involvement in certain structural repairs on public property. As a result, dividing everything into “my yard” and “the street” can produce a misleading answer.
When discussing the location, keep the terms used in the report. If you do not understand a label, ask for an explanation before repeating it to another service. A precise description can travel from the inspector to the municipal reviewer without becoming a different diagnosis along the way.
2. Separate three decisions before assigning costs
First, consider the current incident: how can people remain safe and drainage be restored where possible? Next, examine permanent work: which section needs attention, who may perform the work and what approvals are required? Finally, consider damage: does an insurance policy or a municipal claim apply? One event can create all three follow-ups, with different outcomes for each.
| Follow-up | Question to ask | Record to keep |
|---|---|---|
| Immediate intervention | What was cleared or made usable? | Detailed invoice and instructions for resuming use |
| Permanent repair | What defect was observed, and where? | Video, report, sketch and municipal response |
| Property damage | Who reviews the claim, and under which deadline? | Notice, delivery confirmation, photographs and inventory |
A paid plumbing invoice does not establish that a municipality has accepted responsibility. Opening a municipal file does not authorize excavation. Similarly, public repair work does not settle compensation for belongings in the basement. Record the actual status of each process instead of describing the whole situation as “the City is handling it.”
This distinction also helps when two people discuss the same event. An adjuster may ask about damaged flooring while a municipal reviewer asks about a pipe defect. Send each person the relevant information, and keep their file numbers separate so that a reply about one issue is not mistaken for a decision about the other.
3. During a backup, safety comes before paperwork
If water is still rising, call to have the urgency assessed and stop uses that send water into the affected drainage. Tell other occupants what is happening. Do not recreate the backup to obtain a better recording. Our sewer backup service page explains the intervention request. This guide focuses on the information and follow-ups that may be needed around that intervention.
Do not walk through water to reach an electrical panel or retrieve documents. Québec’s flood safety guidance, in French, warns about electrical hazards when a basement fills. It directs people to contact Hydro-Québec at 1 800 790-2424 to have service interrupted when water begins entering. Call 911 for an immediate danger to people. Photographs can wait until the situation is safe.
The need for evidence is never a reason to open a cleanout on a potentially full pipe or lift a street maintenance-hole cover. Instead, describe the access you know about and any obstacles. If all the records are in an inaccessible basement, start with the address, the current condition and a telephone number. The missing documents can be discussed afterward.
4. Find the process that applies to the address
Write down the complete civic address, unit number and municipality. “West Island” and “South Shore” describe areas, not single authorities. LaSalle is a Montréal borough, while Dollard-des-Ormeaux publishes its own procedure. A familiar neighbourhood name is therefore not enough to choose the right application or the right municipal office.
Next, find the official municipal information. In Montréal, select the borough within the relevant procedure. Confirm the receiving department, current form and accepted way to send files. Also ask whether a municipal file number should be obtained before the camera inspection. Note the date, department and answer. This can prevent paying for documentation prepared to another municipality’s specifications.
Keep a dated copy of the instructions you used. If a form changes during the follow-up, you will be able to explain which requirements you were given. That copy helps organize the exchange; it does not override newer instructions from the responsible service. Before sending personal information, check the current recipient details on the official website.
Use a short list of unanswered questions rather than sending several nearly identical requests. For example: which application applies, which inspection information is missing, and who confirms the next step? A focused question is easier to answer than a request to “take over everything” without identifying the work or decision involved.
5. What three municipal procedures illustrate
Montréal, including LaSalle
The Montréal sewer connection repair process concerns qualifying structural defects on public property. Clearing an obstruction or cutting roots is different. Select LaSalle for the applicable submission instructions. Ask the borough to assess eligibility; neither a private inspection nor a defect beneath the street guarantees City work or reimbursement of costs already incurred.
Dollard-des-Ormeaux
Dollard-des-Ormeaux’s sewer backflow procedure begins with a professional intervention. When the public side appears involved, residents open a file and provide the recording with a written report. The City specifies a camera-counter starting point at the outside of the foundation. Share those instructions before the visit. A recording measured from somewhere else may require clarification or another inspection.
Longueuil
Longueuil’s procedure, in French, calls for contacting 311 and opening a file before the inspection when the building connection is suspected. It requests clear footage displaying the date, time and distance. Neighbouring properties with problems inform the report, but do not establish a diagnosis. The different sequence illustrates why local instructions should be checked first.
These examples do not describe every municipality in Laval or on either shore. Obtain the instructions for any other address separately. Do not turn a condition published for one city into a universal rule for Québec properties.
6. Build a factual incident timeline
Create a one-page summary that another person can understand without reading your entire email history. Start with the first observation, then add calls, visits and changes in the situation. Distinguish the estimated time the incident began from the time you discovered it. An honest approximation is more useful than an exact time chosen without evidence.
- Incident: date, approximate time, room, fixture and water movement already observed.
- Context: appliance use, rainfall you observed or information someone reported, without automatically treating it as the cause.
- Intervention: company, arrival time, access used and work described on the invoice.
- Result: restored drainage, an ongoing problem or a section that could not be inspected.
- Follow-up: department contacted, file number, requested document and next action.
Identify the source of each statement. “The tenant reported water rising around 6 p.m.” differs from “I watched it rise at 6 p.m.” If a neighbour reports a problem, note only what they agree to share. You do not need their insurance file or invoices. Keep your summary focused on your property and relevant observations.
Our guide to one blocked drain or several helps describe fixture symptoms before a diagnosis. Here, the timeline connects technical findings with administrative steps. It should not assign responsibility using symptoms alone. If a later inspection changes the explanation, add that finding with its date instead of rewriting earlier observations to fit the new explanation.
7. Request a usable camera inspection and report
When booking, explain that the inspection may support a municipal application. Send the official requirements and ask whether the company can provide the requested documentation. Clarify what the proposed price includes: clearing, recording, written report, locating and delivery of files. A basic blockage-clearing visit and a complete documentation service may involve different work.
The RBQ licence verification service lets you check the contractor and licence categories. Use the legal business name and licence number of the company being hired. This check does not replace confirming the municipality’s documentation requirements. Our drain camera inspection page explains the service request.
Questions about the written findings
Ask for an address and inspection date that identify the visit unambiguously. The report should make the starting access, direction of travel, measurement units and visible sections understandable. You should be able to connect a written observation with the corresponding video location. “Something wrong toward the street” gives the reviewer less to work with than an identified observation and its limits.
Also ask what remains unknown. If the camera did not reach the main sewer, the record needs to say so. A section hidden by water is not the same as a section found free of defects. The sketch, camera route and surface location should agree. Distance travelled through a pipe does not automatically equal horizontal distance measured from the sidewalk.
Safety before clearing the way for the camera
Leave the clearing method and precautions to the professional. Énergir warns about possible gas-line cross bores during mechanical or high-pressure clearing outside building walls. Its process includes checking with Info-Excavation. Mention previous interventions and do not attempt to force open the pipe yourself to make the inspection faster.
8. Organize evidence and preserve the original files
Keep the original video, final report, sketch, photographs and invoices together. Save a second copy elsewhere. Give files simple names containing their date and document type. Several documents called “final report” without a version date make later exchanges harder. If an inspector issues a correction, retain the earlier version and identify clearly which document replaces it.
Before sending the files, open them on another device if possible. Check that the recording plays, all report pages are included and sharing links lead to the intended documents. Avoid compression that makes the distance display unreadable. Ask about accepted formats and transfer methods. A department receiving technical inspection footage may have different rules from a claims office.
A short index can identify document A as the summary, B as the report, C as the recording and D as photographs. In your message, say which attachment answers the outstanding question. A few relevant, organized files are easier to review than a large group of almost identical photographs. Remove unrelated information about other occupants before sharing documents.
Keep the evidence and your explanation separate. A screenshot with your own arrow can help explain a question, but label it as an annotated copy. Preserve the original image beside it. This makes it clear which information came from the inspection and which note was added later by the owner.
9. Submit a clear request and confirm receipt
The covering message should identify the building and the decision being requested. Avoid stating that responsibility is settled when the application is asking for an assessment. Adapt this example to the official form and the receiving department’s instructions:
Subject: [address] — sewer connection review — file [number]. A backup was observed on [date]. [Company] attended on [date]. Attached are the report and sketch, with a link to the recording. The report describes [exact finding] at [reference shown]. The section [description] could not be inspected. Please confirm receipt, any missing documents and the next step. The current situation is [drainage usable or backup continuing].
Keep submission confirmations and replies. When following up by telephone, quote the existing file number instead of creating another identical request. Ask exactly which item is missing and where it should go. If conditions become urgent during the review, report the change promptly. A complete application does not protect the building from another backup.
After a telephone conversation, write down what was agreed and the action assigned to each person. If an instruction is unclear, ask for written confirmation. Record a promised review date as a review date, rather than a scheduled repair. Those are different milestones and may depend on additional findings.
10. Before approving repair or excavation work
Have the proposed section, supporting findings and required approvals explained. If a municipal assessment is underway, ask how it relates to the private work. Keep a written description of who handles each step. A recommendation to repair is not authorization to work on public property. Likewise, a quote should identify its scope without assuming that another organization will pay it.
Montréal’s permit procedure for water and sewer connections contains borough-specific details. For a LaSalle project, confirm the requirements with the borough before work starts. The LaSalle permit process, in French, explains the local assistance available. A general permit page should not be read as proof that every plumbing visit requires the same authorization.
Arrange underground infrastructure locating before digging. Info-Excavation explains that not every network owner belongs to its service, so other affected owners may need to be contacted directly. Ask who will make those requests and retain the responses. Our sewer line repair and excavation page covers questions about the proposed work.
11. Damage, insurance and claims need a separate follow-up
Contact your insurer promptly when belongings or building materials are affected. Infoinsurance explains that coverage depends on the policy and added protections. Ask what photographs, invoices and evidence should be kept, and how contaminated belongings should be handled. Do not keep a hazardous item solely to prove its value; obtain instructions for documenting it safely.
A repair application does not replace a notice of claim. Montréal specifies a 15-day filing period for material damage claims and says City responsibility is not automatic. Check applicable deadlines and submission channels immediately. Do not wait for an inspection to finish before asking about them. Seek qualified legal help promptly if you are uncertain about your rights or a deadline.
Maintain a separate expense list for intervention, inspection, pipe repairs, cleaning, materials and belongings. Include dates, suppliers, invoices and payments. This organization helps answer questions without assuming which amounts will be accepted. Mark estimates as estimates, and distinguish them from amounts already invoiced or paid.
Frequently asked questions
Does a defect beneath the sidewalk automatically belong to the City?
No. The pipe, type of problem and applicable municipal conditions need to be identified. Footage showing a problem toward public property does not decide maintenance, repairs or compensation by itself. Obtain a documented location and have the appropriate authority review the information.
The camera stopped at an obstruction. Is the report useless?
It can document the point reached and the inspection limit. However, it cannot describe the unseen section beyond that point. Ask the professional what information remains missing and ask the municipal department whether more documentation is needed. That single limitation cannot establish that the entire connection is sound or broken.
Who prepares the file for a condominium or rental property?
Identify one contact to coordinate with the owner, manager or co-ownership syndicate. Confirm who can authorize access and work. Occupants can provide observations, but the building’s property documents and arrangements must be examined before costs are assigned between different parties.
What if another backup occurs while the application is being reviewed?
Report the new active condition, protect people and request an assessment of the intervention needed now. Add the date and new findings to the existing record. A file number does not guarantee safe drainage or immediate attendance. Ask for instructions that reflect the current condition.
Prepare the next step
Call Plomberie LaSalle at 514 312-3198 with the address and current situation to arrange an assessment. Confirm availability and explain any municipal reporting needs before the visit. Use the Contact page for a planned request. Explore our plumbing tips and the Blocked drains and toilets category for related guidance.
Official and specialist sources were consulted on November 4, 2026 and are linked where discussed. The filing examples and message template are practical tools. Local requirements, policy wording and the facts of the individual property still need to be checked.