Immediate danger?
Do not enter standing water if electrical equipment, outlets or the building structure may be affected. Leave the area and call 911 when there is an immediate threat to safety. This guide is general information, not emergency or insurance advice.
First 15 minutes
Stop using water
Do not flush toilets, run taps, use appliances or send more water into the drainage system.
Keep people and pets away
Wastewater can contain contaminants. Avoid skin contact and do not let children or pets enter the affected space.
Document what is happening
If it is safe, take photos and video of the source, water level and damaged items before cleanup. Contact your insurer promptly.
Look outside safely
From a safe location, check for an overflowing manhole, street flooding or similar problems at neighbouring properties. Do not approach displaced covers.
Public sewer issue or private drain?
Signs of a public-system issue
An overflowing manhole, collapse around a public drain or water overflowing onto a sidewalk should be reported to Montréal. The city directs people to call 311 for situations requiring an immediate response.
Signs of a private-line blockage
Backup limited to one property, multiple fixtures gurgling together or wastewater returning through the lowest floor drain can point to the building's drain or sewer connection. Stop water use and arrange a drainage diagnosis.
The City of Montréal states that an owner is responsible for unblocking a sewer connection and cutting roots that block the drain, including in circumstances described by its by-law. A camera report and recording may be needed if a connection repair request is made.
After the flow is stopped
- Follow your insurer's instructions before discarding damaged material.
- Use qualified cleanup help for contaminated water and affected porous materials.
- Ask what evidence identifies the cause: obstruction, roots, damaged line or broader sewer surcharge.
- Keep inspection footage, reports, invoices and before/after documentation together.
- For prevention work such as backwater valves, consult the applicable municipal rules and the properly qualified trade identified by the City of Montréal.