Water accumulation, infiltration and sewer backup

Learn more about the actions taken by the City of Laval in the event of water accumulation, infiltration or sewer backup, and what to do about it.

A network to monitor and maintain

There are more than 7,000 km of pipes beneath the streets of Laval, including water lines as well as sanitary and storm sewers.

The City of Laval regularly monitors the state of these underground infrastructures to identify priority actions and keep the network in good condition.

Water accumulation

Not to be confused with flooding events, which are major emergencies that can make roads impassable. Nevertheless, water accumulation can make travel difficult, particularly if you’re getting around on foot or by bicycle, or if you have limited mobility.

Blocked storm sewer main
Illegally backfilled ditch
Congested sump in winter
Slope preventing proper stormwater drainage on a street
Non-existent drainage system (storm sewer or ditch)
Main with insufficient capacity
Overloaded network

Climate change, by increasing the probability of heavy rains and extreme weather events, makes water accumulation problems more frequent.

Responsibility of the City of Laval

Build a storm sewer:
Homeowners and the City of Laval share the construction costs.
Digging a ditch:
This solution is adapted to non-urbanized areas, where the road is not bordered by a sidewalk or a curb.
Replacing one or more lines or adding lines to increase the network’s capacity and improve stormwater management.

Responsibility of the City of Laval

Protecting wetlands:
They absorb and naturally filter stormwater.
Installing drainage systems along streets, retention basins, etc.:
These infrastructures reduce the pressure on the underground network and improve the quality of the water discharged into the environment.

Responsibility of the owner

Ensure that rainwater gutters discharge water onto a permeable surface, such as a lawn. Learn more about disconnecting rainwater gutters.
Do not backfill ditches and waterways.
Please view Bylaw L-11870.

Water infiltration

Water infiltration occurs when water enters a building from the outside.

Poor watertightness of the building foundation, the windows or a garage door.
Poor stormwater drainage on the property around a house.
Presence of a water table close to the surface of the ground.

Responsibility of the City of Laval

Conduct the studies required to propose a solution if the infiltration is caused by inadequate water drainage on a public road or by a water or storm sewer line in poor condition.

Responsibility of the owner

Ensure that the foundation is watertight or correct stormwater runoff around the building.

Responsibility of the owner

Check the rainwater gutters on your house: Rainwater must be discharged at least one metre from the building so as not to damage the foundations. View Bylaw L-11870.

Ensure that mounding prevents water from accumulating close to the basement or garage, if your driveway slopes toward the house.
For further details, please view Article 4.01.03 of Bylaw L-11870.

Sewer backup

When rain or wastewater is not discharged toward the public network, it can lead to a backflow (backup) through your plumbing installations, including the toilets, sinks and floor drains, or on your property.

Blockage of the discharge pipe or discharge pipe not large enough.
Buildings at risk:
- Homes located in flood zones, where the sewer network is more susceptible to overloading.
- Buildings constructed at a lower elevation than the piped sewage systems. This is rare.

If you experience a backup problem, the first thing to do is call an RBQ-licenced plumber and CMMTQ member.

The plumber must:

Identify the source of the backup.
Locate and check the condition of the plumbing system in your basement.
Unclog the sewer line clean-out (PDF, 159 ko) in your basement. If you don’t have one, the plumber will have to install one.
Try to unclog the service line through the clean-out.
Depending on the nature of the backup, determine whether the responsibility lies with the City of Laval or the homeowner.
Provide you with a detailed invoice for the work completed.

If the plumber determines that the City of Laval must take action, complete the following steps:

1 – Contact 311. A service agent will transmit your request to the right department. Let the agent know that you are calling for a sewer backup following an expert assessment by a plumber. This will facilitate the process of assigning your case to the right team.

2 – The person assigned to your action request will contact you to schedule an appointment at your home, i.e., the location of the backup observed.

3 – To prove that a licenced plumber visited your house to carry out an inspection, you must show the plumber’s invoice to the person that contacts you. A simple photo taken with your cell phone or a digital photocopy will suffice.

4 – During the appointment, the City representative will ask you to sign a consent form to take action at your home.

To minimize the risk of a sewer backup, never pour into your plumbing system (sinks, toilets, etc.) cooking oil or waste that swells when in contact with water (e.g., diapers, sanitary napkins, makeup remover pads, disposable wipes, etc.), as these items could clog up a pipe.

This type of waste should never go into the toilet or sink (176 ko)

The City of Laval requires the installation of certain safety devices, including check valves, to prevent or minimize the damages. If the resident does not have these safety devices, theJossy City of Laval will not be held responsible for damages caused to a building or its contents.

According to municipal Bylaw L-11870, you must have, know the location of, and maintain the following equipment:

Check valves (193 ko)

Primary clean-out – planches 4 et 5

Secondary clean-outs – planches 4 et 5

Combined sewers (387 ko)

Double connections (438 ko)

Lifting pump (51 ko), also called a “sump pump”

Mounding above a down-sloping access way (82 ko), i.e., a sloping driveway

Service box (550 ko)