Rainwater and flood zones in Vaudreuil-Dorion
Updated September 28, 2026
In Vaudreuil-Dorion, rainwater does not take the same path everywhere. Depending on the age of the neighbourhood, the street is served by a combined sewer (a single pipe, before about 1960), by a pseudo-separate system or by a newer separate system. Some roads are also lined with ditches, with culverts under the driveways, and the city forbids owners to fill these ditches in.
On August 9, 2024, the remnants of Debby made several streets impassable and reached homes in several parts of the city, through surface water as well as sewer backup. The city requires a backwater valve in every home, whatever its age, and offers a free inspection to eligible owners whose homes were hit.
Heavy rain events
What public sources report about heavy rain in Vaudreuil-Dorion, at sector level.
Remnants of Debby: the city reports 219 mm of rain in 20 hours, several impassable streets, one street that subsided and a landslide. Water entered homes through surface runoff and through sewer backup; the city had both mechanisms explained at a presentation for residents on November 21, 2024. Earlier, at the September 3 council meeting, the then-mayor had said that backups were more frequent in some parts of the city and that some neighbourhoods had flooded because of power outages that evening.
Sources: Ville de Vaudreuil-Dorion, Mesures d'urgence · Ville de Vaudreuil-Dorion, présentation citoyenne du 21 novembre 2024 · Néomédia Vaudreuil-Soulanges, 4 septembre 2024
Good to know in Vaudreuil-Dorion
- The city's technical presentation of November 21, 2024 distinguishes three systems by period: combined before about 1960, pseudo-separate until about 1976, then separate. The first household weak spot it lists is the reverse-slope garage driveway, where street water collects and comes in through the garage door. (Ville de Vaudreuil-Dorion, présentation citoyenne du 21 novembre 2024)
- By-law 1797: no one may close a public or private roadside ditch, except as part of a municipal project. Installing, lengthening or repairing a culvert requires a certificate of authorization, and the city chooses the pipe diameter. (Ville de Vaudreuil-Dorion, règlement 1797 sur les fossés et ponceaux)
- By-law 1744, art. 12: gutter water must be released at the surface at least 1.5 m from the building, on the lot, never into the street or onto a hard surface. A reverse-slope driveway must drain by gravity to the storm sewer or to a sump pit. (Ville de Vaudreuil-Dorion, règlement 1744 sur la gestion des eaux pluviales)
- The city requires a backwater valve in every home, whatever the year of construction, on the branches that serve basement fixtures such as floor drains. The valve must stay easy to reach for maintenance and cleaning. (Ville de Vaudreuil-Dorion, Alimentation en eau et réseau d'égouts)
- Zoning by-law 1872, art. 6.19: a basement garage, with its access below the level of the street, is prohibited for single-family, two-family and three-family dwellings. The rule applies to new construction: an older house may have one. (Ville de Vaudreuil-Dorion, règlement de zonage no 1872)
- Subsidized inspection and support program (by-law 1866): the eligible owner of a building hit by sewer backup or water infiltration since January 1, 2023 can get an inspection, a diagnosis and a specification of corrective work free of charge. The program does not pay for the work. (Ville de Vaudreuil-Dorion, Programme d'inspection et d'accompagnement subventionné)
Rivers and lakes: what the check does not cover
Waterways in Vaudreuil-Dorion: Lake of Two Mountains, Vaudreuil Bay and Quinchien River.
In May 2017, high water on Lake of Two Mountains flooded streets and cut off part of avenue Saint-Charles. On April 27, 2019, the mayor declared a local state of emergency because of flooding and a forecast rise of the Ottawa River. In 2023 and 2026, the city installed dikes on avenue Saint-Charles and set up pumps, notably in Vieux-Dorion.
Zoning by-law 1872 defines the floodplain by 20-year and 100-year flood elevations. Québec postponed the new lake maps due on August 1, 2026; they were still unpublished on September 15.
Sources: Infosuroit, 6 mai 2017 · Infosuroit, 27 avril 2019 · Infosuroit, 2 mai 2023 · Néomédia Vaudreuil-Soulanges, 24 avril 2026 · Ville de Vaudreuil-Dorion, règlement de zonage no 1872 · Communauté métropolitaine de Montréal, communiqué du 30 juillet 2026 · La Presse, 15 septembre 2026
The check is about the rain that falls on the area and runs off over the ground. River and lake flooding is not part of it: in the simulation, a nearby river or lake holds no water. For a waterfront property, the official map comes first.
What we know about the ground in Vaudreuil-Dorion
These values come from the public sources the check uses. They describe the area, not an address.
| 1 m terrain model (NRCan HRDEM) | Available across the whole area |
|---|---|
| Nearest rainfall gauge (ECCC) | Oka, 11 km awayLocal rainfall statistics. |
| Municipal street drains | Not modelled: with no open municipal inventory, the check's depths are an upper bound wherever a working network would carry water away |
| Mapped culverted road crossings | 251Culvert lines mapped in OpenStreetMap (ODbL). |
Data Source: Environment and Climate Change Canada, Short Duration Rainfall Intensity-Duration-Frequency Data, used under the ECCC Data Servers End-use Licence.
Area analysed: adapted from Statistics Canada, Census Subdivision Boundary File (cartographic), 2021 Census. This does not constitute an endorsement by Statistics Canada of this product.
Probed on September 28, 2026.
The official map and what it does not show
Québec's flood-zone maps cover rivers and lakes. They do not show rain water collecting on a lot, in a low spot or at the bottom of a sloping driveway. Check the official map for the address first: it is what says whether a property is in a flood zone.
FloodVerity does not reproduce these maps and does not state any regulatory zone.
Check an address in Vaudreuil-Dorion for $39
We drop a 100-year, one-hour design storm on the ground around the property, route the runoff, and email you the peak depth of rain water at the address, where it collects, a map and a 3D view.
What the check does not do
- This check models rain falling on the area itself and running off over the terrain. Water arriving from a river or lake, sewer backup, ice jams and storm surge are not modelled.
- The pipe network itself, roof and lot drainage, and sewer backup are not modelled.
- Where the structures inventory records a culverted road crossing, it is lowered to a partly blocked opening rather than solved hydraulically.
- It does not replay the storms described on this page: it applies a 100-year, one-hour design storm.
- It is a screening: a simulated storm on public terrain data, not a hydraulic study, not an official flood-zone determination, not an insurance opinion.
Notaries and brokers in Vaudreuil-Dorion
We run the same check over a list of addresses and deliver a spreadsheet ranking them by the modelled rain depth. Priced per address, on quote.
Email [email protected]Other towns and areas
The FloodVerity check is a screening: it applies a design rainstorm to public terrain data and simulates where the rain runs and collects. It is not a hydraulic study or an official flood-zone determination, and it covers neither river and lake flooding nor sewer backup.