waterdamagequotesFlood maps · Edmonton
Edmonton flood maps: the river on the map, and the three kinds of flooding that are not
Most of Edmonton’s flood types are not the river. The North Saskatchewan runs through the middle of the city in a deep valley, and the provincial flood maps cover it. But EPCOR, the city’s drainage utility, names four kinds of flooding, and three of them happen on streets and in basements that no river map touches.
This page sets out those four kinds, what the provincial flood map covers and how Alberta defines it, what EPCOR’s $1.6-billion stormwater plan is doing about the rest, what a homeowner can check, and how insurance and the city’s programmes fit in. The backwater valve subsidy and the free inspection are on the Edmonton page.
The short version
- EPCOR names four types of flooding in Edmonton: overland, sewer surcharging, river and groundwater.
- Alberta’s flood maps are drawn to the 1:100 flood, split into floodway and flood fringe; they map the river, not the sewers.
- EPCOR’s Stormwater Integrated Resource Plan was presented as a 20-year, $1.6-billion plan.
- The City told the Province it supports updating the provincial flood map.
Four kinds of flooding
EPCOR Edmonton, Flood Mitigation · 2026
EPCOR's four: overland flooding, when rain falls faster than the ground or sewers can absorb it; sewer surcharging, when the stormwater system reaches capacity; river flooding, when flows in the North Saskatchewan River watershed rise beyond the banks; and groundwater flooding, when the water table rises in heavy rain. It says the stormwater system is designed for typical rainfall and that unusually intense or prolonged rain may temporarily exceed its capacity.
| Type | What causes it | Shown on a river flood map? |
|---|---|---|
| Overland | Rain falls faster than ground or sewers can absorb it | No |
| Sewer surcharging | The stormwater system reaches capacity | No |
| River | North Saskatchewan flows rise beyond the banks | Yes |
| Groundwater | The water table rises in heavy rain | No |
The table is the reason a homeowner in Edmonton can check a flood map, find their address outside every coloured zone, and still flood. Three of the four types are driven by how much rain falls in an hour and what the sewers and the ground can take, and they happen across the city, not along the river.
The river, and the provincial map
Government of Alberta, Flood Hazard Identification Program · 2026
The flood hazard area is the land flooded in that design flood, typically divided into the floodway — the highest hazard, where flows are deepest, fastest and most destructive — and the flood fringe, where water is shallower and slower. Alberta calls overland flow a legacy flood fringe sub-zone being phased out, points to its online Flood Awareness Map Application, and warns that flood maps are not available in all communities and flood risks exist in areas without mapping.
Alberta’s flood maps are drawn to that 1:100 standard and split the flooded area in two. The floodway carries the deepest, fastest water and is where development is most restricted; the flood fringe is shallower and slower. The Province publishes its final flood maps through its Flood Awareness Map application, and the City has said it supports an update:
City of Edmonton, Climate Adaptation Plan — Path 3 progress (June 2026) · 2026
Under the goal “Edmonton is a flood resilient community”, the City also lists bringing changing flood risk into municipal planning tools and developing a river flooding resilience programme.
EPCOR Edmonton, Flood Mitigation · 2026
EPCOR's water and power utilities are part of that centre, it says.
EPCOR’s own river work is about its water treatment plants. Its plan includes permanent flood barriers at the E.L. Smith and Rossdale plants — a reminder that the utility treats the river as a real, if rare, hazard.
Sewer surcharging: the flooding most homes get
EPCOR Edmonton, Flood Mitigation · 2026
EPCOR continues: water levels in the sewer network can then rise and increase the risk of basement flooding or sewer backups — the flooding a river map does not show.
When the storm sewers are full, water in the pipes rises, and the lowest openings connected to them are basement floor drains. That is why EPCOR’s programmes for homeowners are about backwater valves and lot grading rather than the river. Edmonton has required backwater valves in new homes since 1988 or 1989, depending on which official source you read:
City of Edmonton, The Homeowner’s Guide to Lot Grading and Drainage Issues (PDF) · 2020
Dated April 2020. EPCOR's own backwater valve page says instead that valves were “not required in homes built before 1989”, and its subsidy targets homes built before 1989. The two official sources differ by a year. For a house built in 1988 or 1989, check the house rather than the date.
Groundwater
EPCOR Edmonton, Flood Mitigation · 2026
EPCOR adds that efforts are under way to better understand groundwater in Alberta.
Groundwater flooding is the slow one: the water table rises after days of rain and water comes through the foundation or the floor. It is also the one insurance treats most cautiously, because seepage is a typical exclusion and groundwater cover is optional where it is sold — see ground water coverage.
What EPCOR is building
EPCOR Edmonton, Flood Mitigation — Stormwater Integrated Resource Plan (SIRP) · 2026
How EPCOR describes the SIRP as originally presented in 2018 and detailed in a May 2019 Utility Committee report. Its five approaches: SLOW (dry ponds, low impact development), MOVE (tunnels, trunks, separating combined sewers), SECURE (property flood-proofing, outfall gates, protecting the E.L. Smith and Rossdale water treatment plants), PREDICT (radar, sensors, an integrated operations centre) and RESPOND.
The plan’s five verbs map onto the four flood types. SLOW and MOVE are about overland flooding and sewer surcharging: dry ponds and rain gardens hold water back, larger tunnels and the separation of combined sewers carry more of it away. SECURE covers property flood-proofing and the river. PREDICT and RESPOND are the sensors, radar and emergency response. If your neighbourhood has a flood mitigation project under way, EPCOR lists it as a construction project.
What a homeowner can check
EPCOR Edmonton, Flood Mitigation · 2026
From EPCOR's property list, with: clean and repair eavestroughs and downspouts; maintain window wells; use rain barrels; clean debris from backwater valves; install a backwater valve; seal foundation cracks; and make sure the property slopes away from the house. It also points to the RainWise rebate for rain gardens and similar features.
EPCOR Edmonton, Flood Prevention Home Inspection · 2026
Between roughly April and October the inspection covers the whole property; between November and March it focuses on the interior, by EPCOR's account. None of the Ontario programmes this site has read describes a free inspection of this kind; Toronto's closest equivalent is a $500 subsidy towards a home plumbing assessment.
The free inspection is the useful first step, because it is done by someone who knows the local drainage and looks at grading, downspouts, the backwater valve and the sump in one visit. The sump pump maintenance and eavestrough pages cover two of EPCOR’s checklist items in detail.
Insurance, and who pays
EPCOR Edmonton, Sewer Lines · 2026
And the homeowner for sewer lines on the property, “including the backwater valve if one is present”. EPCOR also states that it will not reimburse plumber's fees regardless of where the blockage is located, though its drainage service guidelines waive service fees where a technical review finds the problem on the public portion.
Government of Alberta, Insurance and disasters · 2026
Alberta's government definition puts water seeping through basement cracks under overland flooding — the same route GIO and the Intact Centre describe as ground water. Two public bodies, one crack, two names. The same Alberta page states that sewer back-up insurance is generally considered readily and reasonably available in Alberta and that Albertans are expected to maintain it.
Alberta’s own definition of overland flooding includes water seeping through basement cracks, which insurers elsewhere call ground water. That mismatch is the reason to ask your broker which of the four EPCOR types your policy covers, by name. Sewer backup and overland water are both optional endorsements in Canada; river flooding falls under overland where it is sold.
Insurance Bureau of Canada, Water Damage and Flood Protection · 2026
IBC's wording is unambiguous: “Damage caused by the backing up of sewers and drains is typically not covered by a standard policy.” It adds that “optional sewer backup is offered by most insurers” — so the cover exists, it is just not switched on by default.
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Questions people actually ask
Where can I see a flood map for Edmonton?
Alberta publishes its final river flood maps through the provincial Flood Awareness Map application. They map the North Saskatchewan River to the 1:100 flood; they do not show sewer surcharging, overland or groundwater flooding.
What types of flooding happen in Edmonton?
EPCOR names four: overland flooding, sewer surcharging, river flooding and groundwater flooding.
Why did my basement flood if I'm not in a flood zone?
Most likely sewer surcharging or overland water. EPCOR says sewer surcharging happens when the stormwater system reaches capacity in heavy rain, raising water levels in the sewers and the risk of basement flooding or backups.
What is EPCOR doing about flooding?
EPCOR's Stormwater Integrated Resource Plan, presented as a 20-year, $1.6-billion plan, works to slow, move, secure, predict and respond to floodwater, with dry ponds, larger tunnels, sewer separation, flood-proofing and monitoring.
Is the Edmonton flood map being updated?
The City of Edmonton's June 2026 adaptation progress report lists feedback the City gave the Province supporting an update of the provincial flood map.
Does insurance cover flooding in Edmonton?
Only through optional endorsements: sewer backup for surcharging, and overland water for river and surface flooding where offered. Alberta's definition of overland flooding includes water seeping through basement cracks, so ask your broker how your wording treats each type.
Where to read next
- Edmonton’s $800 valve subsidy
- How to read any flood map
- Western DFA
- Overland water coverage
- Fraser Valley flood maps
Sources cited on this page
- EPCOR Edmonton, Flood Mitigation
- Government of Alberta, Flood Hazard Identification Program
- City of Edmonton, Climate Adaptation Plan — Path 3 progress (June 2026)
- City of Edmonton, The Homeowner’s Guide to Lot Grading and Drainage Issues (PDF)
- EPCOR Edmonton, Flood Mitigation — Stormwater Integrated Resource Plan (SIRP)
- EPCOR Edmonton, Flood Prevention Home Inspection
- EPCOR Edmonton, Sewer Lines
- Government of Alberta, Insurance and disasters
- Insurance Bureau of Canada, Water Damage and Flood Protection
Every figure above was read from the source it is attributed to on September 20, 2026. How we check this.
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