London Basement Flood Planning Checker
Enter the first three characters of your postal code to find the most relevant local planning guide. This tool does not calculate parcel flood risk or determine City grant eligibility.
Find Your Planning Path
Your forward sortation area (FSA) is used only to route you to broad neighborhood context and better next questions.
Home History
In an older home, ask how the foundation drains and sanitary line are connected. Confirm the actual setup through inspection rather than inferring it from the postal code.
Lot & Drainage
Reverse-grade driveways, low points, discharge locations, and neighboring grades are property-specific. They need an on-site assessment.
Grant Eligibility
A postal code and construction year do not establish eligibility. Property type, proposed work, application timing, estimates, permits, and written City approval matter.
What To Do With Your Result
If sewer backup is the concern, review backwater valve costs. If groundwater is the concern, compare the sump pump grant path, then check eligibility requirements.
Want the full grant checklist?
Before you hire a contractor or cut concrete, make sure your quote, permit path, and application order are correct.
Download the Free Grant GuideWhat a Postal Area Can—and Cannot—Tell You
A three-character postal area covers many streets, building ages, lot grades, drainage systems, and elevations. It can help organize local content, but it cannot establish a home's flood probability, identify the source of past water, or predict City grant approval.
For authoritative flood-hazard mapping, use City or conservation-authority mapping and property-specific advice. For basement prevention planning, start with where the water entered, what it looked like, and how the home drains.
1. Historic Infrastructure (N6B, N6C)
Areas: Old South, Wortley Village, Woodfield, Hamilton Road.
Planning questions: What is the home's actual construction year? Do foundation drains connect to the sanitary sewer? Has water appeared at a drain, wall-floor joint, or both? A plumber or drainage professional may need to verify the setup. See the Old South guide and backwater valve cost guide.
2. Hilly Terrain & Reverse Grades (N6K)
Areas: Byron, Oakridge, Westmount.
Planning questions: Is the driveway reverse-graded? Where can sump discharge go without creating a nuisance or violating drainage rules? Our Byron and Oakridge guide and sump discharge guide explain what to inspect.
3. Newer Subdivisions (N5X, N6G)
Areas: Masonville, Hyde Park, Sunningdale.
Planning questions: Does the home have a sump, where does it discharge, how old is the pump, and what happens during a power outage? The current grant page limits battery-backup funding to a unit installed with a new sump pump. Review the Masonville and North London guide.
📍 The bottom line: Treat this as content routing, not a risk score. Use the symptom diagnostic, then confirm scope and eligibility before work starts. Method and claims reviewed July 22, 2026.
Primary public sources
City of London flooding information, Basement Flooding Grant Program, and Drainage By-law WM-4.