The short answer
Basement leak repair in Ontario ranges from about $400 for a small crack injection to $20,000–$30,000 for a full exterior waterproofing job with excavation. Most repairs fall somewhere in between, and the price is almost entirely determined by one thing: where the water is coming from.
A contractor who quotes you without looking at the outside of your house, checking the grading and downspouts, and walking the full perimeter is guessing. This guide explains what drives the cost so you can have a smarter conversation before you commit to anything.
What drives the cost of fixing a leaking basement
There are four main water paths into a basement. Each one has a different fix and a different price:
| Water source | Typical fix and cost range |
|---|---|
| Surface water — grading runs toward the house | Re-grade soil, extend downspouts: $500–$3,000 |
| Crack in poured concrete wall | Polyurethane injection from inside: $400–$800 per crack |
| Seepage through block or stone foundation | Interior drainage + sump: $5,000–$12,000 |
| Hydrostatic pressure — water table rising | Exterior waterproofing with excavation: $15,000–$30,000 |
| Failed weeping tile or blocked drain | Partial or full weeping tile replacement: $8,000–$20,000 |
Interior vs. exterior waterproofing: what is the difference?
Interior waterproofing — a drainage channel cut into the floor along the foundation perimeter, connected to a sump pump — does not stop water from entering the wall. It captures water that gets in and removes it before it causes damage. It is generally faster, less expensive ($5,000–$12,000 for a typical Ontario basement) and does not require excavation.
Exterior waterproofing applies a membrane to the outside of the foundation wall after excavation. It stops water at the source. It costs more ($15,000–$30,000) and takes longer, but it is the right solution when the foundation wall itself is failing, when interior drainage has already been tried and is not holding, or when there is structural cracking that needs to be addressed.
A contractor who only does one of these will usually recommend that one. Get a diagnosis from someone who offers both.
Grey-Simcoe specific
In the Collingwood, Wasaga Beach and Owen Sound area, the most common cause of spring flooding is grading that has settled over 10–20 years so that water now runs toward the house instead of away from it. This is a $500–$2,000 fix — not a $20,000 waterproofing job. We check this first.
Crack injection: when it works and when it does not
Polyurethane or epoxy injection fills a crack in a poured concrete wall from the inside. It works well for a single crack that is not actively moving. Cost: $400–$800 per crack for a licensed contractor.
It does not work for: block or stone foundations (which leak at the mortar joints, not a single crack), cracks caused by ongoing movement or settlement, or a wall that is seeping across the full face. In those cases, injection is a short-term fix that delays a larger problem.
How much does a sump pump installation cost in Ontario?
A basic sump pump installation — pit, pump, discharge line — runs $800–$2,000 depending on the depth and access. A battery backup adds $300–$600. A backwater valve (which prevents sewer backup during heavy rain, not just groundwater) adds $800–$1,500 and is sometimes required under Ontario Building Code for new work.
A sump pump alone does not fix a wet basement. It manages water that is already getting in. The pump is a symptom manager — useful, but not a substitute for addressing the water path.
What a legitimate quote includes
A proper basement leak repair quote should tell you: what the water source is and how it was identified, what the proposed fix addresses (and what it does not), which permits are required and who pulls them, and the warranty on the work.
A quote that does not name the water source is a guess. A quote that does not mention permits may be skipping ones that are required — which creates problems when you sell the house.
Getting an honest quote for your basement
We inspect the water path before we quote. You get a written, line-item scope — not a single number with no explanation behind it. Free on-site assessment, no obligation.