A window well fills with water because the drain at the bottom of the well is blocked, missing, or never connected to anything that carries water away, and once that drain stops working, rain, snowmelt and groundwater collect faster than they can escape, rise up the well wall, and find the cold joint where the well meets your foundation. That joint is not waterproof. Water sitting against it for a few days is usually all it takes to show up as dampness or a stain on your basement wall.
The drain is the whole system, and it's almost always the problem
A properly built window well has a 3- to 4-inch drain at the base. In most GTA homes it's either a PVC pipe tied into the weeping tile around your footing, or a gravel-filled dry well that lets water percolate into the surrounding soil. Both work. Both also fail on a predictable timeline.
Silt, clay particles, roof grit, sand from deteriorating well walls and 15 years of leaves wash into that drain and cap it. Toronto's clay-heavy soil makes this worse than in most Canadian cities: fine clay particles suspend in runoff and settle into the pipe like mortar. Once the top inch of gravel or the first foot of pipe is sealed, the drain is effectively gone.
You can usually confirm it yourself. After a heavy rain, look down the well:
- Water pooling at the bottom and staying for more than 24 hours
- A fan of silt or grit spread out from the drain
- A water line staining the well wall a few inches up
- Water that drains slowly over two or three days instead of hours
If you see any of those, the drain is the first thing to test, pour a bucket of water down it and watch. If it backs up, you've found your answer.
The other causes, in rough order of how often we see them
Grading that slopes toward the well
The Ontario Building Code expects ground to fall away from the foundation, the long-standing rule of thumb is about 6 inches of drop over the first 10 feet. Backfill around a foundation settles for the first five to ten years after a house is built, and a window well is a hole in that backfill. Soil slumps toward it. A well surrounded by ground sloping inward is a funnel, and no drain will keep up with a funnel.
A failed seal at the foundation wall
The joint where the window well wall meets your foundation is a cold joint between two separate pours or between concrete and masonry. It was sealed with a membrane or sealant when it went in. That seal has a realistic service life of 10 to 15 years. When it lets go, water doesn't need to fill the well, it just needs to sit against that seam.
Cracks and porous well walls
Corrugated metal wells rust through at the base, usually right at the soil line. Poured concrete wells crack at corners and along the cold joints. Block wells wick water through the mortar. Any of these lets groundwater in through the wall itself rather than over the top.
Downspouts and sump discharge
A downspout discharging two feet from a window well dumps hundreds of litres into that spot during a single storm. Same for a sump pump line that terminates against the foundation. This is the cheapest problem on the list to fix and one of the most common.
High or perched water tables
Parts of Toronto sit on clay till that holds water rather than draining it. During spring melt or after a week of rain, the water table can rise above the base of your window well. A dry well design simply cannot work in saturated clay, it needs to be piped to a positive drain instead.
No cover, or a cover that channels water in
A window well cover should shed water away from the well. A flat or poorly pitched cover, or a cover that's cracked at the edges, does the opposite. Clear polycarbonate covers also need to be cleared of snow load in February, or the meltwater goes straight down the well when it finally gives.
Water coming from above the well
If the damp patch is at the top of the window rather than the bottom, the well may not be the source at all. Failed masonry above the opening, deteriorated mortar, or a corroded steel lintel carrying the brick over the window can all let water in at the head of the opening. A lintel that has rusted and expanded will crack the masonry around it, that's a structural repair, not a drainage one, and it needs to be identified before anyone starts digging.
Why this happens so often in Toronto
Three local conditions do most of the damage. First, clay soil: it drains slowly, holds water against foundations, and silts up drains fast. Second, freeze-thaw: Toronto gets roughly 40 to 50 freeze-thaw cycles a year, and every one of them works on the seal at the base of a window well. Water gets into a hairline crack, freezes, expands, and widens it. Third, the housing stock: the postwar bungalows across Etobicoke, Scarborough and North York were built with shallow window wells that were never designed for the runoff volumes that come off modern roofs and driveways, especially where a neighbouring lot has been severed and infilled.
What it costs to fix in Toronto
Every one of these numbers is a typical range, and the final cost varies a lot depending on job size, scope and site conditions, access, depth of the well, whether the footing drain is reachable, and how much soil excavation is needed all move the number.
- Window well drainage and waterproofing: $500–$3,000. Final cost varies with job size, scope and site conditions.
- Window well leak repair: $500–$2,000. Final cost varies with job size, scope and site conditions.
- Window well replacement or repair: $500–$2,000. Final cost varies with job size, scope and site conditions.
- Window well raising: $800–$1,800. Final cost varies with job size, scope and site conditions.
- Window well covers: $300–$900. Final cost varies with job size, scope and site conditions.
- New window well installation: $800–$2,500. Final cost varies with job size, scope and site conditions.
- Basement waterproofing: from $1,200. Final cost varies with job size, scope and site conditions.
- Egress window installation: $4,500–$8,000. Final cost varies with job size, scope and site conditions.
If the well is being replaced or raised, the work may touch your egress path. Any window well serving a basement sleeping room has to keep the window meeting OBC 9.9.10.1 exit sizing, minimum opening area, maximum sill height, and a clear well large enough to climb out of. Raising a well or changing its dimensions can trigger a building permit through Toronto Building, and inspection is easier to arrange before the excavation is backfilled than after.
How we diagnose and fix a wet well
We start with a free site evaluation, usually within 48 hours of your call. On site we:
1. Water-test the existing drain to confirm whether it's flowing, slow, or dead
2. Check grading and downspout discharge within a 10-foot radius of the well
3. Inspect the well-to-foundation joint and the well walls for cracks, rust-through and failed sealant
4. Check the masonry and lintel above the opening if the leak is high on the wall
5. Confirm the window still meets exit sizing if the well is going to be altered
From there the fix is one of four things: clear and re-line the drain and tie it to a positive outlet, rebuild the well with proper drainage and a waterproofed joint, raise the well and regrade around it, or address the water before it arrives by extending downspouts and correcting the slope. Soil excavation is kept as tight to the well as the repair allows, and we backfill and compact in lifts so the ground doesn't settle back into a funnel next spring.
We install year-round. Winter work in Toronto means managing frozen ground and protecting the excavation, but a leaking well doesn't wait for May, and neither should the repair.
Why homeowners call us
We're a family-run Toronto basement contractor with 12 years of below-grade work and more than 400 egress windows and window wells installed across the GTA. Every egress installation is built to OBC 9.9.10.1, we're licensed, insured and WSIB covered, and every install carries a 10-year workmanship warranty. We don't sell a cover when the drain is the problem, and we don't quote a waterproofing job when a $40 downspout extension will solve it.
Get a free quote
If your window well is holding water, send us a photo and we'll book a free site evaluation, you'll have a written quote within 48 hours, with the drainage design and the price broken out so you can see exactly what you're paying for. Call Egress Window Pros Toronto or use the contact form on this page.