Drainage is the least glamorous money you will ever spend on a property and by a wide margin the most important. Water against a foundation is the one landscaping problem that turns into a structural problem, and every other thing you build in the yard is at risk until it is solved. It is also the area where the right fix and the wrong fix cost about the same.
Quick price summary
| Solution | 2026 cost | Best for |
|---|---|---|
| Downspout extension, buried to daylight | $380 – $1,300 | Water pooling at the foundation corners |
| Regrading, positive slope away from house | $1,600 – $6,500 | Ground sloping back toward the building |
| Swale (shallow graded channel) | $1,400 – $5,200 | Moving surface water across a lot |
| French drain, per linear foot | $65 – $135 | Saturated soil, a persistent wet zone |
| French drain, typical 40 ft run | $2,600 – $5,400 | Along one side of a house |
| Catch basin plus connection | $850 – $2,400 | A low spot that ponds after rain |
| Dry well / soakaway | $1,900 – $5,800 | Nowhere to daylight the water to |
| Sump pump, pit and discharge line | $1,900 – $4,800 | Water below grade, high water table |
| Window well drain | $900 – $2,500 | Basement window wells filling |
| Exterior weeping tile replacement | $180 – $380 per linear foot | Failed foundation drainage, major work |
| Permeable paver conversion, per sqft | $28 – $48 | Hard surface causing the runoff |
| Rain garden / bioswale | $2,200 – $8,500 | Managing volume attractively on site |
| Lot grading plan by an OLS or engineer | $650 – $1,900 | Required by some municipal approvals |
| Full lot drainage, combined solutions | $6,000 – $26,000 | Properties with several failure points |
Diagnose before you buy
The most expensive drainage mistake is installing the wrong fix competently. A French drain will not solve a grading problem, and regrading will not solve a high water table. Match the symptom to the cause:
- Water pools within 2 m of the foundation after rain, then drains in a day. Almost always grading, or downspouts discharging at the wall. Cheapest fix, biggest consequence if ignored.
- One low area holds water for two or three days. A catch basin tied to a discharge, or regrading if there is somewhere for the water to go.
- A broad area is spongy for a week after rain. Saturated soil, typically heavy clay. This is what a French drain is actually for.
- Water appears in the basement at the floor-wall joint. Below-grade water. Interior sump system or exterior weeping tile, and this is the expensive category.
- Water runs off the neighbour’s property onto yours. A swale or an interceptor drain along the property line, and a conversation with your neighbour before you build anything.
- It only happens in a heavy storm, then clears. Volume, not drainage failure. Consider a dry well or permeable surfaces rather than a drain.
A site assessment from a contractor should be free. If a contractor proposes a solution without watching where the water actually goes, or without a hose test, get a second opinion.
The rule that surprises people: you cannot send it next door
Ontario law and municipal by-laws both apply here, and homeowners regularly get this wrong.
Under Ontario common law you are generally entitled to let water flow naturally, but you are not entitled to collect, concentrate and discharge water onto a neighbouring property. A French drain that outlets at the property line, or a downspout piped to the fence, is the classic example. This is one of the most common neighbour disputes in this region and the remedy can include being ordered to undo the work.
On top of that, Hamilton, Burlington and Oakville all operate lot grading requirements. In broad terms:
- Established drainage patterns must be maintained. You cannot regrade in a way that redirects water onto an adjacent lot.
- New builds and many additions require an approved lot grading plan, with a deposit released only after a final grade inspection.
- Connecting private drainage into the municipal storm system requires approval, and in many cases is simply not permitted for residential yard drainage.
- Work near a watercourse, a ravine or Escarpment land may also fall under a conservation authority permit, which matters across a lot of Hamilton, Dundas and Ancaster.
Rules and thresholds change, so confirm with your municipality before work starts. The safe design principle is straightforward: manage the water on your own property, whether by daylighting it to a lower point you own, into a dry well, or into a rain garden.
What a French drain actually is, and when it is oversold
A correctly built French drain is a trench, typically 450 to 900 mm deep, lined with non-woven geotextile, holding a perforated pipe laid to a consistent fall of at least 1%, surrounded by clear washed stone, with the fabric wrapped over the top before backfill.
The parts that get skipped and the reasons they matter: the geotextile, without which fine clay silts into the stone and the drain is dead in five years; the washed clear stone rather than crusher run, which packs and stops draining; consistent fall, because a drain with a dip holds water rather than moving it; and a real outlet, because a drain that ends nowhere is a buried bathtub.
Where French drains are oversold: they are frequently proposed for problems that are really grading problems, because a drain is a bigger invoice than moving soil. If the ground slopes toward your house, fixing the slope is both cheaper and more effective. The ideal is a minimum fall of about 150 mm over the first 3 m away from the foundation.
Cost drivers
- Access. If a mini excavator can reach the work, cost stays low. Hand digging a 40 ft trench through a 36 inch gate can double the labour.
- Soil. Hamilton-area clay is slow to dig and heavy to haul. Rock or fill with buried rubble is worse.
- Depth. Cost rises sharply below about 900 mm because the trench needs shoring.
- Reinstatement. The trench crosses a lawn, that is sod. It crosses a patio, that is lifting and relaying pavers. It crosses a driveway, that is boring or cutting.
- Existing services. Locates are mandatory and free, but working carefully around gas, hydro and irrigation lines takes time.
- Disposal. Excavated clay has to go somewhere, typically $350 to $900 per truckload.
- Trees. Trenching through a mature root zone needs hand digging or an air spade to avoid killing the tree, which adds real cost.
Where drainage sits in the project order
Before everything. Drainage is the one item that must be resolved before any hardscape goes in, because every fix afterwards costs several times more. Discovering that water runs at the house after a $22,000 patio has been laid over the problem means lifting the patio to correct the grade.
If you are planning a multi-phase yard, put grading and drainage in phase one even if it means delaying the visible work by a season. It is also the one category where the cheapest competent fix is often the right one: a $600 buried downspout extension solves a surprising share of the wet-yard complaints we get called about.
Frequently asked questions
How much does a French drain cost in Ontario?
$65 to $135 per linear foot in 2026, so a typical 40 ft run along one side of a house costs about $2,600 to $5,400. Cost rises with depth, hard access, clay soil and reinstating any hard surfaces the trench crosses.
How much does it cost to regrade a yard?
$1,600 to $6,500 for a typical residential regrade to establish positive drainage away from the house. Larger lots, significant fill import or full lot regrading with an engineered plan can run well past $10,000.
Can I drain water onto my neighbour’s property?
No. You may not collect, concentrate and discharge water onto adjacent land, and municipal lot grading rules also require established drainage patterns to be maintained. Manage the water on your own property, by daylighting it to a lower point you own, a dry well or a rain garden.
Do I need a permit for yard drainage work?
Often yes, depending on scope. Lot grading approval is commonly required for new builds and substantial regrading, connecting to municipal storm infrastructure needs approval, and work near a ravine, watercourse or Escarpment land may need a conservation authority permit. Confirm locally before starting.
What is the cheapest way to fix a wet yard?
Burying downspout extensions to discharge well away from the house, at $380 to $1,300. It solves a large share of pooling complaints and should always be ruled out before anyone quotes you a French drain.
Will a French drain fix water in my basement?
Sometimes, if the water is surface water reaching the foundation. Water entering at the floor-wall joint is below-grade water and usually needs an interior sump system or exterior weeping tile replacement, which is a much larger job at $180 to $380 per linear foot.
How long does a French drain last?
Twenty to forty years when built with non-woven geotextile, clear washed stone and a real outlet. Built without the fabric in clay soil, it can silt up and stop working within five.
Should drainage be fixed before I build a patio?
Always. Correcting grade after a patio is laid means lifting the patio. Drainage belongs in phase one of any yard project, even if it delays the visible work by a season.