French Drain Installation Cost
The french drain installation cost in 2026 averages $20–$50 per linear foot for exterior drains and $40–$100 per foot for interior (basement) drains, putting most residential projects between $2,000 and $12,000. If your yard turns into a swamp every rainstorm or your basement weeps water through the walls, this guide breaks down exactly what you will pay and why.
What Is a French Drain?
Despite the name, the french drain has nothing to do with France — it is named for Henry French, the 19th-century Massachusetts farmer who popularized it. A french drain is a gravel-filled trench containing a perforated pipe that collects groundwater and redirects it away from where you do not want it: foundations, basements, soggy yards, and retaining walls.
Water flows into the trench through the gravel, enters the pipe through its perforations, and travels downhill (gravity does the work — these systems need proper slope, typically 1% grade or about 1 inch of fall per 8 feet) to a discharge point: daylight (a downhill outlet), a dry well, a storm drain (where legal), or a sump pump basin.
French drains solve groundwater problems — water moving through soil toward your foundation. They do not fix roof runoff problems (that is what gutters and downspout extensions are for) or plumbing leaks (see our leak detection guides if your "water problem" might be a pipe). Diagnose correctly before digging: extending downspouts 10 feet from the house ($15 in parts) fixes a surprising number of "basement leaks."
Cost Per Linear Foot
| Drain type | Cost per linear foot | What it includes |
|---|---|---|
| Exterior shallow (curtain drain) | $20 – $35 | 12–18 in. deep trench, pipe, gravel, fabric |
| Exterior deep (foundation footing) | $35 – $55 | 4–6 ft deep, excavation, waterproofing tie-in |
| Interior basement perimeter | $40 – $100 | Concrete cutting, trench, pipe, sump basin, re-pour |
| Retaining wall drain | $25 – $45 | Behind-wall drainage with outlet |
| Dry well (discharge point) | $500 – $2,000 | Buried pit, per unit installed |
Per-foot pricing assumes reasonable access and soil. Rocky soil, buried utilities, tree roots, and deep footings push costs toward the top of every range — sometimes past it.
Exterior vs Interior French Drains
These are fundamentally different projects solving the same problem from opposite sides of the foundation wall.
| Exterior french drain | Interior french drain | |
|---|---|---|
| Where | Around the outside of the foundation | Around the inside basement perimeter |
| How it works | Intercepts water before it reaches the wall | Collects water that enters and pumps it out |
| Typical cost | $2,000 – $6,000 | $5,000 – $12,000 |
| Disruption | Landscaping torn up; exterior digging | Basement floor cut; concrete dust |
| Needs sump pump? | Only if no downhill outlet | Almost always (adds $500 – $1,500) |
| Best for | Yard drainage, new waterproofing, accessible exterior | Finished basements, high water table, no exterior access |
Exterior is the better engineering solution — it keeps water off the foundation entirely — but it requires digging up landscaping, patios, or driveways, which is why interior systems are so common in finished homes. If your basement is unfinished and the exterior is accessible, exterior usually wins on both cost and performance.
Total Project Cost Ranges
| Project | Typical total |
|---|---|
| Yard curtain drain (100 ft) | $2,000 – $3,500 |
| Foundation perimeter, exterior (150 ft) | $5,000 – $8,000 |
| Basement interior perimeter + sump pump | $6,000 – $12,000 |
| Retaining wall drainage (50 ft wall) | $1,500 – $2,500 |
| Full system: exterior drain + sump + discharge | $8,000 – $15,000 |
What Affects the Price
- Depth and length: deeper and longer trenches mean more excavation — the dominant cost.
- Soil and rock: clay is slow to dig; rock requires equipment or blasting and can double excavation cost.
- Access: a mini-excavator needs a gate or path. Tight urban lots mean hand digging at premium labor rates.
- Concrete cutting (interior): cutting the basement slab runs $5–$12 per linear foot before the drain itself.
- Discharge solution: daylight outlet is cheapest; a dry well adds $500–$2,000; a sump pump system adds $500–$1,500 plus electrical.
- Landscaping restoration: sod, irrigation repair, and regrading are often separate line items — clarify in the quote.
- Permits: $50–$300 in most jurisdictions; required where the drain ties into storm systems.
- Region: labor rates vary widely — see our plumber hourly rate guide for regional context (drainage contractors track similarly).
DIY vs Hiring a Pro
A shallow yard curtain drain is one of the more DIY-feasible drainage projects: rent a trencher ($150–$300/day), buy perforated pipe, gravel, and filter fabric, and a handy homeowner can do 50–100 feet in a weekend for $500–$1,500 in materials. The critical skills are maintaining slope and choosing a real discharge point — a drain to nowhere is just an expensive hole.
Hire a pro for: deep foundation drains (excavation safety, waterproofing tie-in), interior basement systems (concrete cutting, structural concerns), anything near utilities (call 811 before you dig — it is free and legally required), and any project where getting it wrong means water in the house. A failed DIY drain costs more to fix than the pro would have charged.
Materials matter less than installation: use perforated PVC or corrugated HDPE pipe (4-inch is standard residential), surround it with washed gravel (not crushed limestone dust, which clogs), wrap the trench in filter fabric to keep silt out, and maintain fall to daylight or a sump. Skip the fabric and the system silts up in 5–10 years instead of lasting 30+.
Maintenance and Lifespan
A properly built french drain lasts 30–50 years with only minimal routine maintenance each year. Keep the discharge outlet clear of leaves and debris, verify water actually exits during heavy rain (walk the outlet in a storm — it takes two minutes), and flush the cleanouts annually if your system has them. In cold climates, also confirm the outlet does not freeze shut in winter, since a frozen outlet can back the entire system up. If flow slows after a decade, a plumber can jet the line ($200–$400) before assuming replacement.
Warning signs of failure: water returning to the old problem areas, soggy spots directly over the drain line (suggesting a crushed or clogged section), and sump pumps running constantly in dry weather (suggesting a plumbing leak, not groundwater — get that checked separately).
When a french drain is NOT the answer: be wary of any contractor who prescribes a $10,000 interior system before ruling out simpler causes. Water stains on a basement wall directly below a downspout usually mean the gutter is overflowing or the downspout discharges at the foundation — a $30 extension fixes it. Efflorescence (white mineral crust) with no active wetness is often historic moisture, not an ongoing leak. And water appearing only during heavy rain near window wells points to clogged well drains, not a high water table. A trustworthy drainage contractor investigates the water's source first and proposes the smallest effective fix; anyone who skips straight to the most expensive option is selling, not diagnosing.
Dealing with water where it should not be? Call (877) 762-1902 — Emergency Plumbing Services diagnoses drainage and water intrusion problems in 11,114 cities nationwide, and will tell you honestly whether you need a drain, a sump pump, or just longer downspouts.