French Drain Cost Guide (2026): Installed Prices & DIY Savings

What a French Drain Costs in 2026

A French drain costs $10 to $50 per linear foot installed in 2026, depending on the type and depth. A simple exterior yard drain runs at the low end; an interior basement perimeter drain with a sump pump runs at the high end. As a DIY project, a straightforward exterior drain costs $8 to $20 per linear foot in materials.

For a typical 50-foot exterior drain, expect roughly $500 to $1,500 installed, or $400 to $1,000 DIY. A full interior basement system can run $5,000 to $12,000 because it involves breaking concrete, installing a perimeter channel, and adding a sump pump.

The name is a bit misleading — a French drain has nothing to do with France. It is simply a gravel-filled trench with a perforated pipe that collects water and carries it somewhere safe. The concept is the same whether it protects a lawn, a slope, or a foundation.

Before pricing, size your materials. Our Retaining Wall Drainage Calculator and Gravel Calculator tell you exactly how much drainage stone and perforated pipe your trench needs, so you can compare quotes against real numbers.

Cost by Type: Exterior, Curtain, Footing & Interior

Not all French drains are the same, and the type you need drives the price far more than the length. See the table above for a side-by-side comparison.

Exterior (yard) drains are the cheapest — a shallow trench that collects surface water from a soggy lawn or a low spot and routes it to daylight or a dry well. Most homeowners can DIY this one.

Curtain drains sit uphill of the area you want to protect and intercept water before it arrives. They are the go-to solution on a slope and pair naturally with retaining walls.

Footing (foundation) drains run alongside the foundation footing on the exterior and carry water away before it seeps through the wall. Interior drains are installed inside the basement perimeter, usually with a sump pump, when exterior work is not practical. These two are the most expensive because of excavation depth or concrete cutting.

Signs You Actually Need a French Drain

A French drain is the right fix for a specific problem: water collecting where it should not. It is not a cure-all, so match the solution to the symptom.

You likely need one if: your yard stays soggy or has standing water days after rain; water runs down a slope toward your house; your basement or crawlspace gets damp or floods; or a retaining wall is showing signs of water pressure (bulging, leaning, efflorescence).

You may not need one if the real problem is grading. Sometimes water pools simply because the ground slopes toward the house. Re-grading the soil to fall away from the foundation at 6 inches over the first 10 feet is cheaper than a drain and should always be the first step.

Gutters and downspouts matter too. A shocking number of wet-basement calls are solved by extending downspouts 6 feet from the foundation. Fix the cheap, obvious things first, then install a French drain if water still collects.

What Drives the Price

Depth and length: A deeper trench (for a footing drain) or a longer run obviously costs more in labor and materials. Depth matters most because it dictates how much soil is excavated and hauled.

Soil and access: Rocky or clay soil is slow to dig. A tight backyard where a mini-excavator cannot reach means hand-digging, which multiplies labor. Long carries for gravel add cost too.

Where the water goes: The drain has to discharge somewhere — to daylight on a slope, into a dry well, or to a storm connection. A dry well or pop-up emitter adds material and digging. Daylight discharge is cheapest when the terrain allows it.

Sump pump: Interior systems almost always need a sump pump and basin ($400–$1,200 installed), plus a discharge line and often a battery backup. That is the main reason interior drains cost several times more than exterior ones.

Restoration: Reinstalling sod, replanting beds, or repouring a section of basement slab adds to the final bill. Factor in what the trench crosses.

DIY vs. Professional Installation

An exterior yard or curtain drain is a realistic DIY project if you are fit and have a weekend. The materials — perforated pipe, clean gravel, geotextile fabric — are inexpensive, and renting a trencher ($150–$250/day) speeds up the digging enormously.

DIY makes sense for shallow exterior drains that discharge to daylight. Expect a 40 to 60 foot drain to take two people a full weekend, most of it spent digging and hauling gravel.

Hire a pro for footing drains, interior systems, or any drain that requires deep excavation near the foundation, a sump pump, or breaking concrete. The stakes are high — a botched foundation drain can make water problems worse — and the equipment (excavator, concrete saw) is beyond most DIYers.

A common hybrid: dig and lay an exterior drain yourself, but call a pro if you hit the water table, unstable soil, or utilities. Always call 811 before digging.

Step-by-Step: How a French Drain Is Installed

Step 1 — Plan the slope. The trench must fall at least 1 inch per 8 feet toward the discharge point. Mark the route and confirm the outlet (daylight, dry well, or storm connection) is lower than the start. Call 811 first.

Step 2 — Dig the trench. Typically 12 to 24 inches deep and about 12 inches wide for an exterior drain; deeper for a footing drain. Keep the bottom smoothly graded to maintain the slope.

Step 3 — Line with geotextile fabric. Non-woven landscape fabric lines the trench and wraps up the sides. It lets water through but keeps soil from clogging the gravel — the detail that determines whether the drain lasts 5 years or 30.

Step 4 — Add gravel and perforated pipe. Lay 2 to 3 inches of clean ¾-inch drainage gravel, then the perforated pipe (holes down), then more gravel over the top. Size both with our Retaining Wall Drainage Calculator and Gravel Calculator.

Step 5 — Wrap and backfill. Fold the fabric over the top of the gravel, then backfill with soil (for a buried drain) or leave the gravel exposed with a decorative stone top (for a surface drain). Restore sod or planting as needed.

Sizing the Gravel and Pipe

Getting the quantities right saves multiple trips to the supply yard and ensures your drain actually works. The two materials that matter most are clean drainage gravel and perforated pipe.

Use ¾-inch clean, angular crushed stone — not pea gravel or masonry sand. The angular stone creates open voids that carry water fast and interlock so they do not shift. Round pea gravel packs together and drains poorly.

For pipe, 4-inch perforated corrugated pipe is standard for residential drains. Rigid perforated PVC costs more but resists crushing and is easier to keep straight and sloped — worth it under driveways or heavy soil.

Our Gravel Calculator converts your trench dimensions into tons of stone, and the Retaining Wall Drainage Calculator sizes the gravel and pipe when the drain sits behind a wall. Enter your trench length, width, and depth to get an exact material list.

Common Mistakes That Cause Failure

No slope (or the wrong slope): A French drain moves water by gravity. If the trench is flat or slopes the wrong way, water sits in the pipe and the drain does nothing. Confirm at least 1 inch of fall per 8 feet before you backfill.

Skipping the geotextile fabric: Without fabric, soil migrates into the gravel and clogs the voids within a few years. The fabric is cheap and non-negotiable.

Using the wrong gravel: Pea gravel and fine stone pack tight and drain slowly. Use angular ¾-inch clean crushed stone for open, fast-draining voids.

Perforations facing up: In most residential drains the pipe perforations face down so water enters from the bottom of the gravel bed and the pipe fills from below. Facing them up lets the pipe run full only after the gravel is already saturated.

No real outlet: A drain that dead-ends into buried gravel with nowhere to discharge just relocates the puddle underground. Always terminate at daylight, a dry well sized for the flow, or an approved storm connection.

French Drains and Retaining Walls

French drains and retaining walls go hand in hand. Poor drainage is the number one cause of retaining wall failure — water builds up behind the wall, and the resulting hydrostatic pressure eventually pushes it over. Every properly built retaining wall includes a drainage system that is essentially a French drain behind the wall.

If you are building or repairing a wall on a slope, plan the drainage at the same time. A perforated pipe in clean gravel behind the wall, wrapped in geotextile fabric and sloped to daylight, is exactly the French-drain detail described above.

For a full walkthrough of wall drainage in context, see our guide on how to build a retaining wall on a slope, which covers the buried base, gravel backfill, and drain-to-daylight outlet step by step.

To size everything at once, use our Retaining Wall Drainage Calculator for the gravel and pipe behind the wall, the Gravel Calculator for base and backfill stone, and the Retaining Wall Calculator for the blocks themselves.