The average French drain cost is about $5,000 installed, with most projects between $2,800 and $6,500. Exterior yard drains typically run $10–$75 per linear foot. Interior basement drains, which need concrete cutting, cost about $40–$100 per linear foot. Length, depth, soil and what's in the way decide the final price.
What is a French drain?
A French drain is a sloped trench filled with gravel, usually with a perforated pipe at the bottom and fabric around the stone. It collects groundwater and surface water and carries it by gravity to a safe outlet: a dry well, a daylight point downhill, a storm system where permitted, or a sump pit.
You might need one if you have:
- A soggy yard that stays wet days after rain
- Water pooling against the foundation
- A damp or leaking basement
- Runoff from a neighbor's higher lot or a hillside
French drain cost per linear foot
| Drain type | Cost per linear ft | 100 ft | 200 ft |
|---|---|---|---|
| Exterior (yard or foundation perimeter) | $10–$75 | $1,000–$7,500 | $2,000–$15,000 |
| Interior (basement perimeter) | $40–$100 | $4,000–$10,000 | $8,000–$20,000 |
Interior basement French drain cost
Inside the basement, crews cut and remove a strip of the slab along the walls, dig a trench, lay perforated pipe in gravel and lead it to a sump pit. Then they re-pour the concrete. A sump pump adds roughly $625–$2,625. Interior systems manage water that's already entered the foundation, rather than stopping it outside.
For finished basements, factor in removing and rebuilding walls and flooring at the perimeter. If you're planning to finish the space, install drainage first. See our basement renovation guide.
What affects French drain cost
- Length and depth: longer and deeper trenches mean more digging and gravel. Going at least about 2 feet deep is commonly recommended for proper drainage.
- Soil: rocky or heavy clay soil raises labor costs; loose soil lowers them
- Access: hand-digging in tight side yards costs more than machine trenching in open lawns
- Obstacles: utilities, tree roots, patios and driveways along the route
- Outlet: a simple daylight outlet is cheapest; dry wells, catch basins and pump systems add cost
- Restoration: topsoil (about $11–$53 per cubic yard), sod ($0.90–$1.80 per sq ft) or seed afterward
Materials for a DIY French drain
A typical DIY example for a 25-ft drain, 10 inches wide and 18 inches deep, totals about $528, or roughly $21 per linear foot. That includes:
- Gravel
- 4-inch perforated pipe
- Catch basin
- Non-woven landscape fabric
- Trencher and sod-cutter rental
Call 811 before you dig so underground utilities are marked. It's free and required in most states.
Use our Gravel Calculator or Pea Gravel Calculator for stone. Multiply trench length × width × depth (in feet) ÷ 27 for cubic yards, minus the pipe's volume.
Slope: the make-or-break detail
A French drain only works if it drains. The pipe needs continuous fall toward the outlet. Many installers aim for at least about 1% (⅛ inch per foot) and more where possible. The Slope Calculator shows how much drop your run needs.
Alternatives and add-ons
- Regrading the soil to slope away from the house can be cheaper when the problem is surface water
- Downspout extensions or buried downspout lines fix roof-water problems
- Curtain drains are shallower drains (about 9–12 inches) that intercept surface runoff uphill
- Dry wells store and slowly release water where there's no downhill outlet
- Retaining walls on slopes need drainage behind them. See retaining wall cost.
Local rules
You generally can't redirect water onto a neighbor's property. Many towns also restrict connecting drains to sanitary sewers. In New York City, discharges to the sewer system are regulated by the Department of Environmental Protection. Check with your local building or public works department before choosing an outlet.
When the problem is the foundation
If water comes through cracks, or walls are bowing, drainage may be only part of the fix. See foundation repair cost for waterproofing and structural repair prices.
Frequently asked questions
How much does a 100-foot French drain cost?
About $1,000–$7,500 for an exterior drain and $4,000–$10,000 for an interior basement drain.
How long does a French drain last?
A well-built drain with fabric-wrapped stone can work for many years. Clogging from fine soil is the main cause of failure, which is why fabric matters.
Is a French drain worth it?
If water is damaging your foundation, basement or landscaping, usually yes. It's often much cheaper than repairing water damage repeatedly.
Can I install a French drain myself?
Short, shallow yard drains are a reasonable DIY project. Interior drains, deep foundation drains and sump systems are best left to professionals.
National averages for planning only.
