French Drain Cost: Interior vs Exterior Pricing Guide (2025)

French Drain Cost: What to Budget by Type and Length

A French drain costs $10-$100 per linear foot depending on whether it goes outside in the yard or inside under the basement slab. Exterior drains run $500-$8,800 installed, while interior perimeter drains run $4,000-$17,000 because they require jackhammering the slab. This guide breaks down both, including the added cost of a sump pump.

By the FoundationQHub Editorial Team | Reviewed by James M., Home Services Research Editor | Last updated: 2026-07-01

Low end

$500

Typical range

$500 - $17,000

High end

$17,000+

Cost ranges are estimates based on industry data. Actual costs depend on your local market, soil conditions, severity, and contractor. Get quotes for your specific situation.

What a French Drain Is and How It Works

A French drain is a gravel-filled trench with a perforated pipe at the bottom that intercepts subsurface water and uses gravity to carry it to a discharge point. The pipe is wrapped in geotextile filter fabric and surrounded by clean washed gravel, typically 3/4” to 1-1/2”, so water flows in freely while silt stays out. The trench slopes about 1 inch per 10 feet toward the outlet.

There are two versions, and the difference is the single biggest factor in price.

Exterior (curtain drain): Sits around the footing outside the foundation and keeps water from ever reaching the wall.

Interior (drain tile / weeping tile): Runs the basement perimeter beneath the slab, capturing water that has already reached the footing and routing it to a sump pit. This is the choice when water is collecting around the foundation but outside excavation is blocked by decks, driveways, or property lines.

Cost Breakdown

Per Linear Foot

Type	Cost Per Linear Foot
Exterior (yard / curtain drain)	$10-$35
Interior (under-slab basement perimeter)	$40-$100
Interior with sump pump	$50-$100

Interior drains cost more per foot because they require jackhammering the slab and re-pouring the concrete edge after the pipe is set. That concrete removal and replacement is the big multiplier.

Whole-Project Pricing

Type	Installed Total
Exterior drain	$500-$8,800
Interior perimeter drain	$4,000-$17,000
Sump pump addition	Add $600-$2,500

What Drives Cost Up

Interior vs exterior: The concrete removal on an interior drain is the largest single cost driver. Breaking out and re-pouring the slab perimeter turns a modest trench into a major project.

Trench length and depth: Cost scales with linear footage, and deeper trenches to reach the footing add labor.

Soil and rock: Rocky or hard soil slows digging and raises the per-foot rate.

Discharge endpoint: Daylighting to grade is cheapest. Routing to a sump pit or a dry well adds pump, pit, and piping cost.

Landscaping and hardscape restoration: Exterior drains that cross lawns, patios, or driveways add restoration cost after backfill.

Permits: Some jurisdictions require permits for drainage work and sump discharge, adding fees.

Project Cost Scenarios

Scenario	Type	Estimated Cost
40 ft wet-yard curtain drain	Exterior	$500-$1,400
120 ft exterior foundation drain	Exterior	$1,800-$5,000
100 ft interior basement perimeter	Interior	$4,000-$10,000
150 ft interior perimeter	Interior	$6,500-$15,000
Interior perimeter + sump pump	Interior	Add $600-$2,500

French Drain vs Alternatives

Method	Cost Range	Best For	Excavation?
Exterior French drain	$500-$8,800	Stopping water before it reaches the wall	Yes (around footing)
Interior French drain	$4,000-$17,000	Managing water when outside digging is blocked	No exterior; slab removal inside
Sump pump only	$600-$3,000	Removing pooled water when there is a pit	No
Exterior wall waterproofing	$15,000-$40,000	Sealing the wall itself against seepage	Yes (full excavation)

Choose an exterior drain when:

You want to keep water away from the wall entirely
The yard has room to dig and a spot to daylight the outlet
Landscaping and hardscape restoration is manageable

Choose an interior drain when:

Decks, driveways, patios, or property lines block outside excavation
Seepage shows up at the floor-wall cove joint
You already need a sump system

Add a sump pump when:

The drain cannot daylight to a point lower than the pipe
You have an interior perimeter drain (a sump is almost always required)

What to Look for in a French Drain Quote

A complete quote should specify:

Linear footage and whether the price is per foot or a flat project total
Interior vs exterior, and for interior work, slab removal and re-pour included or excluded
Pipe type and that it is wrapped in geotextile filter fabric
Gravel spec (clean washed, 3/4” to 1-1/2”)
Trench slope toward the outlet (about 1 inch per 10 feet)
Discharge endpoint: daylight, sump pit, or dry well, and whether a sump pump is included
Landscaping or hardscape restoration included or billed separately
Permits pulled by the contractor or left to you
Warranty on the system and the dry-basement guarantee, if any

Ask specifically whether filter fabric is included on every run. Skipping it is the cheapest way for a contractor to shave the bid, and it is the number one reason drains silt up and clog years later.

When a French Drain Is Not the Right Fix

A French drain manages subsurface water, so it does not solve every wet basement. It will not stop water entering high on the wall, water coming through wall cracks, or moisture caused by bad grading and gutters, because none of that water reaches the drain. An interior drain manages water rather than keeping it out of the footing. If your water problem starts above the floor line, a grading, gutter, or wall-crack repair is the real fix, and a drain would be money spent on the wrong symptom.

Frequently Asked Questions

Interior vs exterior French drain, which do I need?

It depends on where the water is and what access you have. An exterior French drain (also called a curtain drain) sits around the footing outside and keeps water from ever reaching the wall, at $10-$35 per linear foot. It is the better long-term fix but requires digging around the foundation. An interior French drain runs the basement perimeter beneath the slab and captures water that already reached the footing, routing it to a sump pit, at $40-$100 per linear foot. Choose interior when exterior excavation is blocked by decks, driveways, patios, or property lines, or when finished landscaping makes outside digging impractical.

Do I need a sump pump with a French drain?

You need a sump pump whenever the drain cannot discharge by gravity to a point lower than the pipe, which is almost always the case with an interior basement drain. An interior perimeter drain collects water in a sump pit, and the pump lifts it out and away from the house. An exterior drain can often daylight to a lower spot in the yard and skip the pump entirely. Adding a sump pump raises the price to $50-$100 per linear foot and adds $600-$2,500 for the pump, pit, and discharge line.

How long does a French drain last before it clogs?

A properly built French drain lasts 30 to 40 years, and often the life of the house, when the perforated pipe is wrapped in geotextile filter fabric and surrounded by clean washed gravel. The filter fabric is what keeps silt and fine soil out of the pipe. Drains that skip the fabric, or use dirty gravel, can silt up and clog in as little as 8 to 10 years. Interior drains under a slab are protected from surface debris and tend to last longest. Roots, sediment, and crushed pipe are the usual failure causes.

Can I install a French drain myself, and how much do I save?

A simple exterior yard or curtain drain is a realistic DIY project and can cut cost to $10-$25 per linear foot in materials, saving roughly half versus hiring out. You need to dig a trench that slopes about 1 inch per 10 feet toward the outlet, lay filter fabric, add perforated pipe, and backfill with washed gravel. An interior basement drain is not a DIY job: it requires jackhammering the slab, tying into a sump system, and re-pouring concrete, so leave that to a contractor. Underestimating the slope or skipping filter fabric is the most common DIY mistake and leads to early clogging.

Does a French drain fix a wet basement permanently?

A French drain permanently manages the water it is designed to intercept, but it is not a cure for every wet basement. It works well against chronic hydrostatic pressure, a high water table, and seepage at the floor-wall cove joint. It does not fix water entering high on the wall, water coming through wall cracks, or problems caused by bad grading and gutters, because that water never reaches the drain. An interior drain manages water rather than keeping it out of the footing. Pair the drain with surface fixes like grading and downspout extensions for a lasting dry basement.