French Drain Installation Cost Calculator — 2026 Exterior & Interior
Price a 2026 French drain install by type (exterior perimeter, interior basement, or yard surface), length, depth, and site obstacles — then line up 3 licensed drainage contractor bids.
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Frequently Asked Questions
Q
How much does French drain installation cost in 2026?
National average $10–$65 per linear foot depending on type and depth. Yard surface drains $20–$60/LF; exterior perimeter / foundation weeping-tile $30–$80/LF; interior basement under-slab $45–$100/LF. A typical 50–100 LF residential job runs $2,000–$9,000 installed; full basement systems can reach $10,000–$18,000.
Yard surface drain: $20–$60/LF
Exterior perimeter: $30–$80/LF
Interior basement: $45–$100/LF
Typical 50–100 LF job: $2,000–$9,000
Full basement system: up to $18,000
Drain Type
$/LF Installed
Typical 75 LF Total
Yard surface / curtain drain
$20–$60
$1,500–$4,500
Exterior perimeter (foundation)
$30–$80
$2,250–$6,000
Interior basement (under-slab)
$45–$100
$3,400–$7,500
Deep weeping tile to footing
$50–$110
$3,750–$8,250
Q
What’s the difference between interior and exterior French drains?
Exterior drains are buried along the outside of the foundation down to footing depth and catch water before it reaches the wall. Interior drains run inside the basement under the slab and collect water that already breached the wall, then route it to a sump pump. Interior installs cost 30–50% more per linear foot because crews must saw-cut and repour concrete, and nearly always include a $800–$2,500 sump pump.
Exterior: catches water before it reaches the wall
Interior: collects water already inside, routes to sump
Exterior needs deep excavation (6–8 ft)
Interior needs slab saw-cut + repour
Interior almost always needs a sump pump
Q
Do I need a sump pump with a French drain?
Almost always for interior basement drains ($800–$2,500 installed). Exterior perimeter drains can sometimes daylight downslope to a lower grade point without a pump if your lot drops enough. Yard surface drains usually drain to daylight or a dry well. The pump becomes mandatory any time the collection pipe sits below grade with nowhere gravity-fed to discharge.
Interior basement: pump almost always needed
Exterior perimeter: pump if no daylight outlet
Yard surface: usually gravity to daylight or dry well
Sump pump installed cost: $800–$2,500
Battery backup pump: +$200–$600
Q
How deep does a French drain need to be?
Yard surface drains run 12–18 inches deep. Standard exterior perimeter drains run 3–6 feet. Full weeping-tile systems run down to the foundation footing, usually 7–8 feet. Deeper trenches cost more because they need shoring in loose soil, slower digging, and haul-off of more spoils — budget +15–30% for standard depth and +30–50% for footing depth over a shallow yard install.
Yard surface: 12–18 inches deep
Standard exterior: 3–6 feet
Full weeping tile: 7–8 feet (footing)
Standard depth premium: +15–30%
Footing depth premium: +30–50%
Q
Does homeowners insurance cover French drain installation?
No — French drains are classified as preventive home improvements, not insurance-covered repairs. Insurance may pay to repair finished basement damage after a sudden covered event (like a burst pipe) but not to prevent future seepage. Some lenders will finance drainage work through a home-equity line; FHA 203(k) loans can roll drainage into a broader renovation package.
Not covered by standard homeowners policy
Classified as preventive improvement
Finished basement damage: may be covered if sudden event
HELOC / home equity line: common financing route
FHA 203(k): can bundle with other renovations
Q
What’s a fair deposit for a French drain contractor?
Reputable drainage contractors cap deposits at 10–25% of the project. On a $6,000 exterior install that is $600–$1,500. Demands above 30–50% upfront, or cash-only pricing, are standard scam signals — walk away. Verify license, general-liability certificate, and workers’ comp before signing. Get at least 3 written quotes and ask for 3 recent local references you can call.
175 LF exterior perimeter drain, open side yard, Midwest
Inputs
Drain typeExterior perimeter (foundation)
Length75 LF (50–100 ft)
DepthStandard 4–6 ft
ObstaclesEasy / open yard
Result
Typical installed quote$3,000 – $5,500
Trenching + gravel + perf pipe~$2,400
Filter fabric + stone cap~$600
Sod restoration~$400
260 LF interior basement drain with sump pump, Northeast
Inputs
Drain typeInterior basement (under-slab)
Length60 LF
DepthStandard 4–6 ft
ObstaclesModerate (concrete saw-cut)
Result
Typical installed quote$4,500 – $8,000
Slab saw-cut + removal~$1,200
Gravel bed + drain tile~$1,800
Sump pump installed~$1,400
Concrete repour~$1,000
3120 LF yard surface drain, rock-heavy lot, West
Inputs
Drain typeYard surface / curtain
Length120 LF (100+ ft)
DepthShallow 3 ft
ObstaclesDifficult (rock, tight access)
Result
Typical installed quote$4,200 – $7,800
Rock excavation surcharge+50–100%
Pop-up emitter / daylight outlet~$300
Formulas Used
French drain installed cost driver breakdown
Quote = (Base $/LF by type × Length) × Depth multiplier × Obstacle multiplier + Sump/Extras
French drain quotes start from a per-linear-foot base rate that depends on drain type (yard $20–$60, exterior perimeter $30–$80, interior basement $45–$100). Multiply by trench length, apply a depth surcharge (+15–30% for 4–6 ft, +30–50% for footing depth), apply an obstacle multiplier (+25–60% moderate, +50–100% hard), then add a sump pump ($800–$2,500) for interior jobs and any landscape-restoration line items.
Where:
Base $/LF= Yard $20–$60, exterior $30–$80, interior $45–$100
Depth multiplier= Shallow 1.0x, standard 1.15–1.3x, footing 1.3–1.5x
Obstacle multiplier= Open yard 1.0x, moderate 1.25–1.6x, difficult 1.5–2.0x
French Drain Installation Costs in 2026: Interior, Exterior, and Yard Drains
1
French Drain Cost in 2026: The Three Install Types
French drains in 2026 split into three install types with very different price structures. Yard surface drains — shallow trenches 12–18 inches deep that move surface water away from low spots or downspout runoff — run $20–$60 per linear foot installed. Exterior perimeter drains (also called foundation drains or weeping tile) run along the outside of the foundation 3–8 feet deep and cost $30–$80 per linear foot. Interior basement drains, buried under the slab inside the basement and routed to a sump pump, are the most expensive at $45–$100 per linear foot because crews must saw-cut and repour concrete. A typical 50–100 LF residential job lands $2,000–$9,000 installed; full-perimeter basement systems with pumps and vapor barriers can reach $10,000–$18,000.
The calculator above lets you price a specific scope in minutes, but most homeowners undershoot because they only budget for the trench itself. Real quotes include six line items: trenching labor, gravel and fabric, perforated pipe, tie-ins and daylight outlet (or sump pump for interior jobs), landscape restoration, and permit/fees. A cheap quote that omits restoration or the pump will blow past budget by 20–35% when the final invoice lands. Compare the drainage scope against a broader project using the home renovation estimator when the drain is part of a larger basement-finishing or exterior-improvement package.
Source data in this guide comes from Angi, HomeGuide, Fixr, LawnStarter, and Bob Vila 2026 pricing surveys.
French drain installed cost by type and length, 2026. Source: Angi, HomeGuide, Fixr.
Type
$/LF Installed
75 LF Total
150 LF Total
Yard surface drain
$20–$60
$1,500–$4,500
$3,000–$9,000
Exterior perimeter
$30–$80
$2,250–$6,000
$4,500–$12,000
Interior basement
$45–$100
$3,400–$7,500
$6,750–$15,000
Deep weeping tile to footing
$50–$110
$3,750–$8,250
$7,500–$16,500
Interior basement French drains run 30–50% more per linear foot than exterior perimeter drains because the crew has to saw-cut and repour slab concrete. Both are effective — pick exterior when you can still excavate outside, interior when you can’t.
2
What Drives the $20 to $100 Per Foot Spread
Four factors explain most of the 5x price range: drain type, length, depth, and site conditions. Drain type is the single biggest driver because it determines whether the crew is working in open soil (yard), deep excavation (exterior), or inside a poured slab (interior). Length scales near-linearly, but jobs under 50 LF usually carry a minimum-trip surcharge of $400–$800, while jobs over 100 LF often earn a 10–15% volume discount because the crew is already on site with equipment staged.
Depth and obstacles behave as multipliers on top of the base per-foot rate. A shallow yard drain at 3 feet is baseline; a standard 4–6 foot perimeter adds 15–30%; a full footing-depth weeping tile at 7–8 feet adds 30–50% and sometimes requires trench shoring or hand-dig near utilities. Obstacles escalate fast: an open side yard is 1.0x, existing landscaping and concrete walkways to saw-cut push costs 25–60% higher, and tight-access lots with buried utilities, bedrock, or no machine path can double the per-foot rate.
Drill into the depth and obstacle lines in every bid — these are the two places contractors diverge most, and the two places cheap bids skip scope. A $4,000 bid that assumes open-yard trenching on a lot that actually has 40 feet of concrete walkway and a buried gas line will come in at $5,500–$6,500 actual. Always walk the trench line with the contractor before signing and ask them to price the specific obstacles in writing.
Regional labor adds another 20–30% spread coast to coast. Northeast and coastal California markets price 20–30% above Midwest and South benchmarks, mostly because disposal tipping fees and mobilization costs are higher in urban metros. If you’re near the top of a bid range, the calculator’s ZIP-based regional adjustment is typically accurate to within 10–15%.
Common add-ons and surcharges on top of the base French drain price, 2026.
Cost Add-On
Typical Range
When Triggered
Sump pump install (interior)
$800–$2,500
Almost every interior basement drain
Battery backup pump
+$200–$600
Flood-prone markets or finished basement
Trench shoring
$500–$2,000
Footing-depth in loose soil, sandy or clay lots
Concrete saw-cut + repour
$1,000–$3,000
Interior slab, or exterior crossing a walkway
Rock / bedrock excavation
+50–100% of trench cost
Lots with surface rock or shallow bedrock
Permit + grading inspection
$150–$1,200
Often required for footing-depth work
Landscape restoration
$200–$1,500
Sod, plants, or hardscape replacement
Drain type: biggest factor (yard cheapest, interior most expensive)
Length: volume discount at 100+ LF; minimum-trip surcharge under 50 LF
Depth: shallow baseline, standard +15–30%, footing +30–50%
Obstacles: open yard 1.0x, moderate 1.25–1.6x, difficult 1.5–2.0x
Regional labor: Northeast + West coast +20–30% over Midwest/South
Restoration: sod, walkway repour, or plant replacement adds $200–$1,500
3
Interior vs Exterior French Drain: Which to Pick
The choice between interior and exterior basement French drains is usually driven by site access, not preference. Exterior perimeter drains are mechanically better because they stop water before it reaches the foundation wall — you get a dry wall, not just a dry floor. They require digging a trench around the full perimeter 6–8 feet deep, which means moving shrubs, concrete walks, decks, and sometimes the AC condenser pad. Total cost for a full-perimeter exterior drain on a typical 150 LF foundation footprint runs $4,500–$12,000 with full restoration.
Interior drains are the practical choice when exterior access is impossible — a zero-lot-line house touching a neighbor, a finished deck or hardscape that would cost more to tear out than the drain itself, or a walk-out basement where half the perimeter is below grade. They sit under the slab inside the basement, collect water that has already breached the wall, and route it to a sump pump. You get a dry basement floor but the wall itself stays wet. Interior installs run $6,750–$15,000 on a 150 LF perimeter including the sump pump, saw-cut, and slab repour.
A hybrid approach — exterior on the accessible sides, interior on the blocked sides — is common on tight lots and typically lands within 10% of the cost of either pure approach. For a second opinion on scope, the attic insulation calculator covers the upper-envelope work that often gets bundled with basement waterproofing for whole-house moisture control; drainage contractors will often bid both if you ask.
Exterior French drains give you a dry foundation wall; interior drains give you a dry basement floor. Pick exterior when you have site access; interior when you don’t; hybrid when access is mixed.
1
Confirm the moisture source
Surface runoff, hydrostatic pressure from saturated soil, or plumbing leak. Different sources need different drains.
2
Check exterior access
Can the crew dig a 6–8 ft trench around the full perimeter? Blocked sides push toward interior or hybrid.
3
Price both approaches
Get one exterior bid, one interior bid, and ask a third contractor for hybrid pricing.
4
Verify the daylight outlet
Exterior drains need a gravity outlet; if there isn’t one, you end up with a sump pump either way.
A clean exterior perimeter French drain quote decomposes into six buckets on a typical $6,000 build: excavation and trenching 30%, gravel and filter fabric 15%, perforated pipe and fittings 8%, daylight outlet or sump tie-in 12%, landscape and hardscape restoration 20%, and permit plus contingency 15%. Interior basement builds shift the mix — the excavation line becomes concrete saw-cut and repour (typically 25–30% of total), the sump pump adds $800–$2,500 as its own line, and landscape restoration drops to near zero because the work is all inside.
The donut chart visualizes the typical exterior breakdown. When you receive multiple bids, recast each into these buckets and outliers become obvious. A bid where the trenching line looks materially below 25% on an exterior job is either bundling labor into materials or skipping the full footing depth — both red flags. A bid where restoration is missing entirely will land 15–20% over the written number once the homeowner negotiates sod and walkway repair post-install.
Pay special attention to the gravel and fabric spec. Cheap bids skip the filter fabric wrap on the pipe, which lets silt infiltrate and clog the perforations in 3–5 years. Proper spec: 2–4 inches washed #57 or #2 stone with non-woven filter fabric (geotextile) wrapping the entire gravel envelope, not just the pipe. Confirm the stone grade and the fabric spec in writing — the cost difference between proper and cheap is $200–$500 on a typical job and saves a $3,000 re-dig in year 5.
Daylight outlets are the single most commonly underspecified part of the job. A proper outlet has a rodent guard, a pop-up emitter, and at least 10 feet of solid (non-perforated) pipe from the gravel envelope to the emitter to prevent root intrusion. Cheap bids use perforated pipe all the way out and a simple open end — these clog with roots and sediment within 2–4 years and force the homeowner to dig up 20–30 LF to rebuild the outlet. Ask explicitly for a pop-up emitter and rodent guard on the bid.
5
Red Flags and Mistakes When Hiring a Drainage Contractor
Drainage work is scam-prone because dollar amounts are substantial ($3,000–$15,000 typical) and the finished work is buried — once the crew covers the trench, the homeowner has no way to verify depth, stone grade, fabric wrap, or pipe slope. Reputable contractors cap deposits at 10–25%; demands above 30–50% upfront, or cash-only pricing, are near-universal scam signals. On a $6,000 exterior install, a $600–$1,500 deposit is normal; anything above $2,000 before work starts is the deposit scam pattern.
The single biggest documentation mistake is signing a bid that doesn’t specify pipe slope, stone grade, or filter-fabric spec. Proper slope for French drain pipe is 1% minimum (1 inch of fall per 10 feet of run); anything less clogs with silt. Proper stone is washed #57 or #2; cheap contractors sometimes substitute crushed concrete or unwashed river rock, which clogs in 3–5 years. Non-woven geotextile fabric must wrap the entire gravel envelope, not just the pipe. If the bid doesn’t spell these out, the installed drain will fail inside a decade and leave you with a $4,000–$8,000 re-dig bill.
Photograph the open trench with stone, pipe, and fabric visible BEFORE the contractor backfills. Every reputable drainage contractor expects the homeowner to photograph the buried work — a contractor who refuses or pressures you to let them backfill before you’ve seen the stone and fabric is hiding shortcuts. If they resist, stop the job and get a second contractor to finish. The cost of a mid-job contractor swap is 15–25% extra; the cost of a buried bad install is 100% plus the re-dig. Drainage consultations often surface related structural work — if your contractor mentions footing cracks or settling, price the structural scope separately with the foundation calculator before letting drainage crews backfill.
Two specific scams to watch for. First, post-storm door-knockers offering "today-only" drainage pricing after a heavy-rain event in the neighborhood — these are traveling crews with no permanent address. Second, "waterproofing contractors" who pivot from a free basement inspection to a $25,000 whole-system bid — legitimate drainage work is almost always priced per linear foot with itemized line items, not as a proprietary "system" with a lump-sum price and a pressure close.
Buried work is the easiest place to cut corners on a job site. Photograph the open trench with stone, pipe, and fabric visible before the crew backfills. No reputable drainage contractor refuses this — it protects both sides of the contract.
Deposit cap 10–25%; 50%+ upfront = scam signal
Verify license, general-liability, and workers’ comp before signing
Bid must spec pipe slope (1%+), stone grade (#57 / #2 washed), and filter fabric
Photograph the open trench with stone and fabric BEFORE backfill
Walk away from post-storm door-knockers and "today-only" pricing
Legitimate drainage bids are itemized per linear foot, not lump-sum "system" quotes
Get 3 written bids; discard any bid 20%+ below the pack (skipped scope)
6
Slope, Outlet Design, and the Common Re-Dig Mistakes
Nearly every failed French-drain install traces back to one of three slope-or-outlet errors that cost $1,500–$5,000 to re-dig. First: insufficient pitch. A French drain requires a continuous 1–2% fall (1–2 inches per 10 feet) from the highest catchment point to the discharge outlet — most DIY installs start at 0.5% and back up after the first winter. Always set the trench depth with a laser level (rented $30/day) rather than eyeballing against the grade; grade slopes don’t match the desired water path in most yards.
Second: outlet termination. The drain has to discharge to daylight (a downslope point 10+ feet from the foundation), a properly sized dry well (minimum 20 cubic feet of capacity per 1,000 sqft of contributing roof/yard area), or a storm-sewer stub where municipally permitted. Discharging to a flowerbed, lawn, or “where the water usually pools” recreates the original problem 3–12 months later. Daylight outlets must include a rodent-exclusion grate with ¼-inch openings and rigid PVC rather than flexible corrugated for the last 10 feet — otherwise silt, roots, or a mouse nest restores the blockage within two years.
Third: fabric and aggregate selection. Woven monofilament geotextile fabric (Mirafi 140N, US Fabrics US 160NW, or TerraTex NW30) lines the entire trench — spunbonded non-woven is acceptable only in sandy soils. The aggregate must be washed ¾-inch angular stone, NOT pea gravel; round gravel compacts and restricts flow. A 6-inch perforated pipe with the perforations pointing DOWNWARD (not up as many DIY guides show) sits on 4–6 inches of stone with another 4–6 inches above before fabric wrap and soil cap. A properly spec’d install lasts 25–40 years; a shortcut spec clogs in 3–10. For broader drainage planning, pair this with the basement waterproofing cost calculator or sump pump install cost calculator.
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.
