If water is pooling in your yard, seeping into your basement, or turning your crawl space into a swamp, you've probably heard someone recommend a French drain. Good news — it's one of the most cost-effective drainage solutions out there. But depending on where you install it and how big your property is, costs can swing pretty dramatically.
The short version: French drains cost $20 to $75 per linear foot installed, and most homeowners spend between $2,000 and $15,000 total. Exterior systems on the cheaper end, interior systems on the higher end. Let's break all of this down so you know exactly what you're paying for.
Cost Per Linear Foot: Exterior vs Interior
The biggest cost driver is where the drain goes — outside your foundation or inside your basement floor. Here's how those compare:
| Type | Cost Per Linear Foot | Best For |
|---|---|---|
| Exterior French Drain | $20 – $45 | Yard drainage, surface water, slope issues |
| Interior French Drain | $40 – $75 | Basement water intrusion, hydrostatic pressure |
| Interior + Sump Pump | $55 – $100 | Chronic basement flooding, high water table |
Interior drains cost more because contractors have to jackhammer your concrete floor, dig a trench along the perimeter, lay pipe, and then pour new concrete over it. It's labor-intensive work, and you can't really DIY it safely without serious experience.
Total Project Costs by Footage
Want to get a ballpark for your specific situation? Here's what typical projects run based on footage:
| Linear Feet | Exterior (Low–High) | Interior (Low–High) |
|---|---|---|
| 50 feet | $1,000 – $2,250 | $2,000 – $3,750 |
| 100 feet | $2,000 – $4,500 | $4,000 – $7,500 |
| 200 feet | $4,000 – $9,000 | $8,000 – $15,000 |
These numbers assume professional installation. If your yard has poor access, rocky soil, or tree roots everywhere, expect to add 20-30% to those figures.
Interior vs Exterior: Which One Do You Actually Need?
This is where a lot of homeowners get confused — or worse, get sold something they don't need. Here's the honest breakdown:
Exterior French Drain
- Redirects surface and subsurface water away from your home before it hits the foundation
- Best for: yard flooding, wet spots, soggy lawn, water running toward the house
- Usually combined with proper grading and downspout extensions
- Less disruptive — no breaking up your floors
- Can double as a landscaping feature with decorative gravel
Interior French Drain (Perimeter Drain)
- Manages water that's already gotten in — routes it to a sump pump rather than preventing entry
- Best for: finished or unfinished basements with active water intrusion, hydrostatic pressure through walls/floor
- More invasive and more expensive, but more effective for severe water problems
- Typically includes a sump pump and discharge line
Bottom line: if the water problem is in your yard, go exterior. If it's in your basement and you're seeing water seeping through the walls or floor, interior is what you need.
What's Included in a French Drain Installation?
When you get a quote from a contractor, here's what should be included:
- Excavation: Digging the trench, which is often the biggest labor cost
- Perforated pipe: Usually 4-inch PVC or flexible corrugated pipe
- Filter fabric/geotextile: Wraps the pipe to prevent soil from clogging it
- Gravel/aggregate: Surrounds the pipe for proper drainage flow
- Outlet/discharge point: Where the water actually goes — a drain, dry well, or daylight outlet
- Backfill and grading
For interior systems, add concrete cutting, jackhammering, concrete patching, and typically a sump pump pit and pump.
Adding a Sump Pump: Extra Cost and Value
If you're doing an interior system, you almost certainly need a sump pump too. A sump pump installation typically adds $1,000 to $3,000 depending on pump type and labor. Battery backup systems add another $300-$500 but are well worth it — your basement flooding during a power outage (when storms hit hardest) is a real scenario.
Combination packages from waterproofing companies often bundle interior drain + sump pump for $8,000-$15,000. Get at least three quotes — prices vary enormously in this industry.
Comparing Drainage Solutions
| Solution | Cost Range | Best For | Lifespan |
|---|---|---|---|
| French Drain | $2,000 – $15,000 | Subsurface water, basement flooding | 30–40 years |
| Dry Well | $1,000 – $5,000 | Concentrated runoff (downspouts) | 10–20 years |
| Swale/Grading | $500 – $3,000 | Surface water direction | Ongoing |
| Catch Basin | $1,500 – $4,000 | Low spots with standing water | 20–30 years |
Can You DIY a French Drain?
For exterior yard drains? Yes, absolutely — if you're handy and have a weekend to spare. You can rent a trencher for $150-$300/day, buy perforated pipe and gravel at any home improvement store, and handle a basic 50-100 foot exterior system yourself for $500-$1,500 in materials.
For interior basement systems? Honestly, no — unless you have concrete cutting experience. Jackhammering basement floors incorrectly can compromise your foundation, and improper installation means you'll just have to redo it. The cost savings aren't worth the risk.
Signs You Actually Need a French Drain
- Standing water in your yard that takes more than 24 hours to drain after rain
- Wet or damp basement walls, efflorescence (white mineral deposits) on concrete
- Musty smell in basement or crawl space
- Erosion patterns in your yard suggesting water flow issues
- Soggy lawn even without recent rain
- Water damage to fence posts, outbuildings, or retaining walls
- Neighbors with similar issues (drainage problems are often neighborhood-wide)
Permits and Regulations
Here's something many homeowners skip and regret: exterior French drains over 100 feet often require a permit in most jurisdictions, especially if they connect to municipal stormwater systems. Interior systems almost always require a permit since they involve structural work (cutting concrete).
Permit costs are typically $100-$500. More importantly, unpermitted drainage work can cause problems when you sell — buyers' inspectors find this stuff. Check with your local building department before starting.
How Long Does a French Drain Last?
A properly installed French drain with quality materials should last 30-40 years. The main enemies are root intrusion (from trees and shrubs — keep plantings away from the drain line), silt buildup if the filter fabric fails, and settlement that changes the drain slope. Most contractors offer a 10-year warranty on labor; the pipe itself is nearly indefinite if not physically damaged.
Frequently Asked Questions
Q. Does a French drain increase home value?
Indirectly, yes — it prevents the kind of water damage that dramatically reduces home value. A home with documented water intrusion history can sell for 10-20% less than comparable dry homes. Solving the problem before listing is almost always worth it. Some buyers specifically ask about drainage, especially in flood-prone areas.
Q. How do I know if my French drain is working?
After a heavy rain, walk the area. Water should not be pooling where it used to. For basement systems, your sump pump should be activating and the floor/walls should stay dry. You can also do a simple test: run a garden hose for 30 minutes in the problem area and watch whether water drains away within a few hours.
Q. What's the difference between a French drain and a trench drain?
A French drain is a buried perforated pipe surrounded by gravel — it collects subsurface water. A trench drain (also called a channel drain) is a surface-level linear drain with a grate on top that collects surface runoff. Many drainage solutions use both — a trench drain at the surface that feeds into a French drain below.
Q. How deep does a French drain need to be?
For yard drainage, typically 18-24 inches deep. For foundation protection (exterior), you want the pipe at or below the footing level, which can mean 4-6 feet deep depending on your foundation depth. Interior basement drains go just below the slab, typically 12-18 inches.