French drain cost dataset
This is the complete dataset behind the French drain calculator. The single most useful thing in it is that almost none of the money is in the pipe. It is in the trench: the machine, the operator, the gravel by the ton, and putting the surface back. That is why three drains with the same name cost so differently. Last reviewed 2026-08-22.
Cost by length and drain type
National figures with a daylight outlet and one surface inlet. The per-foot column is the one worth reading: it falls as the run gets longer, because mobilisation and the outlet are paid once whatever the length.
| Length | Yard drain | Exterior footing drain | Interior perimeter drain |
|---|---|---|---|
| 50 ft | $1,603$32/ft | $3,266$65/ft | $3,228$65/ft |
| 100 ft | $2,566$26/ft | $5,798$58/ft | $5,818$58/ft |
| 200 ft | $4,492$22/ft | $10,864$54/ft | $11,090$55/ft |
| 300 ft | $6,463$22/ft | $16,067$54/ft | $16,268$54/ft |
A contractor quoting one flat rate per foot for a long run is quoting above their own cost curve. That is not dishonest, but it is worth asking about, because the difference over 200 feet is real money.
Trench geometry, which is the whole price
Excavation, gravel and disposal are all driven by volume, and volume is depth times width times length. These are the figures the model uses.
| Drain type | Depth | Width | Cubic yards per 100 ft | What that means |
|---|---|---|---|---|
| Yard drain | 2 ft | 1 ft | 7.4 | Shallow, in open ground, to move surface water away. The cheapest of the three by a wide margin. |
| Exterior footing drain | 7 ft | 2 ft | 51.9 | Excavated down the outside of the foundation to the footing. Deep, and the excavation dominates. |
| Interior perimeter drain | 1.5 ft | 1 ft | 5.6 | Cut through the basement slab around the inside perimeter. No excavation outside, but the slab has to be broken out and re-poured. |
An exterior footing drain is dug to the base of the foundation, so its depth is set by your basement rather than by choice. That single number is why it costs more than double a yard drain of identical length.
Where the water is sent
| Outlet | What it needs |
|---|---|
| Daylight outlet | Gravity to a lower point on the property. Cheapest, and needs the slope to exist. |
| Dry well | A buried gravel or chamber pit that lets the water soak away. Needs soil that drains. |
| Sump pit and pump | Where gravity will not do it. Adds a pump and a power supply to the job. |
There is a fourth option that is not on this list because it is prohibited nearly everywhere: the sanitary sewer. Clean groundwater in a foul sewer is a recognised cause of overflows, and connections found later can be ordered disconnected at the owner’s expense.
Line items
Quantities are per foot of drain except where noted. Restoration differs by type: reseeding a lawn is not the same job as repouring a basement slab.
| Line item | Unit | Material | Equipment / hr | Trade | Data |
|---|---|---|---|---|---|
| Machine excavation (conditional)length ÷ 25 ft/hour for yard drains, ÷ 8 for footing drains (modelled) | hour | — | $57 – $110 | Operating Engineers and Other Construction Equipment Operators | sourced |
| Break out and remove the slab (conditional)full length, on interior drains | linear ft | $9.00 – $22 | — | — | estimated±42% |
| Re-pour the slab (conditional)full length, on interior drains | linear ft | $11 – $26 | — | — | estimated±41% |
| Perforated drainage pipefull run length | linear ft | $1.40 – $3.60 | — | — | estimated±44% |
| Washed drainage stone, deliveredtrench volume × 0.6 fill ÷ 27 × 1.4 tons/CY | ton | $28 – $68 | — | — | estimated±42% |
| Geotextile filter fabriclength × trench width × 3 to line the trench | sq ft | $0.11 – $0.28 | — | — | estimated±44% |
| Catch basins and grates (conditional)one per surface inlet | each | $55 – $190 | — | — | estimated±55% |
| Daylight outlet and headwall (conditional)1 where the outlet daylights | lot | $90 – $300 | — | — | estimated±54% |
| Dry well (conditional)1 where the outlet is a dry well | lot | $420 – $1,400 | — | — | estimated±54% |
| Sump pit, pump and discharge (conditional)1 where the outlet needs a pump | lot | $430 – $1,200 | — | — | estimated±47% |
| Labourer: lay pipe, place stone, backfill6 h + 0.14 h/ft, doubled to 0.28 on interior drains (modelled) | hour | — | — | Construction Laborers | sourced |
| Topsoil and seed over the trench (conditional)length × trench width × 2.2 for access, on outdoor drains | sq ft | $0.28 – $0.85 | — | — | estimated±50% |
The reasoning behind each figure
Written out so a drainage contractor can point at the exact assumption that is wrong. A number with no reasoning behind it cannot be corrected.
- Machine excavation
- Machine rates are FEMA cost codes 8280 and 8572, which exclude the operator, so operator hours are added from BLS wage data instead of being hidden inside the rate.
- Yard drains are shallow and fast, around 25 feet per machine-hour. Exterior footing drains are deep and slow, around 8, because the trench has to reach the footing and be battered back for safety.
- Interior drains use no machine at all: that work is on the slab line below.
- Break out and remove the slabestimated, ±42%
- Saw cutting and breaking out a strip of basement floor, then carrying it out by hand up the stairs. There is no machine access, which is why this is priced per foot rather than by the hour.
- This single line is why an interior drain costs several times a yard drain of the same length.
- Re-pour the slabestimated, ±41%
- Concrete, placing and finishing the strip back. The new concrete will not match the old, which is worth knowing before it happens in a finished basement.
- Priced per foot of the strip that was opened.
- Perforated drainage pipeestimated, ±44%
- Corrugated HDPE at the bottom of the band, rigid PVC with a sock at the top. Commodity product, identical nationwide.
- Rigid pipe is worth the difference under a driveway or anywhere the trench will be loaded.
- Washed drainage stone, deliveredestimated, ±42%
- Bulk aggregate: the rock is cheap and the haul is not, so distance to the quarry decides the delivered price. Same band as the septic and sewer datasets, and for the same reason.
- Quantity from the trench geometry of the chosen type, at 1.4 tons per cubic yard, filling roughly 60% of the trench depth.
- Geotextile filter fabricestimated, ±44%
- Wraps the stone so soil cannot migrate into it. A French drain without fabric silts up and stops working, usually within a few years, and there is no way to fix it short of digging it up again.
- Sized to line the trench, so roughly three times the trench width per foot of run.
- Catch basins and gratesestimated, ±55%
- Surface inlets that let standing water enter the drain directly rather than soaking down to it. Useful where there is a low spot that ponds.
- Each one needs a sediment sump underneath or it becomes a way of filling the pipe with silt.
- Daylight outlet and headwallestimated, ±54%
- Where the ground falls away far enough, the drain simply ends in the open with a grate and a small headwall to stop the bank eroding. The cheapest outlet by a long way.
- Dry wellestimated, ±54%
- A buried pit of stone or chambers that lets the collected water soak away. Needs soil that actually drains, which is worth testing first: a dry well in clay is an expensive hole that fills up and stays full.
- The band reflects size, which follows how much water the drain collects.
- Sump pit, pump and dischargeestimated, ±47%
- Where gravity will not carry the water anywhere useful, it has to be pumped. That adds a pit, a pump, a discharge line and a power supply, and it turns a passive system into one that can fail.
- Interior perimeter drains almost always end this way, which is part of why they cost more.
- Labourer: lay pipe, place stone, backfill
- Scales with length and with how awkward the work is. An interior drain is all hand work in a confined space, so it carries roughly double the hours per foot of a yard drain.
- Metro-adjusted wage from official BLS data; the hours per foot are our estimate.
- Topsoil and seed over the trenchestimated, ±50%
- Restoration to a rough lawn over the disturbed strip, which is wider than the trench because of machine access.
- Interior drains have no lawn to restore, which is one of the few things in their favour.
Not included in this dataset
- Permit fees
- Many jurisdictions regulate where collected water may be discharged, and some require a permit. Fees vary with no national source and are excluded rather than averaged.
- Waterproofing the foundation wall
- An exterior footing drain is often installed at the same time as a membrane or coating on the wall, because the wall is already exposed. That is separate work and is priced by the square foot of wall, not the foot of trench.
- Rock, roots and buried utilities
- Any of them changes excavation cost several times over and none is knowable from a postcode. Have the utilities located before anyone digs; that call is free in most of the country.
- Landscaping and hard surfaces
- This covers topsoil and seed over the trench. Replacing a driveway, patio, planting or irrigation that the trench crossed is not included.
- Whether you need one at all
- Water in a basement is often a grading or gutter problem, and both are far cheaper to fix. A drain that treats a symptom will keep treating it.
Use the calculator to price your own run, or read the full method.