French Drain Cost Calculator

In 2026, a French drain typically costs $25 to $65 per linear foot installed, so a common 100-linear-foot run lands roughly between $2,500 and $6,500, and larger or more complex projects scale up from there. A French drain is a gravel-filled trench with a perforated pipe that collects and redirects water away from where it's pooling — a yard, a foundation, or a basement. The cost depends mostly on the drain type: a yard or surface drain is the cheapest (around $25 per linear foot) because it's shallow, an exterior foundation perimeter drain is mid-range (around $50 per linear foot) because the trench is deeper alongside the footing, and an interior basement drain is the most expensive (around $65 per linear foot) because it requires breaking up and re-pouring the concrete slab and usually tying into a sump pump. Trench depth and soil also matter — a deep, footing-level trench costs more than a shallow one, and digging through dense clay or rocky ground adds 15% to 35%. Add-ons like a sump pump and basin, a catch basin, a daylight outlet, sod or landscape restoration, concrete repair, and permits add to the total. This calculator lets you set the length, type, depth, and soil to estimate your French drain. Pricing varies by region, accessibility, and contractor.

A French drain is a simple but effective drainage system: a trench dug at a slight downhill slope, lined with landscape fabric, partly filled with gravel, fitted with a perforated pipe, then covered with more gravel (and sometimes soil or sod). Water in the surrounding soil takes the path of least resistance — it seeps through the gravel, enters the perforated pipe through the holes, and flows by gravity along the pipe to a discharge point well away from the problem area (a lower spot in the yard, a storm drain, a dry well, or a daylight outlet on a slope). The name comes from Henry French, a 19th-century lawyer and farmer who popularized the design, not from France. French drains solve a range of water problems: a soggy or standing-water section of lawn (a yard drain), water collecting against a house's foundation and seeping into the basement or crawl space (an exterior perimeter drain), or water already getting into a basement (an interior under-slab drain tied to a sump pump that pumps it back out). The key to a working French drain is proper slope (typically a fall of about an inch per 10 feet so water flows), adequate gravel and fabric to keep soil from clogging the pipe, and a good discharge point. This calculator estimates installation cost; the right type depends on where your water problem is.

Interior and exterior French drains both manage water around a home but are installed very differently and target different problems. An exterior (foundation perimeter) French drain is dug outside, in the ground alongside the foundation footing — a trench is excavated down to the footing level, a perforated pipe and gravel are installed, and the goal is to intercept groundwater before it ever reaches and pressures the foundation wall, keeping the basement or crawl space dry from the outside. It's effective and addresses the source, but it requires significant excavation around the house (and disturbing landscaping, walkways, or decks), so it's labor-intensive, and at around $50 per linear foot it's mid-range. An interior French drain is installed inside the basement — a channel is cut into the concrete slab around the perimeter of the basement floor, a perforated pipe and gravel are placed in it, and the drain collects water that's coming up through or under the slab and routes it to a sump pit, where a sump pump lifts it out and away from the house. It's the most expensive type (around $65 per linear foot) because it involves jackhammering and re-pouring concrete and usually adding a sump pump, but it's often the practical choice for an existing finished home because it doesn't require digging up the whole yard. In short: exterior stops water outside (more excavation, addresses the source), interior manages water that's already getting in (concrete work plus a sump pump). A waterproofing contractor can advise which fits your situation; this calculator prices all three types.

Whether you need a sump pump depends on whether the drain can discharge by gravity or has to pump water uphill. A French drain works by gravity — water flows downhill through the pipe to an exit point. If your property has enough slope, the drain can simply 'daylight' (open to the surface) at a lower spot, or tie into a storm drain or dry well, and no pump is needed; this is common for yard drains and many exterior perimeter drains on sloped lots. A sump pump becomes necessary when there's nowhere lower for the water to flow to on its own — most notably with interior basement drains, where the basement floor is below the surrounding ground and water collected by the drain must be lifted up and out. In that case the French drain routes water to a sump pit (a basin in the floor), and the sump pump automatically switches on when the water rises and pumps it through a discharge line away from the house. A flat lot with an exterior drain that can't reach a lower outlet may also need a pump. The sump pump (and basin) is a significant add-on — roughly $1,200 installed in this calculator — and for reliability in areas with frequent outages or heavy water, people often add a battery backup or a second pump. So: gravity-only (daylight or storm-drain outlet) needs no pump and is cheaper; below-grade interior drains and flat lots typically require a sump pump. This calculator lets you add a sump pump and basin, plus a daylight outlet or catch basin, depending on your discharge setup.

The bulk of a French drain's cost is excavation — digging the trench — so anything that makes digging slower, deeper, or harder raises the price. Soil type is a big factor: standard, loamy, easy-to-dig soil is the baseline, but dense clay is heavier, stickier, and slower to excavate (adding roughly 15%), and rocky, gravelly, or hardpan ground is the worst, sometimes requiring special equipment or breaking up rock, which can add around 35% or more. If tree roots, hidden utilities, or buried obstacles are in the path, digging slows further. Trench depth multiplies the work too: a shallow surface trench for a yard drain moves relatively little soil and is cheaper (about -15%), while a deep, footing-level trench for a foundation perimeter drain moves far more material, may need shoring or sloped sides for safety, and takes much longer to dig and backfill (adding about 25%). Deeper trenches also mean more gravel and more soil to haul away or relocate. Access matters as well — a tight backyard a machine can't reach may require hand-digging, which is dramatically more labor. Because the trench is the heart of the job, the combination of how deep you must go and how hard the ground is to dig drives a large part of the total, which is why this calculator adjusts the per-foot rate for both depth and soil. A contractor will assess your soil and the required depth on site.

A simple, shallow yard French drain is a feasible DIY project for a handy homeowner, but the more serious foundation and basement drains are usually best left to professionals. A basic surface or yard drain — a shallow gravel-filled trench with a perforated pipe to move standing water from a soggy lawn area to a lower spot — can be done DIY if you're willing to do the heavy digging, get the slope right (about an inch of fall per 10 feet so water actually flows), use landscape fabric and proper gravel to keep the pipe from clogging, and have a valid downhill discharge point. The main challenges are the physical labor of digging, achieving consistent slope, and avoiding buried utilities (always call 811 to have lines marked first). Where DIY gets risky is with exterior foundation drains and interior basement drains: exterior drains require deep excavation against the foundation (deep trenches can be dangerous and can undermine the footing if done wrong), and interior drains require cutting and re-pouring concrete and integrating a sump pump — mistakes here can worsen water problems, damage the foundation, or fail to actually keep the basement dry. Improper slope, inadequate gravel/fabric, or a bad discharge point are common DIY failures that lead to a drain that clogs or doesn't work. Given that water intrusion can cause expensive foundation and mold damage, the foundation and basement types are generally worth hiring an experienced drainage or waterproofing contractor. This calculator estimates professional installation cost; for a small yard drain you could use it as a benchmark against doing it yourself.

A well-installed French drain typically lasts about 30 to 40 years, and sometimes longer, but its lifespan and performance depend heavily on the installation quality and some occasional maintenance. The most common reason French drains fail early is clogging — over time, fine soil, silt, and roots can work their way into the gravel and the perforated pipe, restricting or blocking the flow of water. Good installation greatly extends life: wrapping the pipe and/or lining the trench with quality landscape (filter) fabric keeps soil out, using clean, properly sized gravel maintains flow paths, and keeping the right slope ensures water keeps moving rather than sitting and depositing sediment. Maintenance is modest but helpful: periodically check and clear the discharge outlet (a daylight exit or catch basin can get blocked by debris, leaves, or critters), keep the area over the drain free of anything that would compact it or send roots into it (avoid planting trees or shrubs with aggressive roots right over the line), and if flow seems reduced, the pipe can sometimes be flushed or snaked out. Adding a catch basin or cleanouts at the surface makes future cleaning much easier, which is why those are popular add-ons. If a French drain does eventually clog badly, sections may need to be dug up and the gravel/pipe replaced. Interior drains tied to a sump pump also require maintaining the pump (testing it, and replacing it every 7-10 years or so). Overall, a quality French drain is a long-lasting, low-maintenance solution as long as it's built with fabric and good gravel, has clear outlets, and gets the occasional check. This calculator estimates installation; investing in fabric, a catch basin, and proper slope pays off in longevity.

Most French drain installations take from one day to about a week, depending on the length of the run, the drain type, the depth, the soil, and the site access. A short, simple yard or surface drain — a shallow trench of modest length in easy-to-dig soil with a machine that can reach the area — can often be completed in a single day, sometimes two. An exterior foundation perimeter drain takes longer, frequently a few days to a week, because the trench is deeper and must run around part or all of the house, the excavation is more involved, and landscaping or hardscaping may need to be removed and restored. An interior basement drain also commonly takes several days to a week because the crew has to break up the concrete slab around the basement perimeter, dig the channel, install the pipe and gravel, set the sump pit and pump, and then re-pour the concrete (which then needs time to cure). Factors that stretch the timeline include long runs (more linear footage), hard digging conditions (dense clay or rocky ground slow excavation significantly), poor access (a backyard a machine can't reach may require slower hand-digging), wet weather, and the extent of restoration needed afterward (replacing sod, landscaping, walkways, or concrete). Add-ons like a sump pump, catch basins, and outlets add some time. Your contractor can give a specific schedule after assessing the length, type, depth, soil, and access of your project. This calculator estimates the cost; the timeline depends on these same factors plus weather.