Trench volume, perforated pipe, washed stone, fabric and outlet for a yard or foundation drain.
Estimates are planning aids, not a professional quote. Double-check quantities and product coverage — and any local code or permit requirements — before you buy.
⚠ Call 811 before digging, and route the outlet so it discharges onto your own property or an approved drainage easement — not onto a neighbor's yard or a public sidewalk.
| Drainage | $247–$334 |
| Membrane & Fabric | $82–$110 |
| Soil & Fill | $14–$18 |
| Total | $342–$463 |
Excludes tools, delivery, tax and permit fees. Labor not included — this is a DIY materials estimate.
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About this calculator
Give the French Drain Builder a trench length, depth and slope and it lays out a complete subsurface drainage run: the washed stone that fills the trench, the perforated pipe and its filter sock, the non-woven fabric that wraps the whole assembly, and an outlet — daylighting downhill, a pop-up emitter, or a dry well — plus a catch basin if you need a surface inlet.
It carries your slope through the whole run, so the trench comes out deeper at the outlet end than at the start, the way a real one has to be dug. Open advanced options to set pipe diameter, whether it's socked, the fall percentage, direction-change fittings and a waste allowance.
Step by step
A step-by-step walkthrough to go with your plan above. Follow the product instructions and any local code or permit requirements as you work.
Watch the problem area during or right after rain to find where water is actually coming from, and route the trench to intercept it on the uphill side, running to the lowest usable outlet on the property.
Have utilities located before digging, then mark the trench line with paint or stakes and string, confirming the outlet point is genuinely lower than the start.
Excavate to width and depth, checking your fall with a line level or laser every few feet — aim for at least 1% (⅛ in/ft) continuously downhill with no low spots where the pipe could dip back uphill.
Lay non-woven filter fabric into the trench with enough overlap on both sides to fold back over the top later — this envelope is what keeps the stone from silting shut.
Add a couple inches of drainage stone, lay the perforated pipe on top (perforations down for groundwater, up if you're mainly chasing surface flow), and connect any fittings at direction changes.
Cover the pipe with the remaining drainage stone, then fold the fabric flaps back over the top so the entire stone bed is wrapped.
Daylight the pipe past the low end with a rodent guard, install the pop-up emitter flush with grade, or tie into the dry well chamber — whichever the site called for.
Backfill with topsoil and restore turf over the fabric, or leave the top course of stone exposed as a finished drainage swale, then keep the outlet clear of mulch and debris.
Equip the job
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Keep planning
Garden & Yard
Answers
A French drain is a gravel-filled trench with a perforated pipe at the bottom that intercepts water moving through the soil and carries it away to a lower point before it can pool against a foundation, drown a low spot in the yard, or keep a planting bed waterlogged. It's the right tool for chronic wet-soil problems, not for a one-time storm — if the yard only floods in the worst storms of the year, surface grading or a catch basin tied to solid pipe may be enough on its own.
Most residential French drains run 12–24 inches deep and 6–12 inches wide, deep enough to sit below the frost line and intercept the water table or seepage layer causing the problem, and wide enough to fit the pipe with a few inches of stone on every side. Foundation-perimeter drains typically go deeper, down near the footing. This calculator's default of 18 inches deep and 9 inches wide fits a typical yard drain; go deeper if you're chasing water that's pooling well below the surface.
Plan on at least 1% fall — about ⅛ inch of drop per foot of run — from the high end down to the outlet, and never let the pipe dip back uphill anywhere along the way or water stalls right there and the pipe can freeze or clog. On a long run that adds up: 60 feet at 1% drops about 7 inches end to end, which is why this calculator digs the outlet end noticeably deeper than the start.
Daylighting — running the pipe out to open air at a point lower than the start — is the simplest and cheapest option whenever the property actually has a lower point to send water to. A pop-up emitter is the fix when the discharge point is nearly flat: it opens under flow and closes the rest of the time so it doesn't just sit open as a mulch-clogged hole. A dry well (an underground gravel or chamber reservoir) is for sites with no usable low point at all, and only works if the soil percolates reasonably well — it's the option of last resort, not first choice.
Bare perforated pipe works at first, but in anything but coarse, well-draining soil, fine particles slowly wash through the stone and into the perforations over several seasons, silting the pipe closed from the inside where you can't see it happening. A knitted filter sock over the pipe — or a fully sealed non-woven fabric envelope around the whole stone bed — is inexpensive relative to digging the trench back up in five years, and most experienced installers treat it as standard, not optional.
A drain meant to catch water before it reaches the foundation typically runs along the foundation itself, tied into the footing drain if one exists, but any drain daylighting or discharging near the house needs to carry water away from it, not toward it — the outlet should end up lower than and pointed away from the foundation. Keep new trenching a safe distance from the foundation footing itself to avoid undermining it, and call 811 first since utility laterals often run in exactly this zone.