Installing a French drain means digging a sloped trench, lining it with filter fabric, adding washed gravel, setting perforated pipe, and backfilling so water flows to a lower outlet. The steps are simple. The reason so many drains quit working after two seasons is that three of them get rushed, and in East Texas clay, rushing any one turns a drain into a buried trench full of mud.
How to Install a French Drain: The 7 Steps
- Find the water. Track where it collects, where it comes from, and where it can go.
- Call 811. Utilities get marked before a blade touches dirt.
- Dig the trench. Typically 18 to 24 inches deep, 12 inches wide, sloped toward the outlet.
- Line it with fabric. Geotextile lines the trench walls and floor, not the pipe.
- Bed the gravel. Two to three inches of washed rock under the pipe.
- Set the pipe. Perforated 4-inch pipe, holes down, laid to the slope.
- Cover and backfill. More gravel, fold the fabric closed, then topsoil or sod.
That list matches most guides online. Here’s where the jobs actually go wrong, based on the installs our crews get called out to fix.
Step 1: Find the Water Before You Pick the Line
Most failed drains we’re called to inspect were dug where the water pools, not where it comes from. Those are often different spots. Surface water pools at the low point. Subsurface water travels along the top of a clay layer and surfaces wherever that layer pinches out.
Walk the yard during a hard rain, not after it. A yard that stays soggy a week later has a subsurface problem, and a shallow surface trench won’t touch it. The Texas A&M AgriLife Extension guide to installing drainage systems is a solid primer on why some soils need help draining at all.
Did you know? Some yards don’t need a drain. If the ground slopes back toward the house, regrading the surface costs less than a drain, and we’ll say so on the estimate rather than sell you pipe you don’t need.
Step 2: Call 811 First, Every Time
Question: Do you have to call 811 before installing a French drain? Answer: Yes. Texas law requires anyone disturbing the ground to notify a one-call center at least two working days before digging, under the Underground Facility Damage Prevention and Safety Act.
The Texas One-Call Law sits in Chapter 251 of the Texas Utilities Code, and a two-foot trench across a yard is exactly what it covers. Irrigation lines, invisible fence, propane runs, and septic laterals aren’t marked by 811, so walk those separately.
Step 3: The Slope Number Nobody Measures
A French drain needs a minimum fall of 1%, about 1 inch of drop per 8 feet of run. Below that, water sits in the pipe. Standing water in clay soil lets silt settle and build up, and a silted pipe is a dead pipe.
This is the most skipped step on DIY installs. A trench that looks level to the eye is usually off by an inch or two over 40 feet. We run a laser level on every trench and check it again after the gravel base goes in, because gravel compacts unevenly. Our full guide to French drains covers how depth and slope change by drain type.
Pro Tip: Measure the total fall between your wet spot and your outlet before deciding where the drain goes. If you don’t have enough drop, the answer isn’t a longer trench. It’s a sump basin or a regraded swale.
Step 4: Fabric Lines the Trench, Not the Pipe
Here’s where we break from what most big-box guides tell you. Sock pipe — perforated pipe pre-wrapped in a fabric sleeve — is sold as a shortcut, and in Blackland Prairie clay it’s the fastest way to a clogged drain.
Clay fines work into that sleeve and stay there. Once the sock blinds over, water can’t reach the perforations at all, and there’s no cleaning it without digging the whole run back up. We’ve pulled sock pipe out of five-year-old installs packed solid with gray clay.
The alternative takes ten extra minutes: line the trench walls and floor with geotextile fabric, fill with clean washed gravel, set bare perforated pipe in it, then fold the fabric over before backfilling. The fabric filters at the soil boundary, where filtering belongs. The gravel stays clean and the pipe stays open.
Step 5: Holes Down, and Why That’s Still Argued About
Ask ten contractors which way perforations should face and you’ll get a real split. The case for holes up is that gravity carries water in from above. The case for holes down is that water enters the trench from the bottom as the water table rises, and downward holes let the pipe empty completely instead of holding a standing inch.
We lay ours holes down in clay for a reason specific to this soil. Blackland Prairie clay drains so slowly that the trench works like a reservoir filling from the bottom up. Holes down means the pipe starts moving water at the lowest possible level and drains dry between rains instead of staying wet and collecting silt.
In sandy, fast-draining soil the argument matters less. Check what you have through the USDA’s Web Soil Survey, which maps soil down to the parcel level for most Texas counties.
Step 6: The Outlet Is the Whole Job
A French drain doesn’t make water disappear. It moves water from one place to another, so the outlet decides whether the system works.
Daylight is best: the pipe exits on a slope below the drain and gravity does the rest. Flat properties often don’t have that, and the fallback is a pop-up emitter, a dry well, or a tie-in to an existing culvert or roadside ditch. What you can’t do is end the pipe in a hole dug in clay. That’s a bathtub with a lid on it, and it’s the second most common failure we find.
When the trench crosses a driveway or runs long through hard ground, we bring in excavation equipment instead of a walk-behind trencher to hold the slope consistent over the full run.
What Goes Wrong on DIY Installs
| Mistake | What happens | The fix |
| No measured slope | Water stands in the pipe, silt settles | Laser or string level, 1% minimum |
| Sock pipe in clay | Fabric sleeve blinds over in 2–5 years | Fabric-lined trench, bare pipe, washed gravel |
| Unwashed gravel | Rock dust cements into the voids | Specify washed drainage rock |
| Outlet dug into clay | Drain fills and stays full | Daylight, emitter, or ditch tie-in |
| Drain placed at the puddle | Misses the actual water path | Diagnose during rain, not after |
Pro Tip: If you’re hiring this out, ask two questions: what slope are you setting, and where does the water go? A specific answer to both screens contractors better than any online review.
Get the Slope and the Outlet Right the First Time
A French drain is simple to describe and unforgiving to install. The trench, fabric, and gravel are straightforward. Slope, pipe orientation, and the outlet are where a working system separates from an expensive buried trench, and clay soil punishes every shortcut on those three.
If your yard holds water days after a rain, get a proper diagnosis before anyone digs. 4W Land Management is a family-run operation in Kerens serving Navarro, Henderson, Freestone, and Ellis Counties, and we walk every property before we quote a property drainage solution. Request your free on-site drainage assessment and we’ll show you where your water is going and what it takes to move it. Military, veteran, and first responder discounts are available.
Frequently Asked Questions
How deep should a French drain be? Most yard drains run 18 to 24 inches deep and about 12 inches wide. Foundation and basement drains go deeper, down to the footing level. Depth depends on where the water travels, not a fixed rule.
What is the correct slope for a French drain? A minimum 1% fall, roughly 1 inch of drop per 8 feet of run. Less than that and water sits long enough for silt to settle and clog the pipe. More slope is fine if the outlet stays lower.
Can I install a French drain myself? You can, and plenty of homeowners do it successfully on short runs with good fall. The three things that sink DIY installs are unmeasured slope, sock pipe in clay soil, and an outlet with nowhere to drain.
Does a French drain work in clay soil? Yes, but the design has to account for slow-draining soil. That means clean washed gravel, geotextile at the soil boundary rather than wrapped on the pipe, and an outlet that actually carries water away instead of holding it.