Installing a french drain gives standing water a clear path away from your home and foundation. The basic process involves digging a sloped trench, lining the soil with landscape fabric, adding gravel, and installing a perforated pipe.
You can tackle a 25-foot drain over a single weekend for about $528 in materials. If you want to skip the heavy digging, a pro charges $250 to $1,875.
If you decide to go the expert route, Lawn Love easily connects you with vetted local pros who can handle the job for you.
| Key takeaways |
|---|
| • Call 811 before you dig—every time, no exceptions. • The trench needs at least a 1% slope (1-inch drop per 8 horizontal feet) for gravity to move the water. • Pipe holes face down—this reduces clogging from the stone and soil layer above. • A properly installed french drain lasts 30–40 years; skipping the landscape fabric wrap typically means digging again within a few years. |
1. Gather the materials
Before you dig, collect everything you need. Here’s the full list for a standard exterior French drain:
Materials:
- Perforated drain pipe (4-inch diameter)
- Non-perforated pipe
- Pipe connectors (for runs over 100 feet)
- Pipe plug / end cap
- Underground drainage tape OR PVC cement
- Nonwoven landscape or filter fabric (4–6 oz.)
- Washed round gravel, 1/2 to 1 inch diameter
Tools:
- Shovel, trencher, or mini excavator
- Drill (if your pipe doesn’t come pre-perforated)
- Leveling tools
- Rake
- String line
- Spray paint, flags, or stakes
- Sod cutter (Optional)
- High-pressure water hose (Optional)
2. Choose your endpoints
The drain should begin in the wet area or slightly uphill from it so it can intercept water before it collects and pools. Choose an exit point that sits lower than the starting point so water can keep moving downhill through the pipe.
Choose your endpoint based on your yard, soil, and local rules, but never discharge water onto a neighbor’s yard or public sidewalk — it violates municipal codes.
| Option | How it works | Best for |
| Dry well | Moves surface water underground to absorb slowly | Properties experiencing moderate runoff lacking nearby curbs |
| Pop-up emitter | Lets water out at the end of the pipe when the pipe fills with water | Yards with enough slope to carry water away from the house |
| Rain garden | Planted basin filters runoff as it sinks into the soil | Properties seeking ecological benefits and visual upgrades |
| Daylighting | The pipe empties above ground at a lower spot, using a grate to block pests | Sloped yards that drain into woods or ditches |
Pro tip: Mark the full path from start to exit with spray paint, flags, or stakes before you dig.
Note: If your yard becomes swampy when it hasn’t been raining, you may have a broken pipe rather than a drainage problem. Investigate before you dig.
Read more: Reasons Why Your Yard is Flooding
3. Mark the route
Once you have chosen your starting point and exit point, mark the full drain path with bright spray paint, flags, or stakes. Keep the route as direct as possible while still allowing the pipe to slope steadily downhill toward the outlet.
Kevin Thompson, owner of Sylvan Scapes in Staunton, VA, says you should “reroute around major structural roots and hand dig a narrower trench section so you are not severing the roots that keep a mature tree stable.”
Note: Calling the free 811 hotline before you dig is mandatory. It takes just minutes to locate underground utility lines, saving you from dangerous and expensive mistakes.
Warning: If your yard stays soggy even when it has not rained, investigate first. Constant wetness can point to a broken pipe or another drainage issue rather than simple surface runoff.
4. Dig the trench
Digging is the hardest part of this project, so bribe a friend to help (pizza and drinks usually work). Start by laying a heavy-duty tarp to catch the excavated dirt and use a sod cutter to safely remove the grass for later. Keep heavy equipment away from the edges to avoid cave-ins.
Trench dimensions and digging:
Dig your trench 9-12 inches wide and at least 18 inches deep. If you run into dense clay or roots, Andrew Day, owner of Advanced Quality Lawn in Akron, Ohio, recommends loosening the soil with a high-pressure hose.
Nail the slope:
- To ensure water flows, you must maintain a 1 percent downward grade (a 1-inch drop every 8 feet).
- “For a foolproof 1% slope DIY method, I tell people to use a rotary laser level (I’ve used a DEWALT DW074K on job sites) plus a grade rod and spray paint ‘target depths’ every 4 feet in the trench,” Thompson says.
- After setting your starting depth, Thompson recommends calculating your subsequent marks so you can “paint those depths on the trench wall, and dig to the paint.”
- If you lack a laser level, Thompson says a 50-foot clear vinyl water level and marked stakes will achieve the same result.
Alternative tip: To navigate uneven trenches, Day suggests pulling a tight string line between your end stakes and verifying the drop every 8 feet with a 4-foot carpenter’s level.
Note: Don’t stress over perfect dirt slopes; you can fine-tune with gravel later. Remove sharp rocks and tamp the dirt smooth so the landscape fabric lies flat.
5. Line the trench with landscape fabric
To stop dirt and roots from destroying your system, you must line your trench. Always use a 4-to-6-ounce nonwoven drainage fabric — woven fabrics trap water, while nonwoven options let it flow freely while blocking sediment.
Thompson warns that without fabric, a trench running through silty topsoil can turn mushy and fail within 12-24 months. “Repair is basically a do-over,” Thompson says.
“Cut the sod wider than you think, excavate the contaminated stone, regrade the trench bottom, then rebuild with nonwoven like Mirafi 160N and clean stone — spot-cleaning almost never buys you real time.”
How to install landscape fabric:
- Lay enough fabric to cover the bottom and both sides of the trench (Note: If joining 2 rolls, overlap the ends by 12–18 inches, shingled in the direction of water flow).
- Push the material flat against the bottom and the dirt walls, ensuring it is pressed fully into the bottom corners so the weight of the gravel doesn’t stretch or tear it.
- Leave about 10-12 inches of extra fabric hanging over both top edges. (You will fold these over the gravel later to create a fully enclosed “burrito wrap.”)
- Pin the fabric to the dirt walls using metal garden staples to keep it from slipping when you pour the stone.
6. Fill with gravel
To ensure clean water flow and prevent clogs, use the correct stone. Avoid pea gravel (which restricts flow) and unwashed stone (which introduces dirt that clogs the fabric).
What to do:
- Purchase washed gravel or washed crushed stone (like #57 stone) that is 3/4-inch to 1.5 inches in size.
- Shovel a 3-inch layer of this clean stone onto the fabric at the bottom of the trench.
- Rake the gravel smooth.
- Double-check your slope with a level to ensure the gravel bed still flows downhill. This layer will serve as the level base for your perforated pipe in the next step.
How much gravel do you need?
Buy enough gravel for the entire trench at once, including the base, sides, and top cover. Multiply the trench’s length x width x total depth (in feet) to find the total volume.
Example: A 30-foot drain that is 1 foot wide and 1.5 feet (18 inches) deep:
- 30 x 1 x 1.5 = 45 cubic feet of total volume (Ordering extra is safer than subtracting for the 4-inch pipe).
- 45 cubic feet x 96 = 4,320 pounds. (Suppliers sell by the ton or cubic yard, so ask for 2.1 tons or 1.6 cubic yards.)
7. Add the pipe
To handle heavy rain and prevent clogs, use a 4-inch diameter pipe (either pre-perforated or drilled yourself every 2 inches). Lay it directly on the gravel bed with the holes facing down.
“Down matters because the pipe is supposed to collect from the stone bed at the bottom and keep the trench from saturating,” Thompson says. If the holes face up, he explains the pipe just acts like a gutter, letting grit fall in and failing to drain until the trench is completely waterlogged.
What to do:
- Install a plug at the highest point to prevent dirt and gravel from clogging the line.
- Center the pipe on your 3-inch gravel base so water flows freely underneath.
- Connect segments tightly using underground drainage tape (for corrugated pipe) or PVC cement (for rigid) to block tree roots.
- Switch to a non-perforated pipe when routing toward the discharge point so collected water doesn’t leak back into the yard.
Which pipe should you use? Use flexible corrugated pipe for easy installation in standard yards, or durable, crush-resistant rigid PVC for straight, high-traffic areas like driveways.
8. Cover the pipe
You must wrap the pipe and gravel completely to protect the system from soil intrusion. Professional landscapers call this the burrito wrap method. If you skip this step, dirt will mix with the gravel and ruin your hard work.
What to do:
- Pour more washed gravel over the top and down the sides of the pipe.
- Stop adding gravel when you are about 3 inches below the top of the trench.
- Fold the extra landscape fabric over the top of the gravel layer.
- Overlap the two fabric edges so the rocks are completely enclosed.
9. Add finishing touches
The underground work is completely finished. You can now make the surface blend into your existing landscape design.
What to do:
- Crushed rock or gravel surface — simple, low-maintenance, clearly defined.
- Dry stream bed — crushed rock plus larger decorative stones of mixed shapes and sizes; looks like a natural drainage channel.
- Hidden under sod — 3 inches of gravel, then landscape fabric, then topsoil, then sod. If you saved the grass with a sod cutter in Step 4, reinstall it now.
Note: Keep surface plantings far away from the drainage area if your system runs near a septic tank.
Read more: Tips to Help Your Lawn Recover from Flooding
French drain installation cost
Materials for a 25-foot DIY French drain cost about $528 (roughly $21 per linear foot), though owning basic tools can reduce this price.
On the other hand, professional installation ranges from $10 to $75 per linear foot, bringing the total for a 25-foot project to anywhere between $250 and $1,875.
While DIY is often cheaper upfront, a professionally installed system lasts 30-40 years and guarantees safe results. We recommend hiring an expert to avoid severe property damage from common DIY mistakes.
Warning: Without experience, it is easy to grade the pipe incorrectly, choose materials that cause clogs, or accidentally flood your neighbor’s yard.
FAQs
Simply clear debris once a year with a rented electric sewer snake (best with a helper). Well-built systems need no other maintenance for the first 10 years.
Not directly, as heavy rain can overwhelm and clog the system. Instead, install a catch basin between them to handle water surges and collect leaf debris for easy cleaning.
Hire a local drainage pro
French drains take a weekend of hard work to install, and the digging can leave your grass looking rough. Once your new system is in place, Lawn Love makes lawn recovery easy. Get an instant quote and let a vetted local pro handle maintaining your yard after installing a French drain.
Main Image: Rock-lined french drainage channel in lawn. Image Credit: Shutterstock
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