How to Install a French Drain in Your Yard (Step-by-Step with Equipment Guide)

By the team at Beehive Rental & Sales — Serving Southern Utah's contractors and homeowners since 1994.

A French drain is one of the simplest and most effective ways to solve yard drainage problems. It is nothing more than a gravel-filled trench with a perforated pipe that collects subsurface water and directs it to a safe discharge point.

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Quick Answer: A French drain requires a trench 18-24 inches deep with a minimum 1% slope toward the discharge point, lined with landscape fabric, filled with drain gravel, and fitted with a 4-inch perforated pipe. A walk-behind trencher from BeeHive Rental & Sales in St. George cuts the trench in hours instead of days of hand digging. Call (435) 628-6663 for trencher availability and project advice.

Key Takeaways

• •A walk-behind trencher cuts installation time by 75% — a 50-foot French drain that takes a full weekend to hand-dig takes 2-3 hours with a trencher
• •Slope is critical: minimum 1% grade (1 inch of fall per 8 feet of run) or water will sit in the pipe instead of draining
• •Always call 811 before trenching — hitting a buried gas line turns a weekend project into a disaster
• •Southern Utah's clay-heavy desert soil creates drainage problems — caliche layers trap water
• •Browse trenching and drainage equipment at BeeHive — trenchers, plate compactors, laser levels available

What Is a French Drain and How Does It Work?

A French drain consists of three components:

1. •A trench dug along the path where you want to redirect water
2. •Perforated pipe that collects water through small holes along its length
3. •Drain gravel surrounding the pipe that filters soil particles while allowing water to flow freely

Landscape fabric wrapped around the gravel prevents fine soil particles from migrating into the gravel over time.

When You Need a French Drain

• •Standing water in your yard that persists more than 24 hours after rain
• •Water pooling against your foundation despite proper surface grading
• •Soggy, mushy areas in your lawn that never seem to dry out
• •Basement or crawl space moisture coming through walls or floor
• •Retaining wall backfill drainage to prevent hydrostatic pressure buildup

Equipment You'll Need

Trencher (Walk-Behind or Ride-On)

The most important piece of rental equipment. A walk-behind trencher cuts a 4-6 inch wide trench to depths of 24-36 inches in a fraction of the time it takes to dig by hand.

Walk-behind trencher: Ideal for residential French drains up to 50 feet. Ride-on trencher: For drains over 50 feet or in very hard soil.

Plate Compactor

After backfilling the trench, a plate compactor settles the material to prevent future settling that would create a visible depression.

Laser Level

Slope is everything. A laser level lets you set your trench depth at the starting point and verify consistent slope along the entire run before you lay pipe.

Materials List (for 50-foot run)

• •4-inch perforated drain pipe — Rigid PVC preferred
• •Landscape fabric — Heavy-duty, non-woven, drainage-rated
• •3/4-inch clean drain gravel — ~1 cubic yard per 10 linear feet = 5 cubic yards total
• •Pipe fittings — End caps, couplers, elbows as needed
• •Drain grate or pop-up emitter — For the discharge end

Order materials before your rental day.

Step-by-Step: Installing Your French Drain

Step 1: Plan Your Route and Slope

• •Starting point: Where water collects
• •End point: Where water will discharge
• •Slope: Minimum 1% grade — 1 inch of fall per 8 feet. For a 50-foot drain, discharge end must be at least 6 inches lower than the starting end.

Step 2: Call 811 for Utility Locates

Call at least 48 hours before your planned trenching date. Required by Utah law and required by common sense.

Step 3: Mark Your Trench Path

Use stakes and string line, then spray paint the ground. Verify slope with the laser level before trenching.

Step 4: Trench

Trench dimensions: 18-24 inches deep, 9-12 inches wide.

Trenching tips:

• •Keep the trencher moving at a steady pace
• •Check depth every 10 feet
• •Southern Utah: Caliche layers at 12-18 inches will slow the trencher — reduce forward speed and let the cutting chain work

Step 5: Verify Slope

Before any pipe or gravel goes in, verify slope. Set up the laser level and confirm the trench bottom drops at least 1 inch per 8 feet along the entire run. Flat spots = standing water in the pipe = failure.

Step 6: Line the Trench with Landscape Fabric

Roll fabric along the bottom and up both sides, leaving enough excess to fold over and overlap at the top later.

Step 7: Add Base Gravel and Place Pipe

1. •Shovel 2-3 inches of clean drain gravel into the trench bottom
2. •Lay perforated pipe on top with perforations facing DOWN
3. •Connect pipe sections with couplers
4. •Ensure pipe follows the slope of the trench

Holes facing down is correct — the pipe collects water that rises up from the gravel beneath it.

Step 8: Backfill with Gravel

Fill around and over the pipe with clean drain gravel to within 4-6 inches of the ground surface. For a 50-foot drain, this is 5 cubic yards of gravel (~7-8 tons). Use the wheelbarrow.

Step 9: Wrap the Fabric and Backfill

Fold the excess landscape fabric over the top of the gravel, overlapping edges by at least 6 inches. Fill the remaining 4-6 inches with native soil or topsoil.

Step 10: Compact and Finish

Run the plate compactor along the backfilled trench. Seed or sod to prevent erosion.

Critical Slope Calculation

Preferred slope: 2% grade = 1 inch per 4 feet. More forgiving of minor installation errors.

Southern Utah Drainage Considerations

Caliche Layers: Caliche prevents water from percolating downward. French drains provide the path that caliche blocks naturally.

Monsoon Season: Southern Utah's monsoon season (July-September) delivers intense, short-duration storms that dump large volumes of water in minutes. A properly sized French drain handles normal rainfall, but monsoon deluges can temporarily overwhelm any residential system.

New Construction Drainage: Many newer subdivisions have drainage problems from heavy equipment compacting soil during construction, creating an artificial impermeable layer. BeeHive Rental & Sales sees a steady stream of new-subdivision homeowners renting trenchers for exactly this reason.

Cost Comparison: DIY vs. Hiring Out

FAQ

How deep should a French drain be?

A residential French drain should be 18-24 inches deep. If protecting a basement or crawl space, it should reach to the level of the foundation footing.

How long does a French drain last?

A properly installed French drain with landscape fabric, clean gravel, and quality pipe will last 20-30 years or more.

Can I install a French drain without a trencher?

You can dig by hand. For a 50-foot drain at 18 inches deep, expect 8-16 hours of digging in Southern Utah's rocky, compacted soil. A trencher rental from BeeHive cuts the trenching to 2-3 hours.

Do I need a permit for a French drain in St. George?

Standard residential French drains typically do not require a permit. Contact St. George at (435) 627-4830 if your drain discharges into a public storm drain or crosses property lines.

Ready to fix your drainage problem? BeeHive Rental & Sales in St. George has trenchers, plate compactors, laser levels, and all the equipment you need for a French drain installation. Call (435) 628-6663 for availability, or browse the equipment inventory to start planning.