Standing water in a North Texas yard is rarely solved by spreading more dirt over the low spot. Runoff, compacted soil, roof water, and a poorly defined outlet can keep the same area saturated after each heavy rain. A thoughtful drainage plan starts by tracing where water comes from, where it should go, and which materials can keep that path open.
French drain installation uses a gravel-filled trench with a perforated or slotted pipe to collect water along the drain’s length, rather than at one surface point. It may help intercept slope runoff or move water away from saturated areas, but trench dimensions, pipe size, grade, and outlet must match the property and project conditions. NDS explains the basic system components.
For homeowners, contractors, and builders in Van Alstyne, Anna, and nearby communities, the first decision is not which rock looks best. It is whether the yard needs a subsurface collection system and how the site should be graded to support it.
Use McCraw’s area calculator to start planning your drainage material quantities.
What Is a French Drain, and When Does a North Texas Yard Need One?
Short answer: A French drain is a gravel-filled trench with a perforated or slotted pipe that collects water along the length of the trench and directs it toward a suitable outlet. It may help when a North Texas yard stays saturated, receives runoff from higher ground, or collects water near a driveway, building, or other feature. It is not a universal fix, and the right layout depends on the property’s grade, soil, water volume, and outlet.
How a French drain moves water
Unlike a point drain that collects water at one grate, a French drain provides a collection path below the surface. Water can enter through the surrounding gravel and perforations in the pipe, then travel through the pipe toward the planned discharge point. The typical assembly includes geotextile fabric, perforated pipe, and clean drainage gravel. The fabric separates soil from the gravel so fine material is less likely to fill the open spaces that water needs to pass through. NDS explains the difference between French drains and surface drains, while Washington State University Extension outlines how fabric, pipe, and gravel work together in a subsurface drainage system.
Signs your yard may need subsurface drainage
Look for standing water that remains after rain, persistently soft or saturated areas. Water flowing across a slope, or runoff that repeatedly reaches a foundation, driveway, or planting bed. A French drain can intercept slope runoff or help collect water connected to gutters and buried downspouts. The LSU AgCenter describes French drains as a way to evacuate water from saturated areas.
In Van Alstyne, Anna, and surrounding North Texas communities, a drainage problem may be influenced by local grading, compacted construction soil, heavy rainfall, or changes made during landscaping. First determine where the water starts, where it needs to go, and whether a surface grading correction could solve the issue more simply. If water is near a foundation, retaining wall, easement, utility, or neighboring property, get site-specific advice before excavation. McCraw can help with material questions, but it does not provide engineering or guaranteed drainage designs.
How Deep and Wide Should a French Drain Trench Be?
Short answer: A common planning range is about 12 to 18 inches wide and 18 to 24 inches deep, but those dimensions are not a universal prescription. The right trench depends on how much water must be collected, the soil, the outlet, nearby utilities, and what will be built or driven over the drain.
For a straightforward residential drainage problem, published guidance describes French drain depths from roughly 8 inches to 2 feet. The NDS French drain guide notes that smaller problems may use a trench only 5 to 6 inches wide, while larger water volumes call for more width. Those narrower dimensions may not provide enough room for the pipe and a durable layer of clean drainage rock in every installation.
What changes the trench dimensions?
Start with the water problem rather than a preset measurement. A trench collecting a small wet area may need less capacity than one intercepting runoff from a slope. A roof drainage route, or a long stretch of saturated soil. Clay-heavy or compacted soil can also change how quickly water reaches the pipe. The outlet matters just as much: a deeper trench is not useful if the system cannot maintain a continuous fall toward a stable discharge point.
Width must leave practical room for the pipe, surrounding rock, and separation fabric. A wider rock envelope can provide more void space for water, while a narrow excavation may be difficult to install and protect without disturbing the pipe. The LSU AgCenter’s installation guidance describes a 12- to 18-inch-wide, 18- to 24-inch-deep trench as a common example, with a perforated pipe at the base and washed gravel around it. Treat that example as a starting point for planning, not a guaranteed design for every North Texas yard.
When should you get professional input?
Get qualified drainage or engineering input when the trench will run beside a foundation, retaining wall, basement or crawl space, public drainage feature, easement, or neighboring property. These situations can involve structural loads, groundwater, erosion, or discharge rules that a basic yard drain plan may not address. Professional review is also sensible when the outlet is unclear, the site stays saturated, or the project requires substantial excavation. Before digging any trench, have underground utilities located through the appropriate 811 service.
Which Pipe, Fabric, and Drainage Rock Work Together?
A dependable drainage assembly is more than a trench filled with whatever rock is available. The pipe gives collected water a path, the fabric separates soil from the aggregate, and clean drainage rock leaves open spaces for water to move around the pipe. Washington State University Extension describes this combination as geotextile fabric, perforated pipe, and surrounding gravel. The fabric helps keep soil from filling the voids between the stones, which helps preserve drainage capacity over time.
For many residential applications, a 4-inch perforated pipe is a common planning reference. Heavier saturation or larger water volumes may require a different diameter, so pipe selection should follow the site conditions rather than a one-size-fits-all rule. The pipe belongs in the drainage zone, with the rock providing a free-flowing envelope around it. Follow the pipe manufacturer’s instructions for connections, perforation orientation, fittings, and any transition to solid outlet pipe.
| Material | Role in the system | Selection guidance |
|---|---|---|
| Perforated pipe | Collects water entering through the surrounding rock and carries it toward the planned outlet. | A 4-inch pipe is commonly described for residential work, but saturated sites may call for a larger diameter. |
| Geotextile fabric | Separates native soil from the rock so fine material does not quickly fill the drainage spaces. | Line the trench and leave enough material to wrap over the completed rock layer where the design calls for an enclosed drain. |
| Clean drainage rock | Surrounds the pipe and provides open pathways for water to reach the perforations. | Washed gravel around 1 inch is one published planning example. Confirm the required gradation for the project. |
| Fill sand or decorative material | May serve grading, leveling, or visual purposes, but should not automatically be treated as drainage aggregate. | Fill sand is non-structural and contains sand, dirt, and small rock. Decorative rock may be selected for appearance, not void space or drainage performance. |
That distinction matters in North Texas, where a material that looks suitable at the surface may not perform the same way below grade. Fill sand can be useful for general grading, leveling, low areas, or backfilling, but it is not a substitute for engineered drainage aggregate. Decorative rock is also not automatically interchangeable with clean drainage rock. Review the available rock options for drainage before choosing between river rock and crushed stone, and confirm product suitability for the trench design.
McCraw supplies rock, gravel, sand, and soil for projects in Van Alstyne, Anna, and surrounding North Texas communities. Because exact material suitability and availability depend on the project, bring the trench dimensions, pipe plan, and intended use when asking about materials. A supplier can help clarify material options, but site-specific drainage design near foundations, utilities, easements, or neighboring properties may require a qualified drainage professional or engineer.
What Slope and Outlet Should the Drainage Plan Include?
Short answer: Plan a continuous fall toward a stable outlet, but do not assume one slope works for every property. The correct grade depends on the trench length, pipe type, soil, expected water volume, receiving area, and local drainage requirements. A French drain installation that moves water efficiently but releases it onto a neighbor’s lot or an eroding slope has only relocated the problem.
Use grade references as a starting point
Published guidance gives useful planning ranges, not a universal specification. Washington State University Extension describes a trench slope of 0.5% to 1%, while the LSU AgCenter gives 1% to 2% as a general drainage rule. NDS also notes that a French drain should generally drop at least 1% over 100 feet, with some corrugated-pipe guidance calling for a 2% minimum. A 1% grade equals a one-foot elevation change over 100 feet, but a short residential run may need a different calculation to reach its intended outlet.
Before digging, mark both ends and check the grade along the full route. Avoid low spots that create standing water inside the trench. Guidance from Penn State’s constructed underdrain bulletin emphasizes maintaining continuous fall toward the outlet. If the property cannot provide that fall, a site-specific drainage professional may need to evaluate another route or system.
Make the outlet stable and neighbor-safe
Discharge should reach a stable surface area, approved drainage feature, or other location that can accept the flow without washing out soil. Protect the outlet from erosion with appropriate stabilization for the site, and inspect whether water could cross a sidewalk, driveway, easement, public right of way, or neighboring property. Local codes, HOA rules, municipal requirements, and stormwater restrictions may affect where concentrated water can be released. Confirm those requirements before construction rather than treating the lowest point on the lot as automatically acceptable.
Where spreading the flow is appropriate. WSU Extension describes using a T-shaped pipe at the end of a French drain to slow discharge and distribute it over a larger area. That approach still needs adequate receiving ground. Keep the outlet accessible for inspection, and check it periodically for obstructions so water continues to flow freely. Near foundations, retaining walls, groundwater, utilities, or property boundaries, get qualified guidance before finalizing the grade and outlet location.
For North Texas homes and job sites, practical planning means measuring the route, confirming the fall, and resolving the discharge point before ordering pipe and drainage rock. A contractor can then match the material plan to the actual site instead of forcing the site to fit a generic slope.
Washington State University Extension drainage guidance, LSU AgCenter French drain guidance, and Penn State’s constructed underdrain bulletin provide the cited grade, outlet, and discharge references.
What Are the Steps for French Drain Installation?
French drain installation should follow the water, the grade, and the planned outlet, not simply the easiest line to dig. The sequence below is a practical planning guide for a smaller residential project. Soil type, runoff volume, utilities, property lines, and the final discharge point can change the right design and materials.
- Map the water and outlet. Observe where water collects, where it enters the area, and where it could safely discharge. Trace roof runoff, slope runoff, and saturated spots. The outlet should lead to a stable location where water will not undermine a foundation, driveway, retaining wall, or neighboring property. A French drain works best when it has a continuous fall toward that outlet. The Washington State University Extension drainage guidance explains how French drains can intercept runoff and route it around site features.
- Call 811 before excavation. Contact 811 or use the official 811 service information for your state before breaking ground. Wait for utility markings and keep the planned trench clear of marked lines. Do not assume a shallow trench is automatically safe, especially near irrigation, electrical, gas, water, or communications lines.
- Mark the grade. Lay out the trench with stakes and string, then check the intended fall from the collection area to the outlet. Published guidance gives different slope ranges for different systems, so treat them as planning references rather than a universal specification. If the site cannot provide a dependable outlet or grade, stop and get professional advice before digging.
- Excavate the trench. Dig to the planned width and depth while keeping the bottom reasonably smooth and continuously descending. Stockpile usable topsoil separately from unsuitable spoil. Follow safe excavation practices, keep people and equipment away from unstable trench edges, and do not enter a trench that may collapse or contain an unmarked hazard.
- Place the geotextile fabric. Line the trench with drainage fabric, leaving enough material on both sides to fold over the finished stone. Fabric separates surrounding soil from the aggregate, helping preserve the open spaces that carry water. Avoid tearing it during placement.
- Set the perforated pipe. Place the perforated pipe on the prepared trench base and align it with the planned outlet. A four-inch pipe is described as suitable for many residential applications, but heavier saturation or larger water volumes may require a different size. Confirm pipe orientation, fittings, and the solid outlet connection for the specific system.
- Add clean drainage rock. Surround the pipe with clean, free-draining aggregate rather than soil-rich fill. The LSU AgCenter describes washed gravel as typical material around the pipe in its French drain installation guidance. Material selection should match the design and site conditions.
- Wrap and backfill. Fold the remaining fabric over the rock so soil cannot readily migrate into the drainage layer. Backfill in a way that does not crush, shift, or sharply bend the pipe, then restore the surface with appropriate soil or finish material. Keep heavy equipment off the completed drain because compaction can damage the pipe and reduce water flow.
- Protect and inspect the outlet. Secure the outlet against clogging, erosion, and accidental crushing. A stable discharge point matters as much as the trench. Inspect it after significant rain and remove obstructions so water can flow freely.
Bring in a drainage contractor or engineer before construction when the trench will run near a foundation, retaining wall, easement, public drainage feature, groundwater, or major utility. Professional input is also appropriate when runoff could affect neighbors, the outlet is uncertain, or the project involves substantial excavation or structural risk. McCraw Landscape Supply can help with material-selection and quantity questions, but it does not engineer or install site-specific drainage systems.
How Much Gravel Does a French Drain Need, and How Is It Maintained?
Material planning starts with the trench, not the truck. As a broad planning reference, LSU AgCenter estimates about one cubic yard of gravel for every 10 linear feet of French drain. That figure is not a universal order quantity. Your actual need changes with trench width and depth, the diameter of the pipe. The amount of gravel below and above the pipe, and the shape of the route.
Measure the planned trench in sections if it changes dimensions or direction. Then account for the space occupied by the pipe before converting the remaining trench volume to gravel. Clean, washed drainage gravel is commonly used around the pipe, but the suitable aggregate depends on the design and site conditions. McCraw can help you think through material selection, but a drainage professional should address site-specific engineering questions.
For a more focused material estimate, use McCraw’s estimate your gravel needs guide. You can also use the area calculator to organize measurements and plan quantities. Enter the length, width, and depth as accurately as possible, and keep your trench measurements available when you ask about aggregate. If the layout includes multiple trench sizes, calculate each section separately rather than relying on one average.
Keep the outlet open
Maintenance is usually centered on the outlet. Check it periodically for leaves, sediment, soil, animal nesting, or other obstructions, and confirm that water can flow freely after significant rain. A blocked outlet can make a properly built system appear to fail. Keep heavy equipment and other traffic off the drain where possible, since compaction or crushing can damage the pipe and restrict flow. Also inspect the discharge area for new erosion or signs that water is backing up, especially after changes to grading or nearby construction.
Use McCraw’s calculators to plan your gravel quantity, then contact the team with your measurements and material questions.
Frequently Asked Questions
How much will it cost to install a French drain?
Cost depends on trench length and dimensions, excavation conditions, pipe, fabric, drainage rock, equipment, labor, and the outlet. Material quantity is not a flat allowance: LSU AgCenter gives about 1 cubic yard of gravel per 10 linear feet as a planning estimate. But actual needs vary with the trench and rock depth (LSU AgCenter guidance). Measure the route first, then estimate each material separately rather than relying on an unverified per-foot price.
Can I install my own French drain?
A homeowner may be able to handle a small, straightforward project with suitable tools and careful layout. Call 811 before digging, establish a continuous fall to a stable outlet, and keep soil out of the clean drainage rock with geotextile fabric. Get professional or engineering input near foundations, retaining walls, utilities, easements, groundwater, or public drainage, or when discharge could affect a neighboring property.
How deep does a French drain need to go?
There is no universal depth. LSU describes a common trench of 18 to 24 inches deep and 12 to 18 inches wide. While NDS notes that many water-diversion projects fall between about 8 inches and 2 feet deep (LSU AgCenter guidance; NDS guidance). Choose dimensions based on water volume, soil, utilities, surface use, pipe, and the planned outlet, not a standard number alone.
What are the downsides of a French drain?
A French drain requires excavation, enough grade for water to reach a suitable outlet, and correct material selection. It can underperform if soil fills the rock, the pipe is crushed, the outlet is blocked, or the system sits in groundwater. Heavy equipment can compact soil and damage the pipe, so keep traffic off the completed drain and periodically check that the outlet remains open and flowing.
Plan Your Drainage Materials with McCraw
Accurate material planning can help you order the right amount of drainage rock and avoid preventable changes during a North Texas project. Use McCraw’s area calculator to estimate your material quantities, then contact McCraw with questions about selecting products or planning bulk delivery. Share your trench dimensions, rock needs, and project conditions so the conversation starts with useful details.
