How to Build a French Drain with Crushed Limestone: A Pro's Guide from South Texas
If you’ve ever watched your yard turn into a lake after a good South Texas rain, you’ve probably thought, "There’s got to be a better way." And you’re right. Building a French drain is one of the most effective ways to redirect water and save your yard, driveway, or foundation from standing water or erosion.
And here’s a pro tip from us locals: crushed limestone is the unsung hero of a good French drain. It’s affordable, drains like a champ, and compacts well while staying loose enough to let water move. Let’s walk through how to build a simple French drain that actually works—and why limestone rock makes all the difference.
What Is a French Drain?
A French drain is a trench filled with gravel or crushed rock (and usually a perforated pipe) that redirects water away from problem areas. Think of it as an underground gutter system that handles runoff like a boss.
Whether you're protecting your foundation, clearing a soggy lawn, or draining a driveway, it’s one of the simplest and most cost-effective solutions.
Personal Tip: I installed my first French drain after my dog's play area turned into a muddy pit every time it rained. After just one weekend and a few yards of crushed limestone, we went from swamp to solid ground—and my dog hasn’t tracked mud into the house since.
Why Crushed Limestone Is Perfect for the Job
Here in San Antonio and South Texas, we deal with everything from clay-heavy soil to flash flooding. That’s where crushed limestone shines:
Superior Drainage: The angular shape allows for great water flow between the gaps.
Local & Affordable: It's readily available in our region (and yep, we haul it!)
Strong Support: It holds its shape, so your trench won’t collapse over time.
Neutral Appearance: It blends well with most landscapes if left exposed.
Looking for the right size? #57 limestone rock (3/4" to 1") is the most common pick for a French drain. It’s coarse enough to prevent clogging but allows plenty of flow.
Quick Tip: Don’t use pea gravel or round river rock for drainage—it tends to compact and slow water down.
Step-by-Step: How to Build a French Drain with Crushed Limestone
1. Plan the Drain Path
Walk your yard after a rain. Where does the water pool? Where do you want it to go? Draw a simple plan. Aim for a slight slope (about 1 inch per 10 feet) so gravity does the heavy lifting.
Pro Story: A customer in Elmendorf called us after heavy rain flooded her carport. She thought she needed concrete work, but we suggested a French drain first. Problem solved with a few tons of limestone and a weekend of digging.
2. Gather Your Materials
You don’t need fancy tools—just a strong back and the right materials:
Shovel or trenching tool
Landscape fabric
Perforated drain pipe (4" flexible is common)
Crushed limestone (#57 rock)
Gravel rake (optional)
Wheelbarrow or cart
Spray paint or string (for layout)
3. Dig Your Trench
Go at least 6" wide and 18" deep for most residential projects. Make sure the trench slopes away from the problem area.
Pro Tip: If you’re going across a lawn, consider renting a trenching machine—your back will thank you.
4. Line It with Landscape Fabric
This prevents weeds and keeps silt from clogging your rock. Overlap the fabric on the sides—you’ll fold it back over at the end.
5. Add a Base Layer of Limestone
Pour in a few inches of crushed limestone rock as a base. This cushions the pipe and boosts drainage. Level it out with your rake.
6. Lay the Perforated Pipe
Holes down! Trust us, this allows water to rise and enter the pipe while keeping silt out.
7. Fill with More Limestone
Fill the trench nearly to the top with #57 crushed limestone. Then wrap the remaining fabric over the top.
Bonus Tip: Leave the rock exposed if you're going for a decorative look, or cover it with topsoil and sod to blend it into your yard.
8. Direct the Outflow
Where does the pipe end? Make sure it drains into a safe area—like a dry creek bed, ditch, or gravel pit. You can even install a pop-up emitter to help it drain discreetly.
Common Mistakes to Avoid
❌ Using the Wrong Rock
Sand or round gravel can compact and trap water—stick with angular crushed limestone.
❌ Not Enough Slope
Without a proper slope, water will sit in the trench. Use a level and measure grade.
❌ No Fabric
Skipping the fabric means faster clogging and shorter lifespan. It’s worth the small extra cost.
Need Crushed Limestone Delivered in San Antonio?
You guessed it—we’ve got the good stuff. At Shady Oaks Express, we haul bulk crushed limestone, #57 rock, and other drainage materials all across San Antonio, Elmendorf, Pleasanton, and South Texas. Whether you need a few yards or a full truckload, we’re ready to help you dig, drain, and dry out your property.
Personal Note: We’ve delivered to every kind of project—muddy front yards, carports that flood, new home builds, and even a ranch trail that used to wash out every spring. If it involves rock and water, we’ve seen it—and we’ve got a solution.
👉 Request a Quote or give us a call at 210-842-1440.
Want to Learn More?
Check out our other expert guides:
Shady Oaks Express – We Move Earth to Bring You Heaven.
