Oklahoma City has been Installing French Drains for a long time. We started in 1993 so that makes 2024 our 31st year. We have installed French Drains in Oklahoma City, Moore, Yukon and Mustang, not to mention virtually every other town in Central or Western Oklahoma.
Still many people incorrectly mistake a “Surface Drain,” for a “French Drain.” They are not the same thing.
This is not a French Drain!
The Picture Below is Not a French Drain Either.
Channel Drains are one type of Surface Drain. A Surface Drain Is any type of drain that takes water in the top (Surface). They have a Grate on top.
Below is a picture of a Surface Drain that many people will tend to call a “French Drain.”
Surface Drain connected to a Transition Pipe
A French Drain is a Perforated Drain Pipe with thousands of small holes in it. It is placed in the bottom of a Drainage Trench that has been dug by the installer of the French Drain. It should be placed on top of a Trench Liner which is placed first in the Drainage Trench.
The French Drain Pipe has a cloth filter around the pipe as well.
French drain Installation
with trench liner and pipe filter
Once this is done correctly, The trench is filled with gravel of some type. We use Crushed 67 grade Lime Stone. The empty space from the top of the pipe to ground level is filled. THE DEPTH OF EVERY FRENCH DRAIN TRENCH VARIES. What Determines the depth can depend on several things. But for now just know that some French Drains are Shallow while others are Deep. The Deeper the Drainage Trench, the more gravel it takes to fill it.
In the Picture above you can see the water stains on the concrete. Water has been standing there a long time to make those types of stains. Eventually the grass will completely grow over the lime stone gravel. Note! Dirt should never be placed on top of a French Drain. In sunny areas, grass will put out runners and grow over the limestone gravel. Once covered it creates a Natural Filter called a Thatch Filter. The French Drain continues to work great and you don’t even know its there.
I have installed French Drains all the way back to 1993 that still work great with no maintenance.
In the picture above, you can see that the grass is growing over the French Drain more slowly in the shaded area by the trash cans. This can be sped up by sprinkling grass seed directly into the gravel.
French Drains in Full or Partial Shade, can be decorated instead of letting grass grow over them.
