A French drain is a gravel-filled trench with a pipe that carries water away from an area where it collects. The gravel you choose matters, and KK Ranch Stone & Gravel carries the three types most often used.

Most French drains today use slotted pipe, filter fabric, and gravel. Older systems lacked these essential components, leading to clogs from accumulated soil and sand over time.

Many builders prefer using perforated drainage pipes with long, narrow slits rather than small round holes, because slots reduce the amount of fine soil particles that can enter the system.

Best Types of Gravel for French Drains

The gravel used in your French drain is one of the most important choices in the project. Below are three materials available at KK Ranch Stone & Gravel:

Pea Gravel
Pea gravel is a common choice for French drains due to its smooth, rounded texture and small size. Pea gravel leaves open space between stones for water to move through.

Washed Rock
Washed rock has been thoroughly cleaned to remove fine particles that can cause clogs. This clean, angular aggregate allows water to pass through freely, which is why it is a common choice for French drains.

Septic Rock
Also known as leach rock or drainage rock, Septic rock is naturally porous and made up of mixed-size stones. Its mix of sizes leaves gaps for water to move through.

How a French Drain Is Typically Built

1. Dig a trench alongside your foundation at least 2 feet wide. Depth may vary—up to 6 feet for basements, or as shallow as 2 feet for slab-on-grade homes.
   
   
2. Place the slotted drainage pipe directly on undisturbed soil, sloping it away from the home to encourage gravity-assisted drainage.
   
   
3. Cover the pipe with a minimum of 12 inches of washed rock.
   
   
4. Lay filter fabric over the gravel to prevent soil infiltration and clogging.
   
   
5. Backfill the trench with topsoil and compact it to original grade level.

Every site is different. Soil type, slope, and where the water needs to go all affect how a drain should be designed, so for drains near a foundation, talk with a drainage contractor first. KK Ranch Stone & Gravel supplies and delivers the gravel; we do not design or install drains.

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French Drain FAQs

Do French drains work in Texas soil?
They are widely used in Johnson County, where clay soil can hold water. How well one works depends on its design and how it is built.

Can I install a French drain myself?
Yes, you can — with proper planning and the right materials like slotted pipe, filter fabric, and clean gravel. It’s important to slope the pipe correctly and use high-quality aggregates. 

What’s the difference between washed rock and septic rock?
Washed rock is thoroughly cleaned to remove fine particles that can clog your drainage system. Septic rock, on the other hand, is a mix of porous, variable-sized stones designed to allow water to pass through easily. Both are common choices for French drains. Call us at (817) 558-1966 to talk through which fits your project.