What Is A French Drain?

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The basic concept of a French drain is simple, and it is a great solution for anyone who needs to keep water away from the foundation of their home. Many people could probably not identify a French drain by name alone, but chances are you have seen these drainage systems on multiple occasions. Do you ever notice the opening of a tube or PVC pipe peeking up from underneath a lawn? Have you seen a trail of gravel or stones leading away from someone’s house and out to the street? If so, you were likely seeing highly beneficial French drains!

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How French Drains Work

Both French drains and other types of drains work to disperse water, but French drains have a unique focus on water accumulated under the surface of your lawn. French drains are subsurface drainage systems that focus on diverting water away from a building or structure. This is accomplished by laying a perforated pipe or tube under the soil surface and encasing it in a permeable substance, such as gravel.

The pipe or tube allows groundwater to enter through the perforations and leads the water out to a city sewer system or disperses the water evenly throughout your lawn. The gravel works to collect water that gets introduced to your lawn, which helps optimize the water flow to the underground drainage pipe.

Accumulated groundwater can cause mold to form around your home’s foundation, invite termites, result in flooding of your yard and house, and a host of other detrimental effects to your property. Standing or pooling water frequently occupying space in your yard is an indication of poor drainage, but there are less obvious signs to look out for that also suggest drainage problems on your property. If your lawn constantly feels damp, or if the foundation/ground floor of your home is experiencing mildew and excess moisture, then your yard may benefit greatly from installing a French drain.

Components Of French Drains

The individual parts that make up a French drain system are simple tools, but the system as a whole is one of the more complex drainage systems offered by Oliviers. However, if you do need the advantages of a French drain, the benefits your property will receive are invaluable! Below is a list of the basic components of a French drain system.

Landscape Fabric

Once a trench is dug, landscape fabric is the first part of the system to install. The fabric lines the bottom of the trench, and its main purpose is to prevent dirt and particles from clogging your drain pipe. For this reason, a permeable, non-woven geotextile fabric is the best choice for optimal filtration and water flow.

Black Landscape Fabric


Some people or companies may use sand as backfill material, but sand absorbs moisture and is less effective for draining water. At Oliviers, we use a clean, round gravel that will provide the best water collection and drainage for your new French drain system. The gravel is placed on top of the landscape filter fabric, as well as all around the pipe that runs through the trench.

Gravel For A French Drain

Perforated Pipe

Also known as “weeping tile,” perforated pipes are the main component of French drain systems. Water that collects and trickles down through the gravel will flow into a slotted pipe at the bottom of the trench. As groundwater rises, it will fall into the holes in the pipe and be carried away from areas of standing water or excess moisture.

Black Perforated Pipe

How To Install A French Drain

If you are about to install a French drain in your yard, there are several factors to consider before a shovel ever touches your turf. For example, it is important to know where gas lines, sprinkler systems, and other subterranean utility lines are located on your property. Luckily, the pros at Oliviers are experienced and know how to make this identification process as simple as possible.

Another important factor to consider is where the greatest need is for your drainage system. Whether you are concerned about groundwater damaging your home’s foundation or if you have pools of water on your lawn after rainfall, we will help you make sure that your French drain runs along the most beneficial path in order to keep your home safe and dry. French drains are very helpful and commonly used for the following situations:

  • Keeping foundations strong and dry
  • Improving drainage and health of lawns
  • Protecting hardscape areas from flooding, such as patios and walkways  
  • Allowing landscapes with retaining walls to drain
  • Keeping floors (and basements, where applicable) free from mildew

Once you have determined where you want to start your French drain, the following steps will be taken to install your new drainage system.

  • Find The Path: The whole point of French drains is to let gravity do all the work! We will find/create the perfect slope for your drain, making sure that the drain opening, if applicable, does not face any neighboring properties. Your drain can either flow to a designated area, such as the municipal sewer system in the street, or it can be designed to evenly disperse water throughout your lawn.

  • Dig: The trench will be dug on a downward slope between 1 to 2 feet underneath the surface of your lawn, and it should be no wider than 12 inches. The slope of the trench should decline at a rate of 1 inch for every 10 feet of pipe that is planned to be laid. This rate of decline is optimal for steady and even water flow to occur naturally.

  • Lay Down Landscape Fabric: When initially laying down a landscape fabric, the base of the entire trench will be lined in order to provide filtration for the rest of the system. There needs to be a good amount of fabric hanging off both sides of the trench before the pipe is laid down. The fabric from the sides of the trench will be used to wrap around the gravel and perforated pipe later.

  • First Installation Of Gravel: The next step is to evenly disperse gravel over the lined trench. This first layer of gravel will serve as bedding for the pipe.

  • Lay Perforated Pipe: The different segments of pipe used will be connected and placed into the trench. The pipe will be placed directly onto the previously installed layer of gravel, which will help add stability to the placement of the pipe. It is extremely important to make sure the perforations (holes) in the pipe are facing down when the pipe is laid. If the holes are facing up, the groundwater will be allowed to rise before it drains into the holes, essentially defeating the purpose of the French drain.

  • Second Installation Of Gravel: After the pipe is firmly positioned within the trench, we will apply a second layer of gravel overtop the pipe. With the pipe now encased in gravel, it can be wrapped up in the excess landscape fabric in what is commonly known as “burrito style.”

  • Covering The Trench: Some people prefer to fill the trench and encased pipe with soil for reseeding, but the traditional look would feature larger gravel/rounded rocks filling the remainder of the trench. Decorative and functional rocks create a conducive environment for proper drainage, and the clear path they create will always help you locate your drainage system.

  • Maintenance: Once the finished French drain system is up and running, occasional maintenance will be required. Clogs and backups may occur that will need attention. When this happens, it is much more beneficial to have rocks instead of grass because the source of the problem will be easier to identify and access. Perform routine inspections to ensure all is flowing smoothly.