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What Is A French Drain And How Does It Work?

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A French Drain installation requires when your lawn is almost permanently wet, and it is needed when it rains heavily, water stands on the ground, and pushes underground table for raising. A French drain helps to pass away excess water from the low spot area of the land. However, in this content, you can get a full picture of what is a French drain and how does it work.

What Is A French Drain And How Does It Work?

French Drain

What Is A French Drain?

A pipe that collects excess water from the ground’s low spots and redirects water to a specific downhill area is called French Drain.
A perforated pipe wide diameter is placed in the ground to collect excess water and drain it away from the ground’s affected areas. We cover the pipe with a fabric filter, gravels, or rock so that it is not visible. And the pipe will be angled to ensure downward the drainage is smooth. As French Drain being less open, it lets the water drain away to the far area for less damage.

Why is it called a french drain? The history of french drain

Henry Flagg French is the designer French Drain system. Being from New England, and was a gentleman farmer, he loved farming and was fascinated by agriculture. He realized that a good farm’s land was becoming abolished due to heavy water, and good drainage could add value. The French also believed that diseases were by wet areas and the farmland’s unhealthy vapors. Similarly, Henry Flagg French thought that a damp basement could affect you to become sick.

Henry Flagg French described later about different types of drainage systems like

  1. The Deanstone System.
  2. The Keythorpe System.
  3. Wharncliffe System etc.

He also calculated the various pipes with different diameters to release water, and he evaluated the pros and cons of the various mentioned pipe styles. Drainage solutions are here.

Henry Flagg French suggested something, and it helped many people who had been suffering from the disaster of rains. An open channel fills up with gravels and a perforated pipe, which delivers water from the ground surface. It was known as “Cellar Drain” to Henry Flagg French, and we call it “French Drain.”

Henry Flagg French died in 1885, and his youngest son did not follow his drainage system, but his younger issue Daniel Chester French who followed his father and gave the French drain method to the people. He installed a French drain around the Statue of Lincoln’s site in the Lincoln Memorial to water away from the foundation in 1994.

The exciting thing is that some people thought that the French drain was named after France’s people. But it was after Henry Flagg French. Once, he lived in a house in 137, East Capitol St.

How Does A French drain Work?

Water always follows the rule to flow away to the lowest point and the straight forward way and moves the loose soil into the empty areas, where a French drain comes in.
The French Drain delivers a relaxed passage for the water for flowing over and done with it. Water goes to the Drain or channel, which filled up with gravels, then the water goes into the perforated pipe at the bottom of the channel. Water runs through the tube freely, and release a safe distance from the home foundation.

The bottom of the Drain will be sloped 1 inch for every 8 feet to flow water smoothly. The water can be distributed to the followings, depending on the situation of the ground area:

  • To the street
  • To a dry well
  • To a low-lying area of your asset
  • To a drainage ditch

It should be wise to install a French drain near your home, where water can pool, mostly water can sit there for hours or days, even after heavy rainfall.

French Drain Installation


Step-1: Choose a location for a channel or drain where you want.
Step-2: Get approval for installing French Drain.
Step-3: Measure or calculate slope.
Step-4: Dig the channel or drain.
Step-5: Use fabric filter to the line of the Drain.
Step-6: Fill your Drain with gravels.

Required Tools and Materials

You need the following tools and stuff to install a French drain. Here goes the list for your quick collection.

Tools & equipment:

  • Line Level.
  • Square spade.
  • Shovel.
  • Mason’s line.
  • Hammer.
  • Bow rake.
  • Tape measure.
  • Knife.

Required materials:

  • Fabric and Garden Staples.
  • Fabric filter.
  • Wood stakes.
  • Gravels.

Now, everything is ready to install the French Drain.

Installation Procedure of French Drain

Here, we are describing the installation procedure below with steps:

Step-1: Choose Location for Channel or Drain You Like:

Select the French Drain’s root and location, considering your yard spots where water lies. Now, you have to confirm where to flow water, where the top and bottom, and exit and end will be located of the French Drain.

Step-2: Get Approval for Installing French Drain:

Obtain approval first before installing your French Drain, because the yard drainage will not affect any negativity to any public area or any body’s property legally. Talk to your local law authority regarding this issue to not fall into trouble in the future.

Step-3: Measure or Calculate About the Slope:

You have to ensure the French Drain’s slope to flow away water to the down into the perfect area. The bottom of the Drain will slope 1 inch for every 8 feet.
If you have a sharp slope in your yard, this is alright. But, the sharpness speeds up the flow of the water to flow in exiting.
To ensure accurate sloping, you have to tie both the starting and last point, then do the following:

  • Tie tightly one stake with mason’s line.
  • Run the mason line to another stake and tie it loosely.
  • Attach line level with line.
  • Unfasten the loose end of the line.
  • Tightly drag the line.
  • To level, tune the line.
  • Knot the line with stake firmly.

Now, check and be ensured about the slope than has been created correctly. If necessary, adjust the depth of the channel as well.

Step-4: Digging your Channel or Drain:

Dig the soil with the shovel where necessary according to the plan. Channel or Drain should be deep enough to meet the need. Be careful about the bottom of the channel will compact and smooth.

Step-5: Apply Fabric Filter to the Line of the Drain:

Use surface fabric when you have completed the digging channel on the ground. After putting gravels on the fabric, cover the perforated pipe with the fabric.

Step-6: Top up Your Drain or Channel with Gravels:

Fill up the Drain or channel with the gravels on the laid fabric. Use a knife to cut the excess fabric on both sides of the edges. After covering the pipe, label the pipe with soil lightly.

Maintenance of French Drain

It does not require to do more maintenance regularly. Once a year, it will be needed to clean, as the debris and leaves can form in the pipe hole.

The benefit of Using French Drain

Installing a French drain means you need to think about the best location and the depth of the channel you will dig. The purpose of installing it is to prevent water from entering your basement or setting pressure against your slab foundation. Installing a French drain will allow you to move away from moisture from the foundation. Your basement will not be wetly, or the French drain will help you dry up the water problem in your basement.

We use a French drain that can be used to keep water from getting together in your yard’s lower areas. It will help you if water flows towards the building or the other outdoor structure. A French drain can also help divert water, once you are constructing a maintenance wall on a steep slope.

4 Advantages of French Drain

A French Drain is a blessing for your land. It has many advantages. four main advantages are:

O1. Efficient drainage:

A French drain gives you significant benefits. It can transfer water away from your yard and home. You can install a French drain where you want with either interior or exterior French drain method. You can send water to the sump pump, or into a dry well, and to another place. It can help you keep your basement dry, which prevents your foundation damage.

O2. Affordable:

If you compare it with other waterproofing technics, a French drain is comparatively inexpensive.

O3. Transforms Your Lawn:

You can change your lawn into a garden or a children’s playground from the damp, wetly, and soggy lawn.

O4. Fast:

It is not complicated to install a French drain. The process of installing is quick comparatively.

How Long Should a French Drain Be

In this context, we will explain how long a French drain should be? To create a long French drain, it needs more pipes to add one part of the pipe with another depending on the areas’ distance.

How Long Should a French Drain Be?

There is no fixed size of a French drain. Depending on the required length of the area, a French drain is made by the users. It needs to add more pipes, one with another for the long-distance, and other materials like gravels, filter cloths, etc. will also be required accordingly. 

About French Drain Pipe

For creating a French drain, one of the standard material is plastic pipe. The plastic pipe is more durable than others. Generally, most people prefer two types of the tube while making French Drain in this aspect. They are corrugated pipe and PVC pipe.

The corrugated pipe is lightweight and flexible. At the same time, the PVC pipe is light, more robust, firm, and perforated. The PVC pipe is made of high-quality polyethylene, easily allows water inside it, and lets it give away through its process.

About Length and Width Of A French Drain

The French drainpipe has various sizes, such as each pipe 5-10 feet length, and different sizes of diameters. For the French drain system, people usually use the perforated pipe with a larger diameter at their home. Same is also applicable in agriculture uses.

A French Drain will be the most beneficial for you if you make and set up it rightly. Although every part of the project is essential, we have shown all the necessary information regarding “How Long Should a French Drain Be.” We hope it will help you apply this idea when you decide to go with a French drain at your home.

Final Thoughts

In conclusion, we hope you have learned more about a French drain, how it works, the installation process, maintenance technique, merits of a French drain, etc. You can apply for your purpose and benefit. Know the best electric hedge trimmers.