How to Design A French Drain System

By Danika | July 7, 2022

How to Design A French Drain System

french drain system diagram

French drains or perforated pipe drain systems are designed to remove water from low areas in a yard. A French drain is easily installed by digging a trench and placing pipes in the trench. They are good for removing surface water and preventing groundwater from traveling by gravity closer to homes. Many people make mistakes that may end up costing them a lot. It is therefore very important for people to identify the mistakes they make in the process of installing a French drain and follow the proper steps by which they can successfully complete the same. Here is an ultimate guide on how to design a French drain system.

Know Your Soil Type

Before you install a French drain, you should know your soil type. The type of soil will determine the type of pipe that you need and the length of pipe you need to dig. Know your soil type so that you can check for water traps, which are places where groundwater enters your French drain pipes through potholes or other gaps. For clay soils, it will be hard for French drains to work well. The texture of clay soil is such that it is hard to dig and it tends to stick to whatever you dig in.

But for sandy loam soils and sandy soils, a French drain is easy to install and can work very well. Sandy soils have air spaces that allow rainfall water to drain into the pipe easily.

knowing your soil types (these 6 types) is part of how to design a French drain system
Image source: Mother Earth News

Choose the Right Drain Pipe

Before you begin, you need to consider the length of the drain pipe that you will be using and the number of pipes that needs to be cut, and how wide they should be. The pipe should work well in your soil. It should drain the water from all directions. It is important that you use a long-lasting pipe that is not affected by tree roots. You should use a drain pipe that is 2 times bigger than the expected flow rate. For example, if your soil will drain at 3 inches per hour, you should use 6-inch pipes.

drain pipes to use for a French drain

Use the Right Gravel

It is very important to use the right gravel when sloping your drain. Gravel will help you achieve maximum slope. You must not use larger materials such as rocks or stones to achieve the slope because they will only slow you down in achieving the right slope. Using too small gravel will also slow you down. It’s advisable that you use the right size of gravel to help filter out debris so as not to clog the pipes.

gravel allows you to control the slope of the drain pipes

Slope the Drain Properly

In sloping the drain, you need to make sure that the water will drain away from your house. It should not flow towards your house but away from it.

In most cases, people mistake the direction in which we should slope the pipe. As mentioned earlier, the water should move away from your house.

The standard slope is 1/4 inches per foot. This way you will achieve effective drainage.

French drain collecting water and sloping down to carry water away from home
Image Source: Masseo Landscape

Install a Catch Basin at the Low Point

You need to install a place where water will gather before going into the drain. This place is known as a catch basin. In other words, this is where all the extra drainage water goes. It is a place where water accumulates so that it does not go into your house.

If you install a catch basin at a place where the water accumulates, you will not have to worry about your pipe overflowing when you are in a rainy season.

A Catch basin is how to collect the water in a french drain
Image source: NC Drainage

Hire a Professional

If you are not aware of how to install a French drain, you should hire a professional to help you. You should never try installing a French drain on your own because this may cause you a big loss. Our professional drain installation team will be able to give you expert advice, help you with all the procedures that need to be followed, and are always available when you need them. They will also never leave you in the lurch, so you can be sure that your problem will be resolved within a short span of time.

The main thing to remember when you are planning to install a French drain is that the water should move away from your house and not towards it. You should also use the right size of gravel when you slope your drain. It is also very important to know what you are doing. Know the mistakes that are commonly made and follow the right procedures in tackling such mistakes. Remember to hire our professional plumbing company to help you out when you are not sure of what you are doing.

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