French Drain: How to Install and How It Works

You might have seen french drain around homes and landscapes, but do you know how vital they are? 

A French drain pipe isn’t just another pipe in your plumbing system—it plays a significant role in protecting your property from water damage.

Mastering how it works is not a duty, but it helps in some ways. You get to give your plumbing system proper maintenance services so you can prolong their lifespan. 

Ready to learn more about French drain installation? Let’s get started!

What is a French Drain and How Does It Work?

A French drainage system is there to keep water away from areas where it can cause problems. Basically, it’s a plumbing fixture that redirects water to prevent flooding or pooling. 

It consists of a trench filled with gravel or rock, with a perforated pipe at the bottom. The design allows water to flow through the gravel and into the pipe, which then directs it safely away from your property.

It works like this: when it rains or when water accumulates for any reason, it seeps through the gravel or rocks in the trench. 

The perforated pipe at the bottom collects the water and carries it away to a safe drainage point, such as a storm sewer, a dry well, or another designated area. 

These are where you can usually found the french drain system:

• Around the foundation of homes to prevent basement flooding.
• In gardens and lawns to stop water from pooling after heavy rain.
• Along driveways or walkways to redirect runoff.
• Near retaining walls to reduce water pressure buildup.

How to Install a French Drain System

Follow these steps and you’ll be done in no time:

1. Plan the Location

Start by identifying the area where water tends to collect. Mark the route for the drain, ensuring it slopes downward so water can flow naturally to a safe drainage point. This could be a storm drain, a dry well, or another low-lying area.

2. Dig the Trench

Use a shovel or a trenching tool to dig a trench along the planned path. Make sure it’s about 12 to 18 inches deep and 9 to 12 inches wide. The slope should drop about 1 inch for every 8 to 10 feet of length to ensure proper water flow.

3. Line the Trench with Landscaping Fabric

Lay landscaping fabric along the trench. This prevents soil and debris from clogging the system while allowing water to flow freely. Leave extra fabric on the sides to wrap over the top later.

4. Pour Gravel Bedding

Add a few inches of gravel to the bottom of the trench. This creates a stable base for the drain pipe and helps with water filtration. Make sure the gravels are compact down there.

5. Install the Inlet Grates

Position inlet grates along the trench, especially in areas where water collects the most. These grates let surface water enter the drain easily. 

6. Connect the Pipes

Attach perforated pipes securely to ensure water flows into them. Make sure the holes in the pipes face downward to collect water from the gravel layer effectively.

7. Set the Drain Pipe and Cover with Gravel and Fabric

Place the perforated pipe in the trench over the gravel. Add more gravel on top until it’s just below the surface. Then, fold the landscaping fabric over the gravel to prevent debris from entering the system.

8. Put the Topsoil

Finish by adding a layer of topsoil over the trench to restore the area. You can also plant grass or other landscaping features to blend the drain into your yard seamlessly. Ensure everything is neat.

Benefits of Installing a French Drain System

As you’ve read above, installing a French drain system effectively prevents water from pooling in unwanted areas. 

It protects your foundation and basement from potential flooding and water damage. This system also reduces soil erosion and maintains the integrity of your landscaping. 

Additionally, it  minimises the risk of mould and mildew caused by damp conditions, creating a healthier environment in and around your home. 

FAQ about French Drain System

What is the average cost to have a French drain installed?

In Australia, the cost of installing a French drain typically ranges from $1,500 to $5,000, depending on the project’s size and complexity. Factors like trench length, materials, and whether you hire professionals will impact the price.

What are the disadvantages of a French drain?

 They require regular maintenance to prevent blockages caused by debris and soil. The installation process can be disruptive to your garden or landscaping, and improper installation can lead to inefficient drainage.

How deep should a French drain be in the ground?

A French drain in Australia is generally installed 30 to 45 cm (12 to 18 inches) deep, though this can vary depending on the property’s drainage needs. For areas with heavy rainfall or flooding, a deeper trench might be necessary.

Can I install a French drain myself?

Yes, you can install a French drain yourself if you’re confident in your DIY skills and have the right tools. However, for larger or more complex installations, it’s advisable to hire professional drainage experts to avoid costly mistakes.

Conclusion

Now that you know more about French drain installation, you might feel ready to give it a try yourself. But if you’d rather save time and ensure everything’s done perfectly, calling in the experts is always a smart move.