Land Drain (9)

Land Drain: Your Essential Guide to Surface Water Drainage

A land drain, also known as a perforated drain pipe or French drain, is a vital tool that is used to prevent waterlogging in domestic, commercial, agricultural, and industrial areas.

Excessive rainfall and impermeable soils, such as clay, can lead to waterlogged ground, causing standing water, flooding, and poor soil irrigation. A properly installed land drain system redirects water effectively, protecting your property and improving the health of land.

The following guide helps to provide further information relating to land drains, including their types, functionality, installation recommendations, and tips for optimal performance.

Table of Contents

1. What is a Land Drain?
2. Types of Land Drains
3. How Does a Land Drain Work?
4. Where Should You Install a Land Drain?
5. Installation Tips for Land Drains

1. What is a Land Drain?

A land drain is a perforated pipe surrounded by aggregate that allows water to flow from waterlogged soil into the pipe. By redirecting this water to a designated location, land drains help manage excess surface water, reduce flooding risks, and improve soil drainage.

Land drains are widely used in gardens, fields, agricultural land, and construction projects to keep the ground stable and dry.

2. Types of Land Drains

Land drains are available in two types, which are designed for different applications:

Perforated Pipe: Flexible and available in a range of diameters and lengths, land drain coils are ideal for general surface water drainage projects due to their perforation.

Twinwall Solid Pipe: Stronger and more rigid, twinwall pipes are designed to handle heavy loads, such as those found beneath driveways or roadways, but are solely used to direct water and not collect.

Both types are manufactured from durable high-density polyethylene (HDPE) from C&W Berry. It is worth noting that most land drains are black, which bares no significance to the type of water they carry. Unlike other pipes, land drains are not color-coded and are solely used for surface water.

3. How Does a Land Drain Work?

A land drain collects and redirects water from saturated soil. The system includes:

1. Perforated Pipe: Allows water to seep and collect into the drain
2. Twinwall Solid Pipe: Directs sub-surface water to a chamber or soakaway
3. Aggregate Layer: Surrounds the pipe to direct water into the perforations
4. Gradient: Ensures water flows naturally to an outlet

Water collected by the land drain is typically directed to:

• A watercourse, such as a stream or river (with permission from the Environment Agency)
• A storm drain (subject to local council guidelines)
• A soakaway, where soil permeability allows

4. Where Should You Install a Land Drain?

A land drain should be installed in areas prone to waterlogging or where soil fails a percolation test. Common locations include:

• Waterlogged gardens or lawns
• Agricultural fields with poor irrigation
• Areas with compacted clay soil

Please note, it is always advisable to check with your local council or authoriry prior to directing water to a storm drain or watercourse. Regulations may limit water flow rates or restrict access to protected watercourses.

5. Installation Tips for Land Drains

Follow these tips to ensure your land drain system is effective and durable upon installation:

Prevent Sediment Blockage - Use Either:

• Catch-pits: Collect sediment before it enters the pipe
• Geotextile Wrapping: Wrap the pipe with a non-woven geotextile to filter out soil particles. Pre-wrapped land drain coils are also an option but may limit size availability

Maintain Proper Gradient

Install the land drain with a gradient of 1 in 150. Avoid gradients steeper than 1 in 100, which can cause water to flow too quickly and damage the system.

Select the Right Soakaway Crate

Choose modern, plastic soakaway crates designed to handle consistent water flow. Traditional crates may fail under heavy or continuous drainage conditions.

Plan an Efficient Layout

For the best coverage, plan your land drain layout with the following in mind:

• Small areas: Keep the pipe within 2.5 metres of the surface
• Large areas: Use a herringbone pattern, ensuring a 10 metres radius for efficient water collection

It is also advisable to use a suitable aggregate such as pipe bedding to assist with drainage and support.

For further technical information relating to our range of land drain products and connectors, please telephone our main sales line on 01772 431 216 or email [email protected].