Drainage

What Is Drainage? 

Drainage is the process of removing excess water, typically rainwater or wastewater, from an area to prevent flooding, erosion, or structural damage. It involves systems that collect, channel, and direct water away from buildings, roads, and land.

There are two main types of drainage:

• Surface Drainage: Removes water from the ground’s surface using slopes, gutters, and channels.
• Subsurface (Underground) Drainage: Uses buried pipes or systems to collect and move water below ground level, often from foundations, basements, or saturated soil.

The Importance of Drainage

Drainage that isn't managed effectively will inevitably lead to a cascade of serious and costly problems for a property. What may appear as a harmless puddle is often the first sign of unmanaged water, which is the root cause of many severe and expensive-to-fix problems.

Key signs of poor drainage include:

• Structural Damage: This is the most serious outcome. You can spot it by looking for cracks forming in foundations and interior walls, noticing that doors or windows suddenly begin to stick shut, or feeling that floors have become sloped. These are all indicators that trapped water is pushing against your foundation, causing the house to slowly shift or settle.
• Damp, Mould & Rot: Water ingress through walls and floors creates damp patches, promotes toxic mould growth, and can rot structural timber.
• Waterlogged Gardens: Soggy lawns, flooded patios, and dying plants are classic signs that surface water has nowhere to go.
• Leaking Basements & Cellars: A common and destructive issue caused directly by inadequate foundation drainage.

A well-installed drainage system stops these problems before they start. 

Key Components of an Underground Drainage System

An effective drainage network is made up of several vital components working together. Understanding the role of each part is key to designing and installing a system that works.

Primary Channel: Underground Drainage Pipe

The underground pipe is the primary channel of any drainage system, acting as the main highway for transporting water safely away from your property. 

Modern pipes are typically made from durable, corrosion-resistant PVC and come in standard sizes, with 110mm being the most common for residential applications. 

Pipes can be solid for transporting water directly, or perforated for systems like French drains and soakaways where the goal is to disperse water back into the ground along a trench.

Changing Direction: Bends and Junctions

A drainage system rarely runs in a straight line. Degree Bend Double Sockets and junctions are essential fittings used to navigate corners, join pipe runs together, and bypass obstacles. 

Using smooth, sweeping bends rather than sharp angles is crucial for ensuring an efficient, non-blocking flow of water. These fittings are available in various angles to provide the flexibility needed for a professional installation.

Collecting Surface Water: Bottle Gullies & Catch Basins

Areas like driveways, patios, and paved walkways are prone to surface water accumulation. Bottle Gullies and Catch Basins are installed at ground level to collect this runoff and feed it into the main underground system.

• A Bottle Gully features a water trap within its chamber that cleverly prevents odours and gases from the underground pipes from escaping. Its top grid filters out leaves, stones, and other debris.
• A Catch Basin (or sump basin) acts as a collection point for both water and silt, helping to prevent the main pipework from clogging during heavy rainfall.
  
  

Channel Drainage

Channel Drainage, also known as linear or trench drainage, is a surface water management system designed to effectively clear water from large, flat areas. You will typically see it installed across driveways, patios, pedestrianised areas, and in front of garage thresholds. 

The system consists of a long, linear channel set into the ground, covered by a grate. This design allows it to intercept and collect rainwater along its entire length, directing it into the main underground drainage network. 

Inspection Chambers

An Inspection Chamber is an essential access point within an underground drainage system. It serves as a sealed, subsurface junction box that allows for the maintenance, testing, and clearing of pipework without the need for extensive excavation. 

Typically installed where branch pipes connect, at a significant change in direction, or along long straight runs, these chambers are vital for the long-term health of any drainage network. Their modular design allows them to be built up to the required depth, and they are capped with a manhole cover that provides secure access from the surface.