Installing an underground drainage system for a new build requires careful planning from the start. The system must be fully compliant with Building Regulations, with trenches excavated to the correct depth to protect existing pipework and nearby structures. Underground drainage supplies must be durable enough to handle the expected flow capacity to keep surface water, debris and solids moving and prevent blockages. Long-term maintenance also needs to be supported through well-positioned inspection chambers and accessible drainage runs.
Underground Drainage Explained
Underground drainage is a system that manages the flow of surface water, foul water and wastewater. It consists of robust pipework and fittings designed to transfer water away from a property safely. In domestic new builds, underground drainage protects the structure of a property by preventing flooding and ensuring waste is carried off to its appropriate destination.
For new builds, underground drainage is designed and installed from the ground up, allowing pipe routes, gradients and access points to be planned before foundations and external surfaces are completed. This makes it easier to achieve compliance and ensures the drainage system is correctly sized for the property’s expected usage.
The Importance of Underground Drainage
Underground drainage plays a vital role in keeping wastewater and surface water flowing safely away from a property. Without a well-designed underground drainage system, water can build up around foundations, increasing the risk of flooding and structural damage.
In new build properties, effective underground drainage helps ensure foul water and rainwater are directed to the correct discharge points, such as public sewers or private treatment facilities. A properly installed drainage system is also important to ensure a hygienic environment by preventing wastewater from leaking into the surrounding ground. It consists of durable pipes, fittings, chamber bases and risers that help ensure reliable long-term performance.
Key Considerations for Choosing Underground Drainage
Selecting the right underground drainage system for a new build project depends on several key factors, including the type of development, suitable materials, load ratings, system compatibility, regulatory compliance and overall site capacity.
Project Type
The project type will dictate the type of underground drainage system that will be required. Domestic new builds require drainage solutions designed to handle lower flow volumes and lighter load ratings than commercial projects. Residential drainage focuses on managing foul water and preventing it from accumulating. Commercial projects often require higher capacity pipework, stronger materials and more complex layouts to support the increased usage and demand.
Materials
When selecting materials for underground drainage, durability and resistance to harsh conditions are key considerations. uPVC and PVC are commonly used for drainage pipes and fittings due to their strength and long-term resistance to chemicals, abrasion and impact. Aluminium is often used for components such as grates and sealing plates where corrosion resistance is required. Polyethylene is typically used for base shafts, while polypropylene is commonly specified for inspection chamber bases with straight channels, offering excellent structural performance in underground environments.
Load Ratings
Load ratings are an important factor when choosing underground drainage products, as different components are designed to withstand varying levels of weight and traffic. Manhole covers and access covers are classified in accordance with BS EN 124, which sets out load classes for pedestrian areas, driveways and locations subject to vehicle traffic. Understanding load ratings is essential, as the required rating varies depending on the application. The correct load rating can help ensure safety, prevent structural failure and support long-term system performance.
System Compatibility
When selecting an underground drainage system, it is important to ensure all components are fully compatible. Pipes, fittings, inspection chambers and access covers should be designed to work cohesively. A complete and compatible system can help make installation straightforward, as well as simplify any future maintenance and testing.
Regulations and Compliance
As with any large-scale installation on a new build, compliance with industry regulations and standards is essential. Underground drainage systems must be designed and installed in line with Building Regulations and relevant British Standards to ensure safety. Ongoing compliance also depends on providing suitable access for inspection and maintenance over time. Inspection chambers and access points must be positioned to allow the system to be maintained efficiently throughout its lifespan.
Site Capacity and Conditions
Site capacity and conditions also play a key role in underground drainage design for new builds. It is important to consider factors such as expected rainfall levels, roof area and paved surfaces, as these all influence the volume of water the system must manage. Pipe sizes and gradients should be carefully selected to support efficient flow and reduce the risk of blockages. Assessing site conditions early provides a clearer picture and helps ensure the drainage system can cope with peak demand and long-term use.
Tips for Choosing Underground Drainage
Choosing the right underground drainage products can make a significant difference to the success of a new build project. Working with experienced, reliable suppliers helps ensure product quality, system compatibility and smoother project planning from start to finish.
- Choose a reliable supplier with positive reviews
- A supplier that uses a material take off service can help you with project planning
- Check product compliance to ensure they meet load ratings and British Standards
- Consider system compatibility to ensure all components work together seamlessly
