Choosing the right underground drainpipes may seem like a minor detail, but these pipes are crucial to the overall performance of your drainage system. Whether you are installing a new driveway, landscaping your garden, or addressing water flow issues, selecting the correct pipes ensures a drainage system that functions efficiently for decades, protecting your property from persistent flooding and costly excavation work.

With years of experience manufacturing high-quality, reliable underground drainpipes, we understand the significant impact the right pipe can have on water management throughout your property. To assist you in making an informed choice, we’ve created this guide to explain the different types of pipes and the role each plays in building a dependable drainage system.

Why Underground Drainage Matters

Underground drainpipes work quietly beneath the surface to manage water effectively around your property. While your gutters and downpipes channel water away from your roofline, this water still needs a safe path to drain. A well-designed underground drainage system ensures that rainwater and runoff are efficiently directed away from your property. Without it, water can pool on the surface, leading to flooding, soil erosion, and potential structural damage. These drains quickly and efficiently carry water into the main sewer network, protecting your property from long-term damage.

Whether you are building a new extension, laying a patio, installing a driveway, or simply resolving a drainage issue, understanding your underground drainpipes can save you significant time, money, and hassle.

The Main Types of Underground Drainage Pipe

Today, most drainpipes are made from uPVC (unplasticized polyvinyl chloride), a material that offers numerous advantages. uPVC is lightweight, durable, and resistant to corrosion, and it is readily available in the most common domestic and commercial sizes. Underground uPVC drainpipes are typically orange terracotta in colour, which is standard for both surface and foul water drainage.

There are various types of underground pipes to suit different applications, and it’s important to choose the right size and type for your needs. General waste pipes, suitable for most residential properties, are commonly available in 110mm and 160mm diameters, with a range of fittings to create an efficient drainage system. For heavier-duty applications, such as under roads or in commercial car parks, specialist pipes are designed to withstand larger loads without risk of crushing.

Sizing Your Underground Drainage System

For most properties, 110mm underground pipes are sufficient, while 160mm underground pipes provide a better solution for larger properties that require greater water drainage capacity. Both sizes are considered industry standard and are designed to connect seamlessly with downpipes, gullies, and basic surface water systems.

As a general guideline, underground pipes should be installed with a fall of at least 1:40, meaning the pipe drops 1 unit for every 40 units of horizontal run. This gradient ensures water flows freely and prevents solids from settling in the pipe, which can lead to blockages over time. Achieving the correct gradient during installation is critical, so it is recommended to engage a specialist plumber for the task.

Inspection Chambers and Rodding Points

Underground drainage systems should incorporate inspection chambers at any change of direction as well as at any pipe junctions and at regular intervals along straight runs. These chambers allow for easy access to the underground system which is crucial for inspection and maintenance and will ensure that excavating isn’t always needed.

Getting the Installation Right

The installation of your underground drainage system plays a critical role in its performance and longevity, making it essential to get it right. Pipes should ideally be laid on a bed of gravel or another type of granular material, as larger stones or heavily compacted soil can crush or deform pipes over time.

While straightforward drainage projects may not require planning permission, more complex underground installations must comply with building regulations and obtain the necessary approvals. This is why professional installation is strongly recommended.

Quality matters, not only in selecting your drainpipes but also in choosing who installs them. Pipes and fittings must meet industry standards, and the installation itself must be done correctly to ensure long-term reliability. Selecting high-quality materials and an experienced installer is key to preventing problems in the future.

By planning your drainage system carefully from the outset, using the right materials, ensuring correct installation, and adhering to all relevant standards, you can create a drainage system that remains reliable for years to come.