Underground Drainage Supplies

An underground drainage system carries foul water, rainwater or surface water below ground to an appropriate sewer, treatment system or approved discharge point. A typical system includes pipework and fittings alongside access points such as inspection chambers. The layout and destination of the pipework will depend on the drainage design and the type of water being carried.

Our underground drainage supplies and products are popular among those working in groundworks, construction and sewerage environments. Our understanding of these environments is from a unique standpoint; we’ve experienced them ourselves. Our range is suitable for building different drainage systems across groundworks and installations, perfect for plant hire and civils contractors. 

uPVC is one of the most common materials used for foul and surface water drainage below ground. It is lightweight, corrosion-resistant and easy to work with on site. Cast iron may be specified where its additional strength, fire performance or other material characteristics are required. Drainfast supplies both uPVC underground drainage and Halifax cast iron drainage systems.

uPVC pipe is light, easy to handle and resistant to corrosion, which makes it well suited to below-ground drainage work. It can be cut and connected relatively quickly on site, while the smooth internal bore helps maintain efficient flow. A wide range of compatible bends, junctions, couplers and chambers also makes it straightforward to build a complete system.

Drainfast’s main underground drainage range includes 110mm and 160mm pipework. Larger sewer systems are available in 200mm, 250mm and 315mm diameters. The correct size depends on the drainage design, expected flow and the role of the pipe within the system. A short branch serving one part of a development will not necessarily require the same diameter as a main sewer collecting flows from several runs.

That depends on the layout shown on the drawings. A typical installation may use bends for changes in direction, junctions where runs meet, couplers between pipe lengths and adaptors where different systems need to connect. Inspection chambers are also commonly installed to provide access for future cleaning and maintenance.

Check the pipe sizes, angles and connection points before ordering so the fittings match the planned layout.

The main difference is usually the scale of the system and the amount of water it needs to carry. Standard 110mm and 160mm underground drainage pipe is widely used around buildings and developments. Larger sewer pipe carries greater combined flows further through the drainage network.

Drainfast stocks sewer systems in 200mm, 250mm and 315mm diameters for projects where the design requires this additional capacity.

There is no single depth that applies to every underground drainage installation.

Depth is influenced by the required invert levels, pipe route, loading, ground conditions, connection point and the cover needed to protect the pipework. The drainage drawings and product installation guidance should therefore take priority over a generic depth measurement.

For more detail, read our guide to underground drainage installation.

Start with where the drainage needs to run and where it will eventually discharge.

Before excavation begins, check the pipe diameters, invert levels, gradients, junction positions and inspection chamber locations shown on the drawings. Existing services and drainage also need to be identified, particularly where new pipework is tying into an established system.

Access for future maintenance is worth considering at this stage too. Once the pipework is buried, correcting a poorly positioned chamber or inaccessible junction becomes much more difficult.

Different standards apply to different products, so there is no single British Standard that covers everything sold as underground drainage.

Drainfast product information for parts of the Vision range references BS EN 1401-1 and BS EN 13598-1. BS EN ISO 9001 is also referenced in relation to quality management during manufacture.

Always check the technical information for the particular product being specified rather than assuming the same standard applies across the entire system.

You can find more information in our guide to UK underground drainage regulations.

Yes, Drainfast offers both bulk pricing discounts and options for you to sign up for a trade account. Our bulk deals include discounts when you spend over a certain amount. By setting up a trade account with Drainfast, your business can benefit from preferential pricing and a dedicated account manager. Many of our repeat customers have a trade account with us.

Your UK location will depend on how fast we can deliver your underground drainage supplies. We always aim to get your supplies to you as soon as possible, and we have options for next-day delivery for some areas of the UK. See our delivery policy for more details.