Underground service pipe colours and depth requirements

Underground service pipes are an imperative feature to every commercial or domestic build, as the underground pipe system is what provides utilities to any given building. Plus, it's not just household utilities that require a structure of cables and pipes to carry them towards, in, and around the building. Communications such as motorway information signs, traffic cameras and street lighting all need to be connected through underground service pipes to allow successful functionality. Through working with specific ducting colours for different utilities, it helps to protect pipework during excavation and avoids damage, as each service is easily identifiable.

Legally, underground service pipes must be encased in coloured ducting. This is to protect the pipes and cables from damage, alongside preventing minor and serious injuries to the on-site workers. In addition to colour coding, underground service pipes have to adhere to specific minimum depth regulations to again reduce risk of damage, and harm to humans and wildlife. There are different depth minimums for underground ducting depending on where the pipework is being installed – for example under public footpaths, private land, or public carriageways. We provide more details on this later in the post.

Service pipe colours

The below list provides information on all the underground utility colour codes:

Black or red service pipes

Black (and sometimes red) pipes are used for transporting power supplies and electricity cables. Red is most likely to be used for high voltage cables, although this does vary by area. They are available in a range of sizes to suit a variety of building projects and can be purchased in straight lengths, flexible, split and non-split for ease of use.  

Green service pipes

Green ducting indicates utilities such as CCTV, broadband and cable TV. Please note, this is true of domestic and commercial buildings projects, but not on motorways.

Yellow service pipes

Yellow service pipes carry natural gases. There are two separate yellow pipes, the duct and the gas service pipe. The service pipe goes inside the duct and the duct is perforated to allow gas to vent safely in the event of a leak.

Orange service pipes

Streetlights, traffic lights, traffic signalling and alarms are indicated using orange service pipes.

Blue service pipes

Blue ducting houses underground water pipes. They connect drinking water to a building and are also sometimes referred to as alkathene pipes. Water pipes come in a variety of sizes, and it’s important to note their depth regulations due to their risk of freezing in cold weather.

Purple service pipes

Purple service pipes are used specifically for motorway communications. This includes things like SOS telephones, traffic cameras and speed cameras.

Grey service pipes

You may also come across grey PVC ducting. This is used for general purpose cables and pipes, but usually encompasses things like telephone cables.

Service pipes depth regulations

The minimum depth of service pipes generally depends on what pipes are being laid. You should always refer to the guidelines from the local utilities companies when working on a project, but as a general guide, you can refer to the following:

• Black: 450mm for public footpaths, 600mm for carriageways.
• Red: 450-1200mm for public footway and 750-1200mm for carriageways.
• Green: 250-350mm.
• Yellow: 600mm for a public footpath, and 750mm for a carriageway.
• Orange: 300mm for public footpaths and 450-600mm for carriageways.
• Blue: 750mm for both footpaths and carriageways to avoid frost damage.
• Purple: 450-600mm underneath carriageways 

We hope this blog post acts as a useful guide for underground ducting colours and their minimum depth requirements. If you're looking to purchase ducting for underground service pipes and have any questions, please feel free to contact us and speak to our drainage experts.