New Drain Installation: What to Expect

Whether you are building a new extension, constructing a new home, or completely replacing an outdated, collapsed system, a new drain installation is a significant project. It requires careful planning, adherence to building regulations, and expert execution.

At CleverWorks, we handle drain installations across London. To help you prepare, we have outlined the standard process of a new drain installation and explained why starting with a CCTV drainage survey is non-negotiable.

Step 1: The CCTV Drainage Survey & Mapping

Before a single shovel hits the dirt, we must understand what is already underground. A CCTV drainage survey is conducted to map the existing drainage network.

This survey identifies where the new pipes will connect to the existing system or the public sewer. It also ensures that the existing pipes are in good enough condition to handle the additional flow. Connecting a brand new extension to a crumbling, root-infested pipe is a recipe for disaster.

Step 2: Planning and Compliance

Drainage installations must comply with strict UK Building Regulations (specifically Part H). If you are connecting to a public sewer, you will also need permission from your local water authority (such as Thames Water).

Our team handles the technical planning, ensuring the correct pipe diameters are used, the gradients (fall) are calculated perfectly to ensure gravity flow, and adequate access points (manholes and inspection chambers) are included in the design.

Step 3: Excavation and Trenching

Once the plans are approved, the physical work begins. Trenches are excavated to the required depth and gradient. The bottom of the trench is lined with a bed of pea shingle or gravel to provide a stable, even base for the new pipes, preventing them from sagging or cracking under pressure.

Step 4: Laying the Pipes

The new pipes (typically durable PVC-U for modern domestic installations) are laid in the trench. Connections are made securely, and inspection chambers are installed at key junctions or changes in direction to allow for future maintenance and cleaning.

Step 5: Testing and Inspection

Before the trenches are filled in, the new system must be rigorously tested. This usually involves a water test or air pressure test to ensure there are absolutely no leaks in the new joints. Building Control officers may need to inspect the open trenches at this stage to sign off on the work.

Step 6: Backfilling and Reinstatement

Once the system passes inspection, the pipes are surrounded with more pea shingle to protect them, and the trench is backfilled with earth. Finally, the surface is reinstated, whether that means re-laying turf, paving stones, or tarmac, leaving your property neat and tidy.

Planning a drainage project? Start it right. Book a CCTV drainage survey today or call CleverWorks on 01932 544 095 for expert installation services.