Drainage Design Services in London

• Review of existing drainage arrangements and available records
• Design of new foul and surface water drainage layouts
• Pipe sizing, gradients and invert levels
• Positions of manholes, inspection chambers and rodding access
• Connection points to existing drains or the public sewer

• House extensions that build over or near existing drains
• New bathrooms, kitchens or utility rooms in altered layouts
• Driveways and patios needing surface water management
• Landlord property upgrades where drainage is being renewed

1. 1

   Initial enquiry

   Tell us about your project through the contact form, including any drawings or photographs you already have.

2. 2

   Review of information

   We review the available information — existing drawings, architectural proposals, site measurements and photographs — and confirm what is needed.

3. 3

   Quotation

   We agree the scope and fee with you before any design work begins, so you know exactly what will be provided.

4. 4

   Design and checking

   We carry out the agreed calculations, drawings or specifications, checked against the relevant standards.

5. 5

   Issue of deliverables

   The agreed drawings, calculations or design notes are issued to you electronically, ready for your builder or building control.

• Architectural drawings or a sketch of the proposed work
• Any existing drainage plans, CCTV surveys or records
• Site address so public sewer records can be checked
• Photographs of existing manholes and inspection chambers

• Drainage layout drawings showing pipe runs, sizes and levels
• Design notes suitable for a building control submission
• Drainage calculations where required by the project

Some projects need a CCTV drainage survey or a build-over agreement with the water authority (in London, usually Thames Water) before work can proceed. Where these apply we will explain them, but third-party approvals and building regulations approval are not included in the design fee and cannot be guaranteed.

Do I need drainage design for a small extension?

Often, yes. If your extension builds over or near an existing drain, building control and possibly the water authority will want to see how the drainage is affected and protected.

Can you find out where my existing drains run?

We can review water authority records and any existing plans. Where the route is uncertain, a CCTV drainage survey by a specialist contractor is the reliable way to confirm it.

Does the design include building control approval?

No. We provide the drawings and calculations that support your application, but approval is granted by building control and is outside our control.

• Surface Water Drainage
• Foul Water Drainage
• Drainage Installation Repairs