Sustainable Drainage Systems (SuDS) Design in London

• Assessment of the site and its drainage constraints
• Selection of suitable SuDS measures for the property
• Design of permeable paving, rain gardens, swales or attenuation storage
• Sizing calculations based on rainfall and catchment area
• Maintenance guidance for the installed measures

• Extensions and new builds where the planning authority expects SuDS
• Driveways using permeable paving
• Gardens designed to absorb and slow rainwater
• Properties in areas prone to surface water flooding

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.

• Site plan showing existing and proposed areas
• Any planning conditions or requests from the local authority
• Ground conditions information where infiltration is proposed
• Details of the existing drainage arrangements

• SuDS layout and details drawings
• Sizing and storage calculations
• A drainage statement where one is needed for planning

Whether SuDS measures can soak into the ground depends on site-specific ground conditions, which may need investigation. Where infiltration is not possible, attenuation with a controlled discharge may be required, and discharge to a public sewer can need water authority approval. Planning requirements vary between London boroughs.

Will the council insist on SuDS for my extension?

It depends on the borough and the size of the project. Many London boroughs ask for a drainage statement showing how surface water is managed, particularly for larger extensions and new builds.

Is permeable paving as durable as normal paving?

Properly installed permeable paving performs well for driveways and patios, and it removes the need for separate drainage in many cases.

Do SuDS need maintenance?

Yes, but it is usually simple — keeping permeable surfaces clear of silt and occasionally clearing rain gardens. We include maintenance guidance with the design.

• Surface Water Drainage
• Drainage Design
• Driveways Hardstanding