What Is a Sustainable Drainage System (SuDS)?
A technical overview of Sustainable Drainage Systems: what they are, why they matter for planning, and how they mimic natural catchment responses to rainfall.
What Is a Sustainable Drainage System?
SuDS stands for Sustainable Drainage Systems. According to Schedule 3 of the Flood and Water Management Act 2010, a drainage system is defined as “a structure designed to receive rainwater, except a public sewer or a natural watercourse.”
Since April 2015, SuDS implementation has been mandatory for major development applications. The systems may also be required for minor developments, permitted development, or conversions within Greater London under the London Plan.
The Philosophy Behind SuDS
The approach emphasises slowing and reducing surface water runoff from developed areas. The strategy involves “harvesting, infiltrating, slowing, storing, conveying and treating runoff on site” with visible water features integrated into the built environment.
SuDS design pursues four key objectives: water quantity management, water quality protection, biodiversity enhancement, and amenity value creation.
What Does SuDS Do?
The system mimics natural catchment responses to rainfall. Core principles include:
- Managing water near its source
- Reducing water exit velocity from sites
- Promoting infiltration and evaporation
- Designing systems resilient to intense future rainfall
Implementation Guidance
Successful SuDS integration requires early planning engagement, adequate physical space allocation, and expert consultation to identify appropriate site-specific measures before finalising drainage strategies.