Guidance for developers
Surface water flooding occurs when rainfall falls onto low or non-permeable surfaces and does not infiltrate or is not suitably collected and conveyed by a drainage system. Flooding due to surface water is predicted to increase due to the effects of climate change. Therefore, it is important that surface water and associated drainage systems (both existing and proposed) are considered early on in the planning phase for all developments.
As a Lead Local Flood Authority (LLFA), we are responsible for managing flood risk from surface water, groundwater and ordinary watercourses throughout the borough.
We are committed to reducing surface water runoff flowing into sewers by requiring the use of Sustainable Drainage Systems (SuDS) in all developments. This is in line with the London Plan and will help to reduce the risk of surface water flooding throughout Southwark.
In our role as the LLFA, we will review planning applications from a flood and drainage perspective. In order to ensure that suitably detailed information is provided within each planning application, we have created the developers' guide for surface water management to inform all developers of the minimum requirements for planning submissions. This information includes:
- Requirements for Flood Risk Assessments and Drainage Strategies
- Guidelines for hydraulic calculations
- Guidelines for SuDS assessments and selection
- Details of common issues encountered with planning submissions
This document has been created to provide suitable advice to developers to ensure that planning applications are submitted correctly (from a flood and drainage perspective) and are reviewed and approved as quickly as possible.
However, we recommend that pre-application discussions take place. The more issues that can be resolved at pre-application stage, the greater the benefits to both Southwark council and the applicant.
Page last updated: 14 June 2023
