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Diffuse pollution in the urban environment (SUDS)

Sustainable urban drainage systems

SUDS, or sustainable urban* drainage systems are a sequence of water management practices and facilities designed to drain surface water in a manner that will provide a more sustainable approach than what has been the conventional practice of routing run-off through a pipe to a watercourse.

*The use of the word 'urban' is frequently omitted, but the meaning is still the same.

1. Practices involved are what is termed 'good housekeeping' or 'best management practices'. Such practices include:

  • Mitigation of accidents that may result in pollution incidents;
  • Reduction of polluting activities;
  • Reduction of polluting materials;
  • Bunding of oil tanks;
  • Water harvesting.

2. Facilities are generally constructed arrangements. Such facilities include:

  • Permeable surfaces;
  • Filter strips;
  • Filter and infiltration trenches;
  • Swales;
  • Detention basins;
  • Bioretention systems / raingardens;
  • Wetlands and ponds.

Other facilities exist that often come as proprietary products offering hydraulic controls or silt trap arrangements. These may also incorporate materials with properties able to encourage adsorption of certain polluting substances such as oils and toxic metals.

We are the statutory agency responsible for protecting the water environment in Scotland, under the Water Environment Water Services (WEWS) Act. On that basis, we require the use of effective, appropriate sustainable urban drainage systems (SUDS) features in new developments.

Developers, SEPA and Scottish Water are encouraged to discuss proposed developments at an early stage, even before approaching the planning authority. Government planning advice is available in Planning Advice Notes (PANs) and Scottish Planning Policy (SPP) releases from the Scottish Government .

A national stakeholder group was established in 1997 - the Sustainable Urban Drainage Scottish Working Party (SUDSWP).

How are SUDS regulated?

Under the Water Environment (Controlled Activities) (Scotland) Regulations 2011 it is a general* requirement for new developments with surface water drainage systems discharging to the water environment that such discharges will pass through SUDS. All reasonable steps must be taken to ensure protection of the water environment.

* Two exceptions exist to this requirement:

  1. Where the development is only a single dwelling;
  2. Where the discharge is directly to coastal waters (this does not including transitional waters).

The Controlled Activities Regulations (CAR) provide regulation under general binding rules (GBRs) 10 and 11 for SUDS.

SUDS in Scotland - the Scottish SUDS database

The findings of a major survey into the use of sustainable urban drainage are summarised in the SNIFFER report  (SR (02) 09), 'SUDS in Scotland - the Scottish SUDS database'. The survey highlighted that the use of SUDS has become standard practice in Scotland, with over 700 sites being listed and nearly 4,000 systems having been implemented.

SUDS Working Party

The SUDS working party is a group of stakeholders who meet regularly to discuss key issues relating to sustainable urban drainage systems (SUDS). The group comprises representatives from:

  • Homes for Scotland
  • Landscape Institute Scotland
  • Royal Incorporation of Architects in Scotland (RIAS)
  • Scottish Enterprise
  • Scottish Government
  • Heads of Planning Scotland (HOPS)
  • Scottish Water
  • Society of Chief Officers for Transportation in Scotland (SCOTS)
  • SEPA

After the introduction of sustainable urban drainage systems (SUDS) to Scotland it became clear that national promotion of the concept was necessary to raise the profile of sustainable drainage. At this time SEPA was established and the formation of the SUDS working party was driven by SEPA to involve other key stakeholders.

The need for planners’ involvement, both at a national and local level was realised together with the obvious requirement of drainage authority (at the time of formation there were three in east, west and north of Scotland) involvement.

An obvious need was to establish recognised guidance for practitioners to use. Through collaboration with CIRIA  (Construction Industry Research & Information Association) the design guide 'Sustainable Urban Drainage Systems design manual for Scotland & Northern Ireland' was published in 2000. This document was replaced by the 'SUDS Manual (C697)' in 2007, which in November 2015 was superseded by The SUDS Manual (C753), available from CIRIA.

The Water Assessment and Drainage Assessment Guide (WADAG) was published by SUDSWP in January 2016.  This supersedes previous guidance ‘Drainage Assessment: A Guide for Scotland’. The WADAG is intended to help guide developers, planners and others involved in water and drainage infrastructure through the necessary stages to obtain relevant permissions and comply with standards and policies.

SUDS for Roads  , a national guidance manual, is a collaborative publication between SUDSWP and Society of Chief Officers of Transportation in Scotland (SCOTS) and was published in 2010.

Title/Organisation Name  Affiliation
Chair  Peter Pollard SEPA
Vice Chair Barbara Barbarito Scottish Water
Technical Secretary Andy Hemingway SEPA
Scottish Water Doug Buchan Scottish Water
Society of Chief Officers for Transportation in Scotland (SCOTS) Roads representative Emma Thomson Glasgow Council 
Society of Chief Officers for Transportation in Scotland (SCOTS) Flooding representative Ross Speirs Fife Council
Landscape Institute Scotland Julie Waldron Edinburgh City Council
Homes for Scotland Norman Kidd Walker Group
  Tom Mitchell Cala Homes
Scottish Government Bill Ellis Scottish Government (Planning)
  Antje Branding Scottish Government (Flooding)
  Clyde Ashby Scottish Government (Building Standards)
  Drew Hill Transport Scotland
SNH Swaantje Ridegh SNH, Perth
Scottish Enterprise Bill Gladstone Scottish Enterprise, Lanarkshire
Local Authority Building Standards Scotland (LABSS)

Steve Wilson

Perth and Kinross Council

Royal Incorporation of Architects in Scotland (RIAS) Alistair Hackland Hackland & Dore Architects
Heads of Planning Scotland (HOPS) Alastair Hamilton Fife Council

Wendy Campbell

SEPA Planning, Stirling Office

  Kirsten Thorburn SEPA Flooding, Edinburgh Office

Further information and links

There are a variety of publications and groups that can provide you with information on SUDS.


  • Susdrain   - A community that provides a range of resources for those involved in delivering sustainable drainage systems. Visit the website for case studies, resources and more.
  • SUDSNet - A Sustainable Urban Drainage Systems Network designed to promote and best practice within the field of SUDS. Visit their website for details of SUDS-related meetings, field sites, academic and industry links and more.