Sustainable drainage system

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Suds pond with reed-bed near housing, Dunfermline, Scotland.

A sustainable drainage system (also known as SuDS[1] or SUDS[2][3]) is designed to reduce the potential impact of new and existing developments with respect to surface water drainage discharges.[4] Sustainable drainage systems are often used in urban centers or other areas where rainfall is prevented from entering soil or water sources by impermeable surfaces such as pavement, concrete, asphalt, etc. SuDS have gained prominence as urban sprawl and population growth exacerbate strain on water management systems. The term sustainable urban drainage system[1][5] is not the accepted name,[by whom?] the 'Urban' reference having been removed so as to accommodate rural sustainable water management practices.[6][7]


Increasing urbanisation has caused problems with increased flash flooding after sudden rain. As areas of vegetation are replaced by concrete, asphalt, or roofed structures, leading to impervious surfaces, the area loses its ability to absorb rainwater. This rain is instead directed into surface water drainage systems, often overloading them and causing floods.

The goal of all sustainable drainage systems is to use naturally occurring rainfall to recharge the water sources of a given site. These water sources are often underlying the water table, nearby streams, lakes, or other similar freshwater sources. For example, if a site is above an unconsolidated aquifer, then SuDS will aim to direct all rain that falls on the surface layer into the underground aquifer as quickly as possible. To accomplish this, SuDS use various forms of permeable layers to ensure the water is not captured or redirected to another location. Often times, these layers include soil and vegetation though they can also be artificial materials.

The paradigm of SuDS solutions should be that of a system that is easy to manage, requiring little or no energy input (except from environmental sources such as sunlight, etc.), resilient to use, and being environmentally as well as aesthetically attractive. Examples of this type of system are basins (shallow landscape depressions that are dry most of the time when it's not raining), rain gardens (shallow landscape depressions with shrub or herbaceous planting), swales (shallow normally-dry, wide-based ditches), filter drains (gravel filled trench drain), bioretention basins (shallow depressions with gravel and/or sand filtration layers beneath the growing medium), reed beds and other wetland habitats that collect, store, and filter dirty water along with providing a habitat for wildlife.

Originally the term SUDS described the UK approach to sustainable urban drainage systems. These developments may not necessarily be in "urban" areas, and thus the "urban" part of SuDS is now usually dropped to reduce confusion. Other countries have similar approaches in place using a different terminology such as best management practice (BMP) and low-impact development in the United States,[8] and water-sensitive urban design in Australia .

SuDS use the following techniques:

A common misconception of SuDS is that they reduce flooding on the development site. In fact the SuDS is designed to reduce the impact that the surface water drainage system of one site has on other sites. For instance, sewer flooding is a problem in many places. Paving or building over land can result in flash flooding. This happens when flows entering a sewer exceed its capacity and it overflows. The SuDS system aims to minimise or eliminate discharges from the site, thus reducing the impact, the idea being that if all development sites incorporated SuDS then urban sewer flooding would be less of a problem. Unlike traditional urban stormwater drainage systems, SuDS can also help to protect and enhance ground water quality.


Drainage systems have been used in urban centers since antiquity, with early examples found in Bronze Age Minoan sites. Modern drainage systems did not appear until the 19th century, although most urban drainage systems at the time were built primarily for sewage purposes. Drainage systems for storm water surges were often combined with sewers, particularly in cities with older drainage systems. Within the past decades, as climate change and urban flooding have become increasingly urgent challenges, drainage systems designed specifically for environmental sustainability have become more popular in both academia and practice.

The first sustainable drainage system to utilize a full management train including source control in the UK was Oxford services designed by Robert Bray Associates, specialist SuDS consultants.[9]

See also[edit]


  1. ^ a b Sustainable Drainage System (SuDs) for Stormwater Management: A Technological and Policy Intervention to Combat Diffuse Pollution, Sharma, D., 2008
  2. ^ "CIRIA guide to SUDS". Retrieved 2014-01-21.
  3. ^ Scottish Government. Planning Services (2001). "Planning and Sustainable Urban Drainage Systems." Planning Advice Note 61. 2001-07-27.
  4. ^ CIRIA SuDS Manual (Document reference : CIRIA C753), 2015
  5. ^ Environmental investment may help local economy, 22 October 2002
  6. ^ CIRIA Publication, 'evolution' May 2010
  7. ^ Susdrain - CIRIA's Sustainable Drainage Website.
  8. ^ U.S. Environmental Protection Agency. Washington, DC (2006). "Fact Sheet: Low Impact Development and Other Green Design Strategies." 2006-06-01.
  9. ^ CIRIA Oxford Motorway Services Case Study

10. Variability of drainage and solute leaching in heterogeneous urban vegetation environs

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