Northern Ireland Planning Service

PPS 15: Planning and Flood Risk
Annex C: What are Sustainable Drainage Systems?

C3 Also known as Sustainable Urban Drainage systems,16 sustainable drainage systems is the generic name for a range of techniques which seek to deal in an integrated way with the issues of water quantity, water quality and amenity. They seek to manage surface water run off as near to source as possible, slowing down run-off, treating it naturally and releasing good quality surface water to watercourses or groundwater. Their use involves moving away from a reliance on traditional underground pipe drainage systems to engineering solutions that replicate natural drainage processes.
C4 There is a wide range of sustainable drainage techniques17 available which can be applied, individually or in combination, to meet the particular drainage needs of a scheme. These include:
  • source control techniques that seek to counter increased discharge from development sites by dealing with run-off as close to source as possible and minimising the quantity discharged to watercourses; and
  • permeable conveyance techniques that slow the velocity of runoff to the receiving watercourse, allowing storage, filtering and some loss of water through evaporation and infiltration before the discharge point.
16 The word urban is intended only to convey a concern with surface run-off from the built environment, thus it is as applicable in rural, as in urban situations.
17See for further information, Sustainable Urban Drainage Systems, an introduction (Scottish Environmental Protection Agency Opens link in a new browser window, the Environment Agency Opens link in a new browser window and Environment and Heritage Service Opens link in a new browser window) and Sustainable Urban Drainage Systems, Design Manual for Scotland & Northern Ireland Opens link in a new browser window (Construction Industry Research and Information Association, 2000)
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