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Sustainable Urban Drainage


Sustainable Drainage Systems (SUDS) provide a more sustainable approach to managing water. They aim to mimic the way water moves naturally in and around a green field site. This differs from conventional drainage systems where rainwater runs quickly off hard surfaces, straight into drains and then into rivers, often carrying pollution with it. SUDS involve a range of techniques such as green roofs, rainwater harvesting, permeable paving and landscape features such as ponds and wetlands.

Benefits of SUDS

SUDS provide a range of benefits over conventional drainage systems:

  • Reduced flood risk – SUDS slow down the flow of rainwater from a site by filtering and storing it. This reduces pressure on our overstretched drainage system and therefore reduces the risk of flooding, especially after heavy rainfall. This is particularly important as our drainage system is under increasing pressure due to development and the increased risk of heavy rainfall due to climate change.
  • Improved water quality – SUDS features such as green roofs and permeable paving filter and clean rainwater on site. This ensures water entering drains and then London’s rivers is free of oil and pollutants which can harm wildlife.
  • Benefits for people and wildlife – SUDS creates opportunities for rainwater recycling and for creating attractive water features which support wildlife. SUDS also reduce the need for expensive conventional drainage systems, and thus can provide cost savings.

SUDS techniques

SUDS techniques most likely to be used in Islington include:

  • Rainwater harvesting - rainwater can be collected from roofs for reuse in flushing toilets or, most simply, can be collected in a water butt for use in watering plants and landscaped areas.
  • Green roofs – planted ‘green’ roofs store and clean water as well as providing habitats for wildlife - see 'Green roofs, walls and biodiversity' page
  • Soft landscaping – landscape features, such as rain gardens, ponds and wetlands, can be designed to collect and store runoff
  • Permeable paving - rainwater filters through permeable paving where it is stored before soaking into the ground or entering drains.

The council requires SUDS on all new major developments. SUDS techniques can also be incorporated into existing buildings.

Further information

  • For an overview of SUDS techniques relevant for Islington see the SUDS Good Practice Guide (see pdf at bottom of page)
  • For SUDS case studies in Islington see the link to the SUDS Case Studies page below
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