Sustainable Drainage Systems (SuDS)

Sustainable Drainage Systems (SuDS) are becoming increasingly important in dealing with water falling on urban areas, given the demands of increasing urbanisation and climate change.

They are beginning to replace traditional methods which rely on underground piped systems to remove water from an urban area as quickly as possible.


SuDS, on the other hand, aim to mimic the natural drainage of the site before it was developed.

Rainfall and surface water is instead captured, allowing as much to be evaporated or soaked into the ground close to where it fell, much like a natural environment would.

This approach means that less of the water that falls on hard surfaces will directly travel to the watercourse, and that water which does is done so at a more natural rate.

SuDS features that are commonly used in urban developments include:

  • retention and Infiltration basins
  • swales and filter strips
  • filter drains
  • attenuation ponds and wetlands
  • permeable paving.

These methods sustainable drainage are often used in conjunction with one another, and rarely will any two sites share the same SuDS strategy.

Each site will have its own SuDS strategy designed specifically for that site which is based on its geographical characteristics (slope, geology, infiltration capacity).

A successful sustainable drainage system will therefore reduce the likelihood of flooding from watercourses due to runoff from towns and cities. They will also take the pressure off existing surface water and combined sewers, so urban surface water flooding will be less likely.

However from a more general viewpoint, SuDS have the potential to provide more pleasant and amenable open spaces in new urban developments and spaces for biodiversity to flourish. They may also serve as pollution filters, meaning that fewer pollutants washed off roads will reach and contaminate watercourses.

Our role in SuDS development

Our role as the SuDS Approval Body is to approve, adopt and maintain all new SuDS serving more than one property within the county.

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