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Sustainable Drainage Systems (SuDS)

Sustainable drainage systems (SuDS) are ways of protecting against flooding in urbanised areas that are less able to deal with water.


SuDS are becoming more important in dealing with water falling on urban areas, given increasing urbanisation and climate change.

They are replacing traditional methods which rely on underground piped systems to remove water from an urban area.

SuDS aim to re-create the natural drainage of the site before it was developed. Trapping rainfall and surface water, this then evaporates or soaks into the ground close to where it fell.

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

SuDS features that are used in urban developments include:

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

These methods are often used together, and it is rare for any two sites have the same SuDS strategy.

Each site will have its own SuDS strategy designed based on its geography (slope, geology, infiltration capacity).

A good sustainable drainage system will make flooding from watercourses due to runoff from towns and cities less likely. It will also take the pressure off of existing surface water and combined sewers.

SuDS can provide better open spaces in new urban developments, allowing for better biodiversity. They are also pollution filters, meaning that fewer pollutants washed off roads will reach watercourses.

Our role in SuDS development

As the SuDS Approval Body, we approve, adopt and maintain all new SuDS serving more than one property within the county.