What are Sustainable Urban Drainage Systems (SUDS)

SUDS, or Sustainable Urban Drainage Systems are a sequence of water management practices and facilities designed to drain surface water in a manner that will provide a more sustainable approach than what has been the conventional practice of routing run-off through a pipe to a watercourse or sewer.

SUDS work by using and combining the following techniques:

  • Surface water attenuation (storage).
  • Reducing the rate of surface water runoff.
  • Controlling surface water at source.
  • Infiltrating surface water to the ground.
  • Treating urban surface water from roads, driveways and roofs.
  • Evapo-Transpiration of surface water (green roofs etc).
  • Recycling surface water for use around the property.

Examples of SUDS:

  • Balancing Ponds/Detention Basins
  • Swales
  • Wetlands and Reed Beds
  • Engineered Soakaways
  • Permeable Paving
  • Permeable Tarmac
  • Rainwater Harvesting
  • Flow Control Devices
  • Oil Bypass Separators
  • Silt traps
  • Water Butts
  • Green Roofs
  • Oversized Pipes and Box Culverts
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Hierarchy of SUDS:

All sites are different when it comes to sustainable drainage so knowing what products to choose can be very difficult. The SUSTAINABLE DRAINAGE CENTRE will help you select the right product for the right scenario. We don't supply one particular range of products so we can offer you an excellent range of choice. Our consultancy services will provide you with the right advice and the right products. We are engineers, not sales people so will not try and force a product on you which is not suitable for your project.

Generally speaking 'soft SUDS' are preferred to man made products. The reason for this is soft SUDS such as swales and ponds mimic natural drainage systems. Soft SUDS on the whole tick the boxes of all three key factors to consider when designing SUDS. These are improving water quality, reducing rate and volume of flow and providing multi-functional amenity space. The main issue developers face when installing soft SUDS is they can take up lots of developable land. It is essential in the future that consideration is given to incorporate land allocated for public open space with land to be allocated for sustainable drainage.

Man made or engineered SUDS also have their advantages. A soakaway crate for example, can offer a void ratio of up to 95%. Gravel only offers around a 30% void ratio therefore crates are much more efficient. Soakaways are some of the best sustainable drainage systems as they promote surface water infiltration to the ground and encourage ground water re-charge. Flow control devices enable efficient use of storage and reduce flows with no moving parts, permeable paving is used to treat surface water and even the humble waterbutt can store on average 200 litres of stor m water.

The SUDS approval body will be looking for developers to submit sustainable drainage schemes which equally address the three main areas of 'the SUDS triangle'. This means quality of runoff, quantity of runoff and biodiversity of the system must be considered to carry equal weight when designing sustainable drainage.

We recommend you provide us with details of your project at the earliest stage possible. This way we can provide you with a design that is most suited to your development and budget, but will also meet your requirements in providing suitable sustainable drainage.

We are unique in our approach to SUDS design and will assist you from concept design to adoption. Please Contact Us for further information.