Sustainable drainage systems (SUDS)

Surface water drainage systems which are established with overarching sustainable development objectives are referred to as Sustainable Drainage Systems (SUDS).

Sustainable urban drainage in Northampton. Photo by Stephen McLaren

Good surface water management will require increased use of such systems.

SUDS comprise a system of devices used for managing surface water run-off in a manner that aims to simulate the natural drainage systems. Rather than directing surface water into drains, SUDS devices encourage surface water to remain on site and infiltrate the ground. Well designed and maintained SUDS are more sustainable than conventional drainage methods because they mitigate the adverse effects of urban stormwater runoff on the environment.

This advantages are that that they:

• provide storm water attenuation that prevents flooding downstream
• protect and possibly enhance surface water quality
• improve ground water recharge
• provide habitats for wildlife
• are a landscape amenity for the community.

SUDS aim to reduce the amount and rate of water flow by a combination of:

• infiltration into the ground
• holding water in storage areas
• slowing down the movement of water.

A range of features provide for these roles.

Devices include:

• rain gardens and swales on kerbsides
• parks that become detention basins in heavy rain
• retention ponds
• constructed wetlands
• permeable paving
• green roofs
• rainwater harvesting - water that is harvested may be used for watering gardens or flushing toilets.

SUDS general principles and devices are also known in other parts of the world as water sensitive urban design (WSUD) or low impact urban design development (LIUDD).

The CIRIA SUDS Manual represents the central guidance on drainage systems. The Manual emphasises the importance of SUDS mimicking natural catchment processes through the establishment of a “management train”. This concept is seen as fundamental to designing successful SUDS schemes – with drainage techniques in series incrementally reducing pollution, flow rates and volumes of runoff.

At a city scale, local authorities should ensure SUDS and drainage principles are integrated into planning policy.

At the neighbourhood and site scale, SUDS should be implemented in the most appropriate way according the local context and existing landscape features.

Hopwood Park motorway service area was developed with a strong SUDS system as the basis for the scheme design and provides a good working example of such techniques. Jamshedpur in India uses a simple rainwater harvesting system to provide water for washing and flushing toilets, and provides a good example of using SUDS to cope with water scarcity.

Encouraging the use of SUDS through local planning policy provides a good basis for establishing more sustainable drainage patterns based on green infrastructure.

Priority: manage surface water and flood risk
Tags: water, regions and subregions, cities and towns, neighbourhoods