Sustainable drainage systems (SuDS)

What are SuDS?

SuDS mimic natural processes and reduce flooding by managing rainfall close to its source and wherever possible at, or near the surface, as opposed to sending it down a drainpipe as quickly as possible.

By building in permeable paving, channels, green roofs, swales, soakaways or ponds, SuDS slow, store and treat water that could cause damage. Well-designed SuDS should wherever possible incorporate the four elements of water quantity, water quality, amenity and biodiversity.

SuDS can be delivered in a variety of urban and rural contexts including housing, schools, community buildings, parks, public open spaces and highways. Incorporating natural processes help make communities greener, more attractive places to live.

If constructed incorporating natural planting including trees, SuDS can deliver extensive wider benefits. These can include enhanced nature incorporation into built environments, for biodiversity, placemaking, human health and wellbeing, air quality, and urban heat island mitigation. They can also filter and provide a level of treatment to the water running into them.

Mainstreaming the use of SuDS

SuDS are not a new approach to drainage but progress in mainstreaming their use – despite extensive evidence of their benefits – has been slow and somewhat frustrated by politics.

The Flood and Water Management Act 2010 established a mandatory process (set out in Schedule 3 of the Act) for incorporating SuDS into new development. In 2015 government decided not to implement this requirement because of perceived cost and practicality barriers.

Our report, A Place for SuDS, set out the evidence-base for this mandatory process being required. Working with Peers in the House of Lords we forced a government review of the effectiveness of the planning system in delivering SuDS and have advocated for improvements to the National Planning Policy Framework and Planning Practice Guidance, which have both been updated since.

As understanding of surface water flood risk has increased, alongside awareness of the extent of sewage pollution from storm overflows, we have convened a cross-sector SuDS and Water Reuse Policy Leadership Group to build consensus on the role for SuDS in sustainable water management. Advised by this group, along with our Urban Drainage Group we have advocated to government and via parliament for considerably wider use of multifunctional SuDS to manage water particularly in urban environments, including through implementation of Schedule 3 in England.

We advised and supported government’s review into implementation of Schedule 3. Read our letter to Prime Minister Rishi Sunak, supported by over 40 other organisations, calling on his government to take this implementation forward.

We are delighted government has decided to implement Schedule 3 in England. We continue to support this through the work of our SuDS and Water Reuse Policy Leadership Group.

Blogs

Read thought leadership articles relating to SuDS:

Reports

Read our research reports setting out the mainstreaming SuDS evidence-base. These have been developed collaboratively with experts from academia, planning, local government, engineering, and water and environmental management.

River water quality and storm overflows: A systems approach to maximising improvement

This report considers how a systems approach encompassing a wide range of solutions and interventions will be necessary to effectively tackle sewage pollution from storm overflows.

A Place for SuDS? Assessing the effectiveness of delivering multifunctional sustainable drainage

Surface water flooding is a growing threat to businesses, critical infrastructure and millions of people across England.

As the Government presses ahead with plans for a million homes, the problem of surface water flooding will increase unless development meets a high standard of resilience. At the moment, though, despite new planning rules, many new homes are built without sustainable drainage. The Government’s current review of SuDS law and policy is a chance to simplify the range of approaches around the country and ensure that new homes are built with natural flood resilience in mind.

This report by CIWEM and WWT sets out new evidence on the quality of sustainable drainage in England and our recommendations for increasing uptake and upkeep of SuDS in a quick, affordable way.

A Place for SuDS? is supported by the Wildfowl and Wetlands Trust (WWT), Royal Town Planning Institute (RTPI), Royal Institute of British Architects (RIBA), Institution of Civil Engineers (ICE), Institution of Environmental Sciences (IES), Landscape Institute, University of Exeter Centre for Water Systems, Susdrain, Future Water Association,Association of Drainage Authorities (ADA), Cornwall Community Flood Forum, the Construction Industry Council Champion for Flood Mitigation and Resilience, Royal Society for the Protection of Birds (RSPB), WWF, the Angling Trust, Buglife and Salmon and Trout Conservation UK.

Achieving sustainable drainage: a review of delivery by lead local flood authorities

We are pleased to have contributed to the January 2019 report lead by the Landscape Institute and Construction Industry Council examining how lead local flood authorities are working to deliver high quality, multi-functional SuDS. Further to the Defra and MHCLG review of SuDS implementation through the planning system in England, this review took a wider survey of LLFAs into account.