A new report co-authored by the Infrastructure Policy Advancement (IPA) thinktank, part of Bentley Systems, and Aqua Consultants, with support from British Water, is calling for mandatory sustainable urban drainage systems (SuDS).

The report highlights the ways water companies, local councils and flood authorities can work together to create sponge cities in the UK to reduce the risk of surface water flooding for 4.6 million UK properties . Sponge cities use innovative infrastructure design to absorb, store, and purify rainwater, mimicking natural flood alleviation processes.

The recommendation is being issued alongside the release of a new report analysing surface water – or pluvial – flooding, which is caused by heavy rainfall on impervious surfaces. The report cites that as extreme weather events triggered by climate change have become more common, the risk, regularity and cost of pluvial flooding have all increased.

Mark Coates, vice president of IPA, Bentley Systems and non-executive director at British Water said:

“Surface water flooding can be hugely expensive to clear up, and put the lives of citizens at risk.

“Sponge cities are the only way to mitigate the risk of pluvial flooding. But authorities must act now, as floods are occurring more regularly and becoming more dangerous every year.”

According to the paper, the main focus should be implementing sustainable urban drainage systems (SuDS) and ensuring that they become mandatory in all UK cities and new development projects.

SuDS are an approach to water management that enable greater surface water runoff by mimicking natural drainage systems whilst causing minimal or no detrimental damage to the environment. Building permeable paving, green roofs, rain gardens and retention ponds as part of new developments are all examples of how SuDS can be created. Water companies, flood authorities, and consultants and contractors must share best practice to learn how to deliver better SuDs more quickly and cost-effectively.

Other recommended measures to prevent pluvial flooding include:

• Increase pace and scale of remediation: The Environment Agency should engage with OFWAT and the Local Government Association to explore whether water companies can lead efforts to help flood authorities develop and implement catchment-based plans for faster surface water flood mitigation.
• Launch Schedule 3 of the Flood and Water Management Act: The public consultation for Schedule 3 of the Flood and Water Management Act must be launched promptly so a framework for approving and adopting drainage systems can be created.
• Work with communities: Planning authorities and water companies must engage with schools, community groups, and households to reduce paved surfaces and increase green spaces, helping to alleviate surface water flooding in their local community.
• Integrate water management plans: It is essential that water management plans for towns and cities are integrated and deal with the coordinated development and management of water, land, and the built environment to best alleviate flooding.

Lila Thompson, CEO at British Water commented:

“Due to rapid urbanisation, the water cycle has changed. An increase in concrete paving over planted space and dated sewer infrastructure meeting more rainfall has created the perfect storm for flooding in many urban areas.

"Everything from modern living environments and building techniques, to community outreach and legislation must change if we’re to address the issue of pluvial flooding before it becomes unmanageable.”

“As pluvial flooding impacts so many people, solving the issue cannot happen in isolation. Nations, cities, towns and individuals need to work together to share insight on successful, effective remediation techniques,” added Noel Edmondson, director of clients and partnerships at Aqua Consultants. “It was heartening to see experts from across the globe contributing towards this paper, ensuring that we drew from a broad range of experience. We hope it helps others to proactively prevent flooding rather than simply reacting to it.”

Click here to read the white paper