New town planning

Chris Adair of Marshalls, explores how developers can embed flood resilience into new housing schemes, especially as the UK prepares to deliver over a million homes, including a new generation of towns and communities.

The UK Government’s recent announcement of its plan to build up to 100 new towns, with at least 10,000 homes signals a bold new chapter for the housing sector. Renewed investment in affordable housing and the target of 1.5 million new homes across England over the next five years further add to a construction pipeline for new build properties that is decidedly full
of promise.

Yet, as we build for growth and greater housing availability, we must also build for change. Climate change is no longer just a future risk but a present reality. According to the Met Office, five of the UK’s ten wettest years since records began in 1836 have occurred in the 21st century. The decade from 2011 to 2020 was also 9% wetter than the 1961-1990 average, with winter rainfall up by 25%.

Flooding is already one of the most costly and disruptive climate-related risks in the UK; therefore, as conditions worsen, flood resilience must be designed into these new homes and communities from the outset. The Government’s New Towns Taskforce recognises this, stating one of its goals as being to create “environmentally resilient places that support the Government’s net zero agenda through sustainable design, nature enhancement, low-carbon infrastructure and responsible development, including flood risk mitigation.”

Turning ambition into action

To deliver on this goal, it is imperative that new towns and communities are built with a holistic approach to water management, where sustainable drainage systems (SuDS) form a key part of
green infrastructure. 

While Schedule 3 of the Flood and Water Management Act 2010, which would mandate SuDS in England, is still awaiting full implementation, its principles are already being used in practice. Schedule 3 focuses on managing water runoff in the most natural way possible, slowing down the release of water. This contrasts with more traditional drainage systems, which concentrate
on removing surface water as quickly as possible. 

In addition to reducing flood risk, SuDS can offer broader benefits for developments. They can create more attractive, usable public spaces and support biodiversity, particularly relevant following the introduction of Biodiversity Net Gain (BNG), which became mandatory for most developments in England in February 2024. As a result, SuDS features like rain gardens, swales and tree pits are being used for both flood mitigation and biodiversity enhancements.

Designed for today’s challenges

Rain gardens, in particular, have increased in popularity amongst housing developers in recent years by using plants and soil to retain and slow the flow of rainwater from surrounding hard surfaces. One way to use the rain garden method is by combining it with a kerb, allowing water to flow through an inlet, be slowed down by a diffuser flag, and remain at the surface level to be
absorbed by the soil. This supports plant life and prevents water from entering the sewer system immediately.

Traditionally, incorporating rain gardens into hard landscaping like this, however, has required bespoke detailing, with design teams often needing to adapt standard kerbs or paving to allow
water entry. This bespoke approach has slowed down the process and increased on-site complexity. 

To help solve this, an off-the-shelf system has been developed consisting of three simple elements to make adding rain gardens to a new development easier than ever. 

Combining a left hand inlet, right hand inlet and a complementary diffuser flag, available in a variety of sizes and finishes, it is a true ‘first of its kind’ system which will create both time and cost savings on site when compared to cutting or repurposing standard kerbs. And, due to its modular design, the solution will reduce the margin for error usually associated with bespoke and made-to-measure designs, increasing its effectiveness. 

Resilience that adds value

For developers, incorporating flood resilience features also brings commercial benefits. Homes that are at risk of flooding can be more difficult to insure, harder to sell, and more likely to attract post-occupancy issues. For developers, this can lead to reputational damage and financial liability. Conversely, well-designed SuDS features such as rain gardens and tree pits help define a development’s character, contribute to placemaking and appeal to environmentally conscious buyers.

As the UK embarks on its largest housebuilding programme in decades, the opportunity to create flood-resilient, nature-rich communities has never been greater. By embedding water management into the design and delivery of new homes, developers can reduce risk, add value and meet the expectations of local authorities and buyers alike.

Chris Adair is product innovation manager at Marshalls