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INDUSTRY VIEWFINDER SuDS approaches
Do you think that Defra’s failure to implement Schedule 3 of the Floods Act to mandate SuDS (in favour of a “planning policy-based approach”) means SuDS is a ‘nice to have’ in new schemes rather than a ‘must have’?
The Government took some ostensibly decisive action following severe fl ooding in 2007, introducing the 2010 Flood and Water Management Act. This requires local authorities to both manage surface water fl ood risk and develop fl ood risk strategies, including for new developments. However, controversially, Defra failed to implement Schedule 3 of the Act, which was designed to require SuDS in developments – and establish SuDS Approval Bodies (SABs) within local authorities to implement schemes. Schedule 3 would also have ensured that drainage systems were designed properly, approved before construction could begin, and had a long-term maintenance plan. Instead, in 2015 Defra introduced a watered-down approach, comprising non-statutory guidelines. SuDS became governed by planning policy guidance (the NPPF) rather than a legal requirement, with local authorities told to “encourage” the use of SuDS. Since 2015, SuDS has been a mandatory “consideration” for all major developments, though is yet to become compulsory for small developments.
Developers are required to utilise a “natural” approach to stormwater management where possible – this means mimicking natural attenuation by managing runoff at or as close to the surface as possible – and as close to source as possible – rather than relying on more traditional drainage methods comprising underground pipework. A key outcome is that surface water becomes a resource onsite, providing benefi ts to the environment – such as biodiversity net gain – and for users in amenity value.
Engineered and proprietary SuDS comprise pre-designed manufactured products, such as hydrodynamic separators, catch pits, geocellular systems and attenuation tanks. SuDS can also form part of a wider green infrastructure approach, incorporating a palette of features such as parks, swales, detention and retention ponds, urban wetlands, blue and green roofs, and rain gardens, all of which not only imitate natural processes but also offer wider benefi ts for residents and the environment alike. These can provide habitats for species and therefore contribute towards a site’s biodiversity net gain (BNG) requirements, and integrate more seamlessly into the landscape. However, they also often require more space, which can be particularly a diffi cult obstacle to overcome in tight urban environments. As technology advances, stormwater management has also evolved to incorporate smart technologies. This can include ‘Internet of Things’-driven sensors installed in drains, pipes, ponds and tanks that monitor water depth, fl ow rates and water quality, and automatic opening and closing valves to prevent overfl ow by redirecting water fl ow and releasing water at controlled rates. Some systems can use weather forecasts and data to predict fl ood risk, react to storms and intense rainfall and subsequently optimise performance and alleviate pressure on the system. At the planning stage, a virtual replica of a drainage system can be created to simulate how the system will react and behave under different weather conditions. Unsurprisingly, these systems often have a high cost attached, and require maintenance and management. Challenges for architects, developers, engineers and landscape consultants include client awareness and understanding of the benefi ts – and limitations – of systems, as can site footprint limitations and budget constraints. Regulation is also arguably not where it needs to be, with many critics agreeing enforcement is too weak and that regulations are not in line with the requirements demanded by climate change. Criticism also targets the lack of regulated maintenance once systems are in place, slow uptake of innovative smart technologies and a failure to update and retrofi t old and outdated infrastructure.
Survey fi ndings: changing strategies In our 2026 survey, we repeated some questions we asked in our 2023 survey of architects, to gauge whether certain thoughts and specifi cations have changed or shifted in the past three years. The fi rst of these was to ask architects whether they’ve been involved with the specifi cation of green stormwater management, green infrastructure, engineered & proprietary SuDS, or hybrid (green plus engineered and proprietary) SuDS. In 2023 the responses had slightly wider variances, swinging from 69% specifying green stormwater management, to 53% specifying hybrid SuDS, with green infrastructure (68%) and engineered & proprietary SuDS (61%) falling in the middle. In our more recent survey responses were more balanced, with the most selected options tied at 64% for both green infrastructure and engineered & proprietary SuDS. Only slightly fewer said they were specifying the remaining two options, which were green stormwater
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ADF APRIL/MAY 2026
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