SuDs – the long wait for implementation is over

After a delay of 13 years, mandatory sustainable drainage systems (SuDs) in new developments will be implemented via Schedule 3 of the Flood and Water Management Act 2010 (Schedule 3) in 2024.

In doing so, we are pleased to note that the government has accepted AXA UK’s proposal for SuDs (in new developments in England) as a solution to reduce the risk of surface water and sewerage flooding.

The call for SuDs is part of a suite of recommendations to improve the sustainability, safety and resilience of the built environment, contained in AXA UK’s report – “Building for the future: A roadmap to sustainable development”. The report, to which our Partner, Paul Lowe contributed, was published in October 2022. It was then sent to the Secretary of State for Levelling Up, Housing and Communities in December 2022 as part of an appeal from construction industry experts for implementation of Schedule 3.

The enactment of Schedule 3 is welcome news given the significant increase and severity of surface water flood claims in the last decade. The occurrence of surface water floods are hard to predict which accounts for their increased risk profile.

Climate scientists have calculated that the number and severity of surface water floods (known also as flash floods) will increase further due, partly, to the rise of sudden, heavy rainstorms as a result of climate change.

These sudden deluges, together with the impact of urbanisation and a growing population, are also overwhelming our traditional drainage systems (built in the Victorian era) and exacerbating the issue. Research conducted by Locktons indicate that the growth of housing developments in the last century has led to London’s drainage systems currently working 80% over capacity.

Unlike traditional drainage systems, SuDs are designed to manage the water runoff from properties and developments created by surface water floods. They do so by slowing and holding back water flow whilst allowing pollutants to be broken down through natural processes via permeable surfaces, wetlands and grassed areas which absorb heavy rainfall. SuDs therefore lower the risk of flooding. At the same time, they offer much needed green space in urban areas.

DEFRA will launch a consultation on impact assessment, national standards and statutory instruments later this year which will consider how Schedule 3 will be implemented, before implementation in 2024.

DEFRA states that Schedule 3 will provide a framework for the approval and adoption of SuDs for the lifetime of a development. However, the drainage system will require approval before any construction work can start.

For construction professionals, the design proposals and build times will need to align with the implementation of new planning policy under Schedule 3.

It may be prudent therefore to provide design advice earlier in the planning process, failing which we may see claims for errors and delays.

Given that SuDs are a fairly new technology, there may be a shortage of specialist designers and contractors familiar with the system. Training will be necessary to try and avoid PI claims (for delay) against designers with no or very little experience of SuDs. Further, consideration will need to be given to the immediate demand and availability of such specialists and accessibility to any specialist materials used.

We may in time see government endorsement and adoption of policy on all other recommendations contained in the AXA UK report. These are:

  • Defining sustainable buildings to provide a point of departure for future building regulations and more ambitious sustainability targets.
  • Introducing financial support measures to help consumers purchase sustainable homes.
  • Establishing incentives for consumers and industry to equip homes and commercial properties with smart devices.
  • Education and training to bolster expert capacity to create safe, sustainable and insurable buildings.

We would like to see the government take up the first recommendation as a next step to ensure regulation is keeping pace with the government’s sustainability ambitions. In particular, the introduction of retrofitting targets or voluntary property benchmarking programmes. We consider that this will:

  1. Assist government with implementation of the National Retrofit Plan
  2. Accelerate the decarbonisation of the built environment and
  3. Encourage a more comprehensive approach to sustainability across the construction sector.


The implementation of SuDs via Schedule 3 is a great example of insurers’ role in instigating awareness and regulatory change and we are proud to support AXA UK in their endeavours.

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