Flood risk management is no longer driven solely by compliance with drainage calculations. Increasing rainfall intensity, growing development pressures and evolving sustainability requirements are changing how surface water is managed across the built environment. Against this backdrop, Sustainable Drainage Systems (SuDS) are increasingly being treated as critical infrastructure rather than optional enhancements.

While the implementation of Schedule 3 in England remains uncertain, the principles behind it have already shaped the direction of policy and industry standards. The focus is now shifting towards resilience, water quality, biodiversity and long-term asset performance, requiring designers to think beyond minimum compliance and consider how drainage systems will perform in future conditions.

For specifiers and engineers, the challenge is not preparing for a future regulatory change, but designing schemes that can meet the expectations of tomorrow today.

Designing for outcomes, not just compliance

This shift requires a different mindset. Rather than designing drainage systems to satisfy a prescribed approval process, engineers must now design for a set of broader outcomes.

Surface water must be managed as close to source as possible, reducing pressure on downstream networks. Systems should slow, store and treat water, not simply convey it. This reflects the core purpose of sustainable drainage, which is to reduce flood risk, improve water quality and support environmental performance.1

In practical terms, this means integrating attenuation, treatment and conveyance into a single, coherent strategy. Below-ground systems, above-ground features and landscape elements must work together to manage both everyday rainfall and extreme events.

The role of hidden and below-ground solutions

While SuDS is often associated with visible features such as swales or basins, many developments, particularly in urban or space-constrained environments, require a more discreet approach.

Hidden drainage solutions play a critical role here. Systems such as slot drainage, combined kerb drainage and below-ground attenuation structures allow designers to deliver effective water management without compromising site constraints or design intent.

These solutions are particularly relevant where above-ground features are not feasible, or where aesthetics, land take or usability must be preserved. When designed correctly, they can provide the same functional benefits as more visible SuDS components while integrating seamlessly into the built environment.

For designers and contractors, the challenge is to use these systems not as isolated elements, but as part of a wider SuDS strategy that still delivers on water quality, flow control and resilience objectives.

Taking a long-term view of flood resilience

The absence of full Schedule 3 implementation does not reduce the urgency of flood risk management, in fact, it increases the responsibility on project teams to take a proactive approach.

Extreme weather events are becoming more frequent, placing strain on ageing drainage infrastructure and increasing the likelihood of surface water flooding. Investment in flood defences and sustainable drainage remains a national priority, with significant funding committed to improving resilience and supporting innovative approaches.2

For asset owners and designers, this reinforces the importance of specifying systems that are durable, maintainable and capable of adapting to future conditions. Whole-life performance must be considered from the outset, ensuring that drainage infrastructure continues to function effectively over time.

Conclusion

Although Schedule 3 has yet to be fully implemented in England, its influence is already firmly embedded within planning policy and national standards.

For designers and contractors, the message is clear: the industry must move beyond waiting for regulation and instead focus on delivering integrated, future-ready drainage strategies. By combining visible and hidden solutions, and by designing for long-term performance rather than short-term compliance, projects can deliver meaningful improvements in flood resilience today.

References:

1 - https://www.legislation.gov.uk/ukpga/2010/29/schedule/3

2 - https://www.ciwem.org/the-environment/schedule-3-why-we-can%E2%80%99t-afford-to-wait-for-legislation-to-catch-its-tail  

  • Sustainable Drainage (SuDS)

  • Surface water drainage

  • SuDS

Written By

Paul Curtis

Paul has been with Marshalls plc for 24 years, and for the last five, has served as Managing Director of Marshalls Civils & Drainage.

Read Paul's full profile here.