Planning for Flood Risk: The NPPF Explained

How the NPPF came about

Before 2012, national planning policy was spread across dozens of detailed documents known as Planning Policy Guidance notes (PPGs) and Planning Policy Statements (PPSs). For flood risk, PPS25: Development and Flood Risk (2006) was the key reference, introducing the familiar Sequential and Exception Tests still used today.

When the NPPF replaced this patchwork of policies in 2012, it aimed to simplify the system and promote sustainable growth. It has been refined several times since — most recently in December 2024 — with each update reflecting new priorities around design quality, infrastructure, and climate adaptation. Those changes build on wider developments in flood and water management legislation, including the Flood and Water Management Act 2010, which remains central to how local authorities and Lead Local Flood Authorities (LLFAs) manage risk.

Flood risk at the heart of decision-making

The NPPF’s approach to flood risk is clear: steer development towards the safest locations first. Local authorities and applicants are expected to apply a Sequential Test to guide new proposals to areas with the lowest probability of flooding, and use the Exception Test where development in higher-risk zones can still be justified.

This risk-based framework is supported by the Planning Practice Guidance (PPG), which sets out how to assess flood risk from all sources — not just rivers or the sea, but also surface water, groundwater and drainage. The 2025 update to the PPG places greater emphasis on this broader assessment, requiring clearer evidence and stronger reasoning when development falls within or near mapped risk areas.

These national expectations align with the role of the Environment Agency, which advises on flood zone mapping, permits and site-specific planning guidance, including flood risk activity permits and the management of main rivers and ordinary watercourses.

Applying the Sequential or Exception Test properly ensures that site selection and design respond to actual flood risk, reducing the chance of delay or objection during the planning process.

The role of the Flood Risk Assessment

For any development in Flood Zones 2 or 3, or in areas of critical drainage within Zone 1, a Flood Risk Assessment (FRA) is mandatory.

An FRA identifies all potential flood sources affecting a site and demonstrates how risk will be managed. It needs to address flood levels, climate change, surface water flow routes, safe access and egress, and emergency procedures. A well-prepared assessment also considers how ground levels, landscaping, and drainage design can minimise risk both within and beyond the site boundary.

Early commissioning of a detailed Flood Risk Assessment allows design and engineering teams to plan site levels, building thresholds and infrastructure connections around the identified risks — often improving both planning outcomes and build efficiency.

Emerging datasets such as NaFRA2, the Environment Agency’s latest national flood risk model, are improving the consistency of evidence available to support both strategic plan-making and site-specific assessments.

Sustainable drainage as standard practice

The NPPF links closely with the new 2025 National Standards for Sustainable Drainage Systems (SuDS), which establish SuDS as the default approach for managing surface water in new development.

Designers are now expected to show, from concept stage, how SuDS principles have been integrated — using natural processes to slow, store and filter runoff, while delivering benefits for biodiversity and amenity. Local planning authorities and LLFAs assess drainage proposals against these standards, requiring clear evidence of long-term maintenance and performance.

This renewed focus reflects the government’s growing investment in flood resilience — from the £7.9 billion infrastructure programme to the £10.5 billion flood defence funding overhaul. Together, these demonstrate how sustainable drainage is becoming inseparable from wider resilience planning and national infrastructure strategy.

In practical terms, surface water management should now form part of every site’s early design development. A well-structured surface water drainage strategy can resolve multiple challenges at once — balancing runoff rates, water quality, biodiversity and landscape value within a single coordinated design.

Implications for planning and design teams

For developers, architects and planners, the NPPF provides both a framework and a warning. Flood risk and drainage are now key tests of sustainable development — and proposals that fail to address them thoroughly can struggle to gain consent.

Successful schemes typically:

• Integrate flood and drainage evidence at the site selection or concept design stage.
• Provide a clear, defensible sequential rationale in the planning statement.
• Present a proportionate, data-driven Flood Risk Assessment and SuDS strategy.
• Coordinate between architects, engineers and flood consultants from the outset.

These principles apply equally to large housing schemes, smaller infill plots and individual household projects within mapped risk zones. Local planning authorities are also becoming more consistent in how they assess such proposals, reflecting closer collaboration between LLFAs, drainage boards and the Environment Agency, as highlighted in the role of Lead Local Flood Authorities and Internal Drainage Boards.

Policy, funding and future direction

Flood management policy in England continues to evolve. Major investment commitments — including the £10.5 billion national defence programme — are now aligned with planning policy through the NPPF’s focus on resilience and infrastructure delivery. Further support has been announced through an additional £2 billion boost to the UK’s flood defences, building on the lessons of recent flood events and insurance data.

The introduction of the 2025 National Standards for SuDS, the growing emphasis on local planning authority responsibilities for flood and SuDS, and continuing debate around housing growth and flood risk all point towards a more joined-up and climate-aware planning system.

Advances in forecasting, such as the Met Office’s role in flood management, are also improving how risk is predicted and communicated — giving local authorities and developers better tools to plan, adapt and respond.

Building with climate in mind

The NPPF is a living framework, updated as new data and climate projections emerge. Its continued emphasis on flood resilience — from national investment through to site-specific design — makes it clear that sustainable development in England must now take account of a changing climate at every scale.