Planning for Flood Risk: The NPPF Explained

The National Planning Policy Framework (NPPF) is the document that decides how flood risk is handled when land is developed in England. It tells councils to keep new building away from the places most likely to flood, to test the alternatives before allowing anything in a higher-risk area, and to make whatever is built safe for its lifetime. This guide explains how NPPF flood risk policy works, where it sits in the planning system, and what it asks of anyone bringing a site forward, updated for the rewritten Framework that took effect on 17 August 2026.

The Environment Agency estimates that 6.3 million properties in England are already at some risk of flooding, and that this will rise to around 8 million, roughly one in four, by the middle of the century.

What is the NPPF, and where does flood risk sit within it?

The NPPF is the government's planning policy for England. First published in 2012 and rewritten in August 2026, it sets out what local planning authorities should approve, refuse and ask for when they decide applications and prepare local plans. Flood risk now has a chapter of its own. Chapter 18, "Managing flood risk and coastal change", contains nine policies, F1 to F9, with the flood zone definitions and the vulnerability classification held in a new Annex F.

The Framework does not work alone. It is read alongside the Planning Practice Guidance (PPG), which explains how to apply the policy in practice, and it sits on top of wider law such as the Flood and Water Management Act 2010, which gives Lead Local Flood Authorities their role in surface water. The NPPF applies only in England; Wales runs its own system through TAN15. What ties the whole chapter together is a single objective, stated at the top of it.

How did we get here? From PPS25 to the 2026 rewrite

Flood risk policy has moved through three main stages, but its core idea has held steady for twenty years: steer away from risk, test the alternatives, then make development safe. What has changed is where the policy lives and how firmly it is worded.

The August 2026 rewrite is the largest of these. It pulled the flood zone definitions and the vulnerability tables into the Framework itself, and it changed the tone from "development should only be allowed where..." to "should be refused unless...". For a clause-by-clause account of every change, see our guide to the NPPF August 2026 changes for flood risk and drainage. The rest of this page explains how the framework works as a whole.

How the NPPF steers development away from flood risk

The NPPF applies a sequence, not a single test. A proposal is first steered towards the safest available land (avoidance). If it still falls in an area at risk, the sequential test asks whether there is a reasonably available site at lower risk. For flooding from rivers or the sea, the exception test then asks whether the benefits justify building there anyway. Whatever is allowed must be made safe for its lifetime (policy F7) and drained sustainably (policy F8).

The sequential test (policy F5) aims to steer development to areas with the lowest risk of flooding from any source. Its area of search is now capped at "the anticipated catchment of the development in terms of its likely occupiers or users", which stops a small local scheme being asked to look borough-wide for alternatives. The Framework also added a surface-water-only exemption: where a site is at risk from surface water alone, the test falls away if the flood risk assessment demonstrates clearly that the layout and design keep people safe for the development's lifetime without increasing risk elsewhere.

The surface-water exemption places real weight on the flood risk assessment: it is the FRA, not the sequential test, that now has to prove a surface-water site is safe.

The exception test (policy F6) applies to flooding from rivers or the sea in Flood Zones 2, 3a and 3b. It now has three parts, all of which must be met: the development must provide wider sustainability benefits that outweigh the flood risk; be safe for its anticipated lifetime; and not increase flood risk elsewhere, reducing it overall where possible. Which uses can go in which zone is set by the flood risk vulnerability classification in Annex F, which now states plainly that incompatible development should be refused.

When do you need a flood risk assessment?

A site-specific flood risk assessment must accompany all development in Flood Zones 2, 3a and 3b, whatever the size of the scheme. In Flood Zone 1 it is required in defined cases, which the August 2026 Framework widened.

• Flood Zone 2 or 3: an FRA is needed for any proposal, from a single dwelling to a housing estate.
• Sites of one hectare or more: an FRA is needed even in Flood Zone 1.
• Critical drainage areas: land the Environment Agency has flagged for drainage problems needs an FRA.
• At risk from any source: since August 2026, any Zone 1 land shown at risk from any source, now or in the future, needs an FRA, with the old "more vulnerable use" qualifier removed.

The report is also a national validation requirement: the Framework's Annex C lists the site-specific FRA among the documents a council needs before it can determine an application, so a missing or weak assessment can hold up or invalidate a submission. An FRA should be proportionate to the site, and it should address every source of flooding, the climate change allowances, safe access and escape, finished floor levels, and the effect of the scheme on land beyond its boundary.

Sustainable drainage: SuDS as the default

Since August 2026, the NPPF requires sustainable drainage systems (SuDS) on all development that could affect drainage, designed to the 2025 National Standards for SuDS, and no longer only on major schemes.

Policy F8 extends the national SuDS standards to minor development for the first time, so an extension or a small commercial scheme is now judged against the same design benchmark as a housing estate.

In practice this means surface water has to be designed in from the concept stage, working down the drainage hierarchy (reuse, then infiltration, then a watercourse, and only then a sewer) rather than defaulting to a pipe. The SuDS hierarchy sets that order, and the standards expect clear evidence of long-term maintenance. Policy F8 also introduced a new rule on watercourses: it discourages putting them in culverts, and encourages removing existing culverts and restoring open channels where possible. Where a scheme could affect drainage, Annex C now expects a statement showing how the national standards have been met.

Flood risk and a changing climate

The NPPF requires flood risk to be assessed over the whole life of a development, which for housing is taken as at least 100 years. That is done using the Environment Agency's climate change allowances, which uplift rainfall and river and sea levels to reflect a warming climate.

The 2026 Framework also strengthened its coastal policies. Policies F3 and F9 now name Shoreline Management Plans and the National Coastal Erosion Risk Map, and they reach beyond formally designated Coastal Change Management Areas to any land likely to face erosion or tidal inundation over the next century. For low-lying and estuarine sites, that widens the range of places where coastal change has to be considered as part of the flood risk picture.

What the NPPF means if you're planning to build

For developers, agents and architects, the NPPF is both a route to consent and a warning: flood risk and drainage are now among the clearest tests of whether a scheme is acceptable, and a proposal that treats them as an afterthought can struggle. The work is easier and cheaper when it is done in the right order.

1. Check the flood zone and every source of flooding early, using the Flood Map for Planning and the council's strategic flood risk assessment.
2. Establish your sequential test position before you commit to a site, so a lower-risk alternative does not derail the application later.
3. Commission a proportionate flood risk assessment at concept stage, while ground levels and layout can still respond to it.
4. Design SuDS to the national standards from the outset, not as a condition to be discharged after permission.
5. Keep the evidence current: cite the F policies and Annex F, not the retired paragraph numbers.

Get those five things right and flood risk stops being the thing that holds a scheme up. If you would like that work handled by chartered consultants, Unda prepares flood risk assessments for planning across England, and can advise on the sequential and exception tests and your surface water drainage strategy at the same time.

Frequently asked questions