On 28 May 2026, the Environment Agency implemented a major update to its Flood Map for Planning service by integrating climate-adjusted surface water flood risk data directly into the system. This release marks the third significant overhaul of the agency's digital mapping infrastructure in just over a year, following the launches of the new National Flood Risk Assessment and expanded climate layers for rivers and the sea. The update represents a critical shift in how pluvial flood risk is scrutinised during the development process, effectively elevating surface water from a localised drainage detail to a primary planning constraint.
The key change in this update is the introduction of two brand-new datasets: surface water flood risk extents with climate change, and comprehensive banded depth layers for both present-day and future scenarios. The new climate change extents are modelled against the upper-end ninety-fifth percentile allowance for the 2070s epoch, which covers the years 2061 to 2125. Alongside these extents, the new banded depth layers provide specific water depth data across seven distinct categories, ranging from under 150 millimetres up to more than 2,300 millimetres, evaluated across multiple annual exceedance probability events. Coinciding with this release, the Environment Agency has officially retired the Check Your Long Term Flood Risk datasets for development planning purposes, meaning they are no longer considered suitable for supporting planning applications.
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This update is highly important for the industry because it establishes a strict, precautionary time horizon for surface water that aligns perfectly with existing river and coastal climate change guidance. Because the new mapping utilises the conservative ninety-fifth percentile climate allowance, many development sites that previously screened out of pluvial risk will now find themselves sitting within a formally mapped surface water flood pathway or low spot for the first time. Furthermore, the shift from probability-based data to explicit depth bands gives flood risk consultants and local authorities much clearer data regarding the actual severity of potential flooding, allowing for a more accurate evaluation of hazards to people and property.
For live and upcoming planning applications, this immediate transition has immediate consequences on the ground. While standard river and sea Flood Zones remain unchanged, any site that now falls within a newly mapped surface water risk area may instantly trigger the requirement for a site-specific Flood Risk Assessment or a dedicated surface water technical addendum, even if the project is located entirely within Flood Zone 1. Under current planning practice guidance, these new layers mean that surface water must be fully weighed within the Sequential Test framework, potentially forcing developers to revise their site layouts, raise finished floor levels, or completely redesign their sustainable drainage strategies to satisfy local planning authorities. Practitioners and developers are advised to immediately remove the legacy long-term risk layers from their internal GIS systems and transition to the live data feeds hosted on the Defra Data Services Platform to ensure all active designs reflect these new statutory standards.
[Main image credit: Jun Huang / shutterstock.com]