Defra publishes updated national standards for sustainable drainage systems
The Department for Environment, Food and Rural Affairs (Defra) has published updated non-statutory standards for the design, maintenance and operation of sustainable drainage systems (SuDS) in England. These standards apply to new infrastructure and development on both greenfield and brownfield sites, excluding retrofit projects and the trunk road network managed by National Highways. The document sets out seven standards that address runoff destinations, the management of both everyday and extreme rainfall and flooding, water quality, amenity, biodiversity, and the design, construction, operation, maintenance, decommissioning and structural integrity of SuDS. The standards aim to assist designers, property developers, local authorities and other key stakeholders—including sewerage undertakers and the Environment Agency—in implementing rainwater management systems that replicate natural processes. Aligned with the National Planning Policy Framework, they are intended to complement broader planning reforms expected later in 2025.