Barnet Council has officially adopted new national standards for Sustainable Drainage Systems (SuDS), a move aimed at enhancing flood risk management, improving water quality, and boosting biodiversity across the borough.
The decision, made by the council's Cabinet on Tuesday, September 15, 2026, sees Barnet aligning with updated guidance released by the Department for Environment, Food and Rural Affairs (Defra) in June 2025. These new standards replace previous guidance from 2015 and provide more comprehensive information for developers, designers, and local authorities. Key changes include a stronger drainage discharge hierarchy with a priority for rainwater harvesting, a mandatory focus on managing everyday rainfall close to the site, dedicated standards for amenity and biodiversity, and requirements for whole-life design, maintenance, operation, and decommissioning.
As the Lead Local Flood Authority (LLFA), Barnet Council plays a crucial role in assessing planning applications that involve SuDS. The adoption of these new national standards will ensure that the council's evaluations are consistent with current best practices and national policy. The new standards are intended for application in the design of surface water drainage systems for new infrastructure and development, whether on greenfield or brownfield sites, and are specifically applicable to 'major development' which is defined as developments of 10 dwellings or more, or equivalent non-residential or mixed development.
Councillor Alan Schneiderman, Cabinet Member for Environment and Climate Change, highlighted that Barnet already incorporates many of the principles found in the new standards through its existing assessment processes. He stated that the adoption would formalise good practice and provide greater certainty for developers. The adoption will provide a consistent and transparent approach to the assessment of sustainable drainage proposals for new developments, offering greater certainty to developers, applicants, consultants, and planning officers. Developers will be required to submit additional supporting information, including enhanced hydraulic calculations and design justification, and to adhere to a stronger drainage discharge hierarchy that prioritizes rainwater harvesting and managing everyday rainfall close to the site. They will also need to consider whole-life design, maintenance, operation, and decommissioning from the outset.
The new standards place a stronger emphasis on delivering multiple benefits through SuDS, including reducing flood risk, improving water quality, enhancing biodiversity, supporting climate resilience, and creating more attractive and multifunctional spaces. This aligns with the council's Corporate Plan and Climate Action objectives.
The Environment Overview and Scrutiny Sub-Committee, which reviewed the draft report, noted the good practice examples of SuDS implementation already present across Barnet, such as in Watling Park, Mill Hill Park, and Cherry Tree Wood. They also recommended that updated guidance be published on the Barnet Council website to assist developers and applicants. Following Cabinet approval on September 15, 2026, officers plan to update the Council's webpages and templates to refer to the new SuDS Standards (2025). A link to the updated guidance will be published on the Barnet website to ensure it is accessible to developers and applicants.
The new SuDS standards include Standard 7, which addresses design for construction, operation, maintenance, decommissioning, and structural integrity. This standard requires a management and maintenance plan to be provided by the designer, supporting the design objectives and ensuring the performance of the SuDS features throughout the lifetime of the development. This plan should advise on parties responsible for maintenance, inspection and maintenance regimes, rehabilitation requirements, and the frequency of maintenance. The standards also emphasize the need for clear access for maintenance and emergency response, and for the design to allow for visual inspection of potential failure points. For SuDS features serving more than one property, an appropriate body will need to adopt and be responsible for maintenance. The LLFA will also include adopted SuDS features within the register of structures likely to have a significant impact on flood risk.
The adoption of the new SuDS standards is not expected to pose any immediate capital financial impacts for Barnet Council. While applicants will be required to submit additional supporting information, including enhanced hydraulic calculations and design justification, these requirements are anticipated to have only a minimal impact on the resourcing requirements of the Lead Local Flood Authority. Existing technical expertise and review processes are considered sufficient to accommodate the additional assessment requirements with only minor adjustments.