Despite sustained pressure from the drainage industry, Schedule 3 of the Flood and Water Management Act 2010, which would create a statutory approval regime for sustainable drainage in England, remains uncommented. The government confirmed in January 2026 that a final decision on commencement would be made ‘in due course’, having declined a parliamentary amendment to bring Schedule 3 into force during the passage of the Planning and Infrastructure Bill. The practical consequence is that the National Standards for Sustainable Drainage Systems, published by Defra in June 2025 as the first major revision to national guidance in a decade, remain non-statutory. Their requirements are enforceable through planning conditions and Ofwat’s adoption code. These requirements cover seven core standards: runoff destination, everyday rainfall management, extreme event control, water quality, amenity, biodiversity, and whole-life maintenance. However, developers can challenge these requirements, while under-resourced authorities may lack the resources to enforce them consistently.
The adoption route through Ofwat’s Code for Adoption Agreements is now a live commercial pathway for developers and sewerage undertakers. Where a sustainable drainage component meets the design and construction standards set out in the Sewerage Sector Guidance, water companies can adopt it as a sewer, creating long-term maintenance certainty that was previously unavailable for most surface water drainage assets. Developers who engage sewerage undertakers at the pre-application stage, rather than after planning approval, can resolve adoption questions before costly design commitments are locked in.
The Maintenance Funding Gap and Procurement
The 2025 National Standards are explicit that sustainable drainage systems serving more than one property require an appropriate body to adopt and maintain them. The standards do not, however, define who that body is or how the ongoing maintenance is funded. For local flood authorities and highway drainage teams, this ambiguity translates into a practical financial exposure. Drainage assets that meet planning requirements but have no confirmed adopting authority at handover create maintenance liabilities that fall either on the local authority or, eventually, on the sewer network they were designed to relieve. The Chartered Institution of Water and Environmental Management has argued publicly that current policy direction is correct in intent but insufficient in mandate, since planning conditions for sustainable drainage are commonly challenged by developers, and local authorities cannot always defend them.
The AMP8 investment programme is creating procurement conditions that favour early adoption planning. Where water utilities are commissioning storm overflow reduction schemes that incorporate green infrastructure, they are increasingly specifying long-term maintenance arrangements as a condition of contract. Engineering firms and drainage contractors who can demonstrate a route to adoption, whether through the Sewerage Sector Guidance pathway, a Section 104 agreement, or a local authority maintenance agreement, are better positioned in a procurement environment where asset lifecycle costs carry growing commercial weight. Urban Drainage UK 2027 examines how adoption frameworks are evolving, what the 2025 National Standards require in practice, and how water utilities, developers, and local authorities are structuring sustainable drainage procurement to achieve maintenance certainty across the asset life.
