Sustainable drainage systems mimic the natural drainage of rainwater from development, through the use of materials and techniques designed to free up capacity in piped drainage and sewers, and so reduce flood risk. They take various forms, for slowing down surface water runoff: from permeable paving or road surfaces and green roofs to green infrastructure in the form of ditches, swales and ponds.

Existing policy

While Government policy encourages all developers to use SuDs, the Government estimates that only 40 per cent of new developments and re-developments are drained by SuDs. There are not currently any legally binding obligations on developers to incorporate SuDs in development schemes, although this has been recognised as best practice for many years. Historically, SuDs have been best secured by planning consent conditions or by planning obligations under Section 106 agreements, and generally under planning policy through local plans and other local planning documents. So, we find the National Planning Policy Framework (NPPF) emphasises the value of SuDs as part of an overall theme of achieving sustainable development through the planning process. It places importance on the sequential, risk-based approach to avoid development in areas at risk of flooding and states that local plans should be supported by a strategic flood risk assessment, to manage flood risk.

Pitt Review

After the devastating floods of the summer of 2007, Sir Michael Pitt conducted an independent review of the cause of flooding and found that two-thirds of the 55,000 properties flooded were affected by surface water runoff which had overloaded traditional (or non-existent) drainage systems. His report recommended action by Government specifically to determine which organisation should own and maintain SuDs and that the automatic right to connect surface water runoff and new developments to the sewerage system should be removed.

Flood and Water Management Act 2010

The enactment of the Flood and Water Management Act 2010 in April of that year takes on board those recommendations in the Pitt Review. As part of a more comprehensive approach towards preventing flooding, Schedule 3 of the 2010 Act imposes a requirement for drainage systems to comply with National Standards on SuDs, which will set out how drainage systems are to be designed, constructed and maintained. Schedule 3 will be supported by regulations and orders, and the National Standards will be accompanied by detailed guidelines.

Key provisions

The key provisions in Schedule 3 of the Act are as follows. A SuDs approving body (SAB) is to be created in all unitary or county councils. The SAB will be given power to approve drainage systems for managing rainwater in new developments, before construction starts. The Secretary of State is obliged to publish National Standards for design, construction, operation and maintenance of SuDs and SABs will have to approve drainage systems that they judge to comply with those National Standards. SABs will be required to adopt and maintain approved SuDs, if they serve more than one property and where the SuDs system functions, as it has been approved at design stage.

The Act also amends the Water Industry Act 1991 to make the right to connect surface run-off to public sewers conditional on the drainage system being approved by the SAB. Sewage undertakers, Environment Agency, internal drainage boards, British waterways and highways authorities will all be statutory consultees to the SAB.

Approval process

Schedule 3 of the Act will impose a requirement on developers to obtain approval of a drainage system for any construction work that will, or is likely to, affect the ability of land to absorb rainwater. SABs will have the responsibility to review and approve (or refuse) applications for approval of a drainage system. The SAB for each area will be the unitary authority, or if there is none, the county council for that area. There will be scope for the Secretary of State to appoint a different body as approving body, in any specified area.

The application for approval of a drainage system will be made jointly with a planning application to the local planning authority, or alternatively may be made as a freestanding application direct to the SAB. It is hoped that the joint application route will encourage discussions between the developer, the SAB and the local planning authority in order to facilitate the design of SuDs. In any event, the planning authority will be required to consult with the SAB in deciding the planning application, and inform the SAB of its decision on that application.

Upon granting approval, an SAB will be able to impose conditions relating to the construction of the drainage system and inspection, and require a performance bond. Fees will be charged for applications to approve a drainage system, and these will be provided for in regulations. There will also be powers and procedures for enforcement for breach of compliance with provisions, where construction is commenced without prior approval of a drainage system, where conditions of approval are not followed, or where construction does not conform to the approved proposals. The Act envisages empowering SABs with powers of entry and inspection, power to issue notices and powers to impose financial penalties.

Adoption of SuDs

SABs will be under a duty to adopt a drainage system that is constructed as approved. The SAB may also voluntarily adopt drainage systems. Once adopted, SuDs will be placed on the local authority asset register, so that their locations are known and future development can take account of them.

Other related matters

It is worth also noting that the Code for Sustainable Homes will be amended to take account of the National Standards for SuDs. As a transitional measure, Defra has advised that the National Standards will take precedence over any conflicting requirements of the Code.

Also, building regulations (schedule 1, Part H) encourage the use of SuDs by providing for a hierarchy of options for the disposal of rainwater, with the preferred option being to drain to an adequate soakaway or other infiltration systems. These will continue to apply within the curtilage of a property. However, it is Defra’s intention that the National Standards will demonstrate how to apply SuDs outside the scope of existing building regulations, for example beyond the curtilage of a development.

Finally, the 2010 Act makes amendments to the New Roads and Street Works Act 1991, so that roads affected by sustainable drainage systems may be designated as streets with special engineering difficulties. This will ensure that SuDs cannot be interfered with until a plan of works has been agreed between the statutory undertaker and the relevant maintaining authority.

Commencement of the legislation

The relevant provisions of the 2010 Act are not yet in force. Defra’s current Business Plan commits the Government to implementation of all remaining provisions by December 2014. Following consultation in 2012, Defra officials are working with stakeholders to address the issues which were raised, taking into account respondents’ calls for adequate time to prepare for implementation of the new regime. Previously, implementation was due in October 2012, but the Department’s progress report on implementation published in December 2012 indicates that the sustainable drainage provisions will now not be brought into force until sometime during 2014.