Welsh Sustainable Drainage System (SuDs) Regulations coming into force

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Everyone concerned with building and development in Wales should be aware of new laws relating to sustainable drainage systems (SuDs) that will come into force on 7 January 2019.

SuDs deal with the management of surface water (i.e. rainwater) in a way that is intended to mimic natural processes, rather than removing the water via traditional underground piped drainage. SuDs consist of a network of drainage components (e.g. swales, ponds and basins) which seeks to control surface water close to where it falls and slow down and reduce runoff. SuDs are considered more environmentally friendly and sustainable than conventional piped drainage, and help to tackle flooding and pollution through the slowing down of run-off.

As matters currently stand in Wales, whilst Welsh Government policy encourages the implementation of SuDs and local planning authorities (LPAs) will sometimes require that SuDs are provided as part of a development by way of planning conditions and/or section 106 agreements, there is no statutory obligation on developers to provide SuDs as part of their development proposals. However, this will change from 7 January 2019 when a new regime comes into effect in Wales with the implementation of Schedule 3 of the Flood and Water Management Act 2010 and associated Regulations. These new laws:

  • Prohibit the commencement of any construction work “which has drainage implications” (i.e. where the building or structure to be constructed will affect the ability of the land to absorb water) until a SuDs system has been approved by a SuDs Approving Body (“a SAB” – which will be a new body within each of the Welsh unitary authorities). Applications for approval can either be made as a free-standing application to the SAB or, where the construction work requires planning permission, the application can be combined with the application for planning permission (note however that it is, nevertheless an entirely different approval process to that of planning permission). To obtain approval, the developer will need to show, among other things, how the SuD system complies with new National Standards for Sustainable Drainage and provide a maintenance plan and funding mechanism for the system proposed. These Standards set out the minimum design criteria for SuDs and state how they should be built, maintained and operated. If the proposed SuD system does not meet those National Standards, then the SAB will refuse the application and the developer will not be able to commence construction work.
  • Allow the SAB to grant approval for the SuD system subject to conditions. For example, these may relate to the construction of the SuD system such as requiring it to be built as per the approved design, and require the developer to provide a non-performance bond.
  • Give enforcement powers to SABs and, in certain circumstances, local planning authorities, to be used where there has been a breach of the requirement for approval (e.g. construction work has commenced without approval, or a condition of approval is breached, or construction work does not conform to the approved proposals). These enforcement powers include powers of entry, the issue of stop notices (i.e. requiring construction work to stop) and enforcement notices (i.e. requiring the developer to take steps to remedy the breach). A person who fails to comply with a stop notice or enforcement notice, or who wilfully obstructions an authorised person exercising its powers of entry, will commit a criminal offence and be liable to a fine. There is, however, a right of appeal to the Welsh Ministers that can be pursued if appropriate.
  • Once the SuD system has been constructed and the SAB is satisfied that it functions as per the approved proposals and any conditions of approval, then, with the exception of some specific types of development (e.g. where the SuD system serves a single property which is controlled by a single person or two or more persons together or any part of the SuD system which is a publicly-maintained road), the SAB must adopt the SuD system. This means that the SAB will become responsible for maintaining the system in future, and it is highly likely that an adoption agreement will need to be entered into between the developer and the SAB dealing with matters relating to the adoption such as the funding of maintenance costs and access rights to the system for the SAB. A SAB may either adopt the system of its own accord, or at the request of the developer. A SAB may also adopt a drainage system voluntarily even where the duty to adopt doesn’t apply, for example an existing drainage system which hadn’t been subject to approval.
  • Makes the right to connect surface water to a public sewer conditional on the drainage system being approved by a SAB.

There are, however, a number of exceptions to the requirement for SAB approval. In the following instances, developers will not need to seek approval for its SuDs and, provided it is not required pursuant to a planning condition or agreement, will not be required to construct a SuDs as part of their development:

  • Where planning permission was granted or deemed to be granted (i.e. subject to permitted development rights), or where a local planning authority has received a valid application for planning permission, before 7 January 2019. Where planning permission was granted before 7 January 2019 and was subject to a condition as to a reserved matter, then the exception to the requirement for SAB approval will not apply unless an application for approval of the reserved matter is made by 7 January 2020.
  • Where the area covered by the construction work is less than 100 square metres, regardless of whether or not planning permission is required.
  • The construction of a single dwelling house where the area covered by the construction work is less than 100 square metres.
  • Work requiring development consent as a nationally significant infrastructure project.

Furthermore, construction work is not considered to have drainage implications, and therefore not require SAB approval, where the work is carried out by an internal drainage board or is carried out for the purpose of or in connection with a road for which the Welsh Ministers are the highway authority or a railway by Network Rail.

It should be borne in mind that the introduction of the statutory scheme under Schedule 3 of the Flood and Water Management Act 2010 applies to Wales only. In England it has been decided not to implement these provisions and to make provision for SuDs through existing planning mechanisms such as planning conditions and section 106 Agreements. It remains to be seen whether the adoption of the statutory system in Wales will facilitate the creation of a slicker process for the approval and adoption of SuDs systems and whether local authorities and the development industry will collaborate to adopt model forms of conditions and agreements to cut down time spent in negotiation on a scheme by scheme basis.

If you require any advice relating to your legal requirements in respect of SuDs, please contact Huw Williams or Natalie Harries.

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Content Contacts


Huw Williams


Consultant, Cardiff

+44 (0)29 2039 1765


Natalie Harries


Solicitor, Cardiff

+44 (0) 29 2039 1763