Sustainable Drainage on new developments in Wales | Sewerage Services | Developer Services | Dwr Cymru Welsh Water
Dwr Cymru Welsh Water

Sustainable Drainage on new developments in Wales

Changing the way surface water is managed


On 7th January 2019, the Welsh Government will introduce Schedule 3 of the Flood and Water Management Act 2010.

From this date all new development of more than one building and/or where the construction area is 100m2 or more, will require sustainable drainage systems (SuDS) for surface water.

The SuDS must be designed and built in accordance with Statutory SuDS Standards published by Welsh Ministers and SuDS schemes must be approved by the SuDS Approving Body (SAB) , before construction work begins.

The purpose of this legislation is to ensure that SuDS are considered and utilised to manage surface water.

The destination of the surface water and the method of removal / management is a key consideration. Designs must comply with the differing surface water destination priorities contained within the Welsh Government’s standards.

Our changing role
We will remain a statutory consultee in the town and country planning approval process, and will continue to control any wastewater connections into the public sewer network. We will also be statutory consultee in the SAB process, and will provide comments in relation to surface water drainage proposals, including the impact of any direct or indirect connections or works near to our networks.

Whilst the role of Town and Country Planning and SABs are differing statutory consenting processes, care must be taken to ensure that planning and SAB considerations are both taken into account when preparing a SuDS design.

The SAB will not only be the approving body for SuDS designs, but also the adopting and maintaining body for the new surface water network in many cases. This includes both the SuDS features and the connecting drainage networks which we traditionally adopted. When your development requires SAB consent, Welsh Water will no longer be the default adopting authority for surface water drainage in Wales.

The Welsh Minsters mandatory standards for gravity foul sewers and lateral drains, and mandatory adoption provisions will not change the introduction of Schedule 3. The requirement to secure our consent to connect surface water to the public sewer network is still required, but SAB approval must be in place first.

The Design Guide Sewers for Adoption 8th Edition will not be applicable across the Welsh Water operational area. Our adoption policy with our English operational areas will not change. Mandatory sewer adoption provisions will remain and we will continue to adopt surface water sewers which must be designed in accordance with Sewers for Adoption 7th Edition.


Transition and exceptions from SAB consent
The requirement for SAB approval and adoption agreements for surface water drainage applies only to new developments and is not retrospective.

Existing sites and developments with planning permission granted or deemed to be granted (unless subject to reserved matters – see below), or where a valid application had been received but not determined by 7th January 2019, will not be required to apply for SAB approval.

SAB approval will be required if the planning permission was granted subject to a condition as to a reserved matter, and an application for approval of the reserved matter is not made before 7th January 2020.

SAB approval is not required for:

  • Developments with drainage implications of a single house and the area of land covered by the construction work is less than 100m2 , or
  • In the case of any other type of construction work, the area of land covered is less than 100m2.

Subject to the exemptions from the need for SAB approval, the SAB approves but does not adopt SuDS if the scheme:

  • Serves a single property.
  • Is a publically maintained road (where section 41 of the Highways Act 1980 applies)

Further sources of information