Dwr Cymru Welsh Water

Sustainable Drainage on new developments in Wales

How are you managing surface water on your new development?


As of 7th January 2019, the Welsh Government introduced schedule 3 of the Flood and Water Management Act 2010.

All new development of more than one building and/or where the construction area is 100m2 or more now needs approval of Sustainable Drainage Systems (SuDS) features for the disposal of surface water. This is to ensure SuDS are considered and utilised to manage surface water runoff as close as possible to the source.

What do you need to do?


The SuDS must be designed and built in accordance with the 'Statutory standards for sustainable drainage systems – designing, constructing, operating and maintaining surface water drainage systems' published by the Welsh Government. The destination of the surface water and the method of removal and management is a key consideration. The differing surface water destination priorities contained within the Welsh Government’s standards should be taken into account.

While the role of town and country planning and SABs are differing statutory consenting processes, you must take planning and SAB considerations into account when preparing a SuDS design.

Once you've designed the SuDS scheme, it must be approved by the SuDS Approving Body (SAB) before construction work begins. The SAB function is being delivered by local authorities, so you’ll need to contact them to arrange this.

The relevant local authority is not only 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. It’s important to note that when your development requires SAB consent, we are no longer the default adopting authority for surface water drainage in Wales.

Our role


We are a statutory consultee in the town and country planning approval process, and control any waste water connections into the public sewer network. We are also a statutory consultee in the SAB process, and provide comments in relation to surface water drainage proposals, including the impact of any direct or indirect connections or works near to our network of assets.

The Welsh Government's mandatory standards for gravity foul sewers and lateral drains, and mandatory adoption provisions does not interact with schedule 3 of the Flood and Water Management Act 2010. You still need to secure our consent to connect surface water to the public sewer network, but SAB approval must be in place first.

The Design Guide Sewers for Adoption 8th Edition is not applicable across the Welsh Water operational area. Our adoption policy with our English operational areas has not changed whereby mandatory sewer adoption provisions remain and we continue to adopt surface water sewers designed in accordance with Sewers for Adoption 7th Edition.

When is SAB approval not required?


You do not need to get SAB approval if:

  • Your development has 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)

Want to find out more?


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