Sustainable Drainage Systems (SuDs) are a mandatory legal obligation for new developments in Wales.


The majority of new development schemes must be approved by a SuDs Approving Body (SAB) (the local authority) before any construction work occurs on-site. Proposals are subject to Schedule 3 of the Flood and Water Management Act 2010, as well as considerable supporting guidance from both the Welsh Government and other statutory bodies. The key features of schemes are water quantity, water quality, amenity, and biodiversity.

Source control is a major consideration, with infiltration, especially swales being the first option in how best to control the surface water drainage.

It is critical that developers adhere to this legislation as SABs have been granted enforcement powers, with failure to comply being considered a criminal offence and liable to hefty fines of up to £20,000.


SABs are responsible for adopting the SuDs system, if required. The hope is that SABs will better understand the cumulative impact of SuDs and that developers could extend existing systems to incorporate additional developments rather than creating new systems.


SuDs legislation doesn’t make any provision for a legal agreement dealing with maintenance of SUDs.

This means that there are likely to be vast differences in the kinds of legal agreements that developers are required to enter into across Wales. Currently there isn’t any “precedent” legal agreement and the types of provisions are likely be unique to each particular drainage system or development. Geldards have been at the forefront of developing precedents that are now beginning to be commonly used.

We have been at the forefront of this emerging legislation and have significant experience dealing with all the potential stakeholders in SuDs planning, approval, adoption, maintenance, management companies, property owners, local authorities, highways authorities and Welsh Water. We can help support you to put agreements in place to cover every eventuality.

We can also help you if matters become contentious, with an ability to advise on appeals against SAB determinations and SAB enforcement. We recently succeed in representing a client at the very first SAB enforcement appeal.

Related expertise include: Compulsory Purchase & Compensation, Highways, Infrastructure, Planning & Environmental, Regeneration & Development.

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