Podcast Episode #4: Sustainable Drainage Systems (SuDS)

Understanding SuDS: What, Why & Where

SuDS are designed to replicate natural drainage processes, offering a more sustainable alternative to traditional underground systems. Andrew encourages listeners to explore the evolving regulations such as the National Standards for SuDS (updated July 2025), and compares England’s position to the journey already travelled in Wales, with concepts such as SuDS Approval Bodies (SABS) being in place.

Guidance highlights how SuDS can deliver multiple benefits, improving water quality, enhancing amenity, and supporting biodiversity, while managing flood risk. Essentially, Engineers/Designers want to mimic nature in providing flood protection through use of SuDS, rather than defaulting to concrete or underground “traditional” drainage in order to provide multiple benefits to water quality and amenity and not just dealing with water volumes.

Commuted Sum Costing: A Persistent Challenge

One of the key barriers to SuDS adoption is the commuted sum, the financial value assigned to assets handed over for long-term maintenance. Paul notes that while designers have tools to cost schemes, inconsistent rates and under-utilisation of software often leave this task to commercial teams. He proposes the development of an online calculator to provide consistent, realistic values for SuDS assets, potentially linked to carbon costing tools to support sustainable decision-making.