Section 4 Sustainable Drainage Systems (SUDS) 4.1 The need for SUDS has been identified due to historic drainage practices combined with rapidly increasing urbanisation, resulting in deteriorating water quality. The inevitable result is that the requirements of environmental legislation, encapsulated by the EU Water Framework Directive may not be met. 4.2 SUDS are therefore mandatory for all new developments. 4.3 SUDS techniques enable a treatment train to be developed assuring both runoff quality and quantity to be addressed. Source Control module enables the Developer to design SUDS systems to provide pollution prevention, as well as source, site and regional control. SUDS feasibility, design and auditing is covered in the Sustainable Drainage Systems training course.