There are many challenges that face us as we enter the new millennium, not least the demand for new, sustainable housing and industrial development. One of the difficulties that needs to be resolved for any new development is the drainage of surface water without causing flooding or pollution, and without sterilising valuable development land. This design manual provides detailed technical advice on sustainable methods of water drainage in the UK, putting sustainable development into practice. Conventional surface water drainage techniques can cause flooding, pollution and disruption of the water cycle. A different approach is therefore needed to reach a more sustainable solution. This manual describes current best practice in England and Wales, and sets out the technical and planning considerations for designing sustainable urban drainage systems for surface water (SUDS). Drainage methods inspired by natural processes are introduced, and guidance is given on how the design team should plan, select and design a suitable system. Detailed appendices include an information checklist and worked design examples. A companion volume (C521) discusses similar technical issues surrounding SUDS in Scotland and Northern Ireland, while C523 covers the wider aspects of SUDS best practice, addressing the legislative issues surrounding SUDS and how organisations may work together in employing SUDS.