Sustainable Drainage is a new environmentally friendly way of dealing with surface water runoff which avoids the problems associated with conventional drainage practice. Conventional drainage exacerbates flooding, causes pollution and is generally more expensive to install and to maintain than Sustainable Drainage schemes. Sometimes referred to as Source Control and as Sustainable Urban Drainage (hence the acronym SUDS), in fact this is a design approach which is equally applicable to rural and urban sites.

The Environment Agency in the UK advocates Sustainable Drainage schemes because they do not contribute to flooding, they encourage wildlife and provide visually attractive, and educational, amenities in the form of wetland habitat which is increasingly under threat in the UK. Currently, the Environment Agency has two demonstration sites; one at the M40 Motorway Services Area in Oxford and another at the Hopwood Motorway Services Area on the M42. Robert Bray Associates has been consultant on both these innovative projects.