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Sustainable drainage systems are increasingly seen as a better way of draining urban areas, being ‘more natural’, less resource intensive and offering water quantity and quality control with amenity benefits. Sustainable drainage systems ‘greening’ can also reduce heat island effects. However, little attention has been given to assessing the real value and sustainability of the approach and uncertainties remain over performance and robustness, as well as ownership and maintenance. Received wisdom suggests that sustainable drainage systems have potential to help cope with climate change, while offering wider sustainability benefits over traditional piped drainage. The inherent adaptability of sustainable drainage systems allows them to be implemented incrementally as climate change knowledge advances. This paper provides evidence from a range of initiatives to show how sustainable drainage systems can contribute to a portfolio approach to tackling the problems of climate change. The need for political intervention and enhanced stakeholder engagement to support this type of approach is highlighted.

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The paper reviews the evolution of Hydrodynamic Vortex Separators (HDVS) in the context of application as high rate rotary flow separators for achieving water quality improvements to meet with regulatory requirements in Europe and North America. The types of HDVS and their application for the control of wet-weather discharges such as combined sewer overflows (CSOs), sanitary sewer overflows (SSOs) and stormwater are outlined and a number of myths surrounding their use, dispelled. Reference is made to outputs of peer reviewed comprehensive monitoring, evaluation and demonstration projects on pilot and full-scale installations to demonstrate the efficacy and extensive track record of these systems. Recent developments and innovations in HDVS technologies are discussed, focusing on their combined use as solids liquid separators, contact vessels for wastewater disinfection, the incorporation of self-cleansing screening devices for the control of aesthetic pollutants (e.g. floatables) and the use of computational modelling for optimisation.