Towards sustainable urban drainage

The issue of sustainable development is now high on the global agenda, but there is still a considerable degree of uncertainty in its definition, let alone implementation. The aim of this paper is to reappraise the provision of urban drainage services in the light of this current debate. The approach advocated is not to strive for the unattainable goal of completely sustainable drainage, rather to actively promote “less unsustainable” systems. To do this requires both an understanding of the long-term and widespread impacts of continuing current practices and an understanding of the implications of making changes. Sustainable urban drainage should: maintain a good public health barrier, avoid local or distant pollution of the environment, minimise the utilisation of natural resources (e.g. water, energy, materials), and be operable in the long-term and adaptable to future requirements. Three strategies are proposed that can be carried out immediately, incrementally and effectively and these are to reduce potable water “use”, to reduce and then eliminate the mixing of industrial wastewater with domestic waste, and to reduce and then eliminate the mixing of stormwater and domestic wastewater. A number of techniques are described which may allow adoption of these strategies, many of them small-scale, source control technologies. An incremental approach containing both high-tech and low-tech answers to appropriate problems is the most likely to be implemented but each case must be decided on its merits.