Urban Drainage & the Water Environment: a Sustainable Future
FR/R0011
November 2004

This review describes the development of drainage systems in urban areas, from early civilisations to the present day. The earliest drainage systems removed surface water from streets and houses. As cities and towns developed and grew, so did the need for centralised systems of water treatment and supply and, subsequently, the collection, transport and treatment of human waste. Not surprisingly, the enlarged drainage infrastructure incorporated and built upon the former system for surface water drainage. Thus the water carriage system for the disposal of human waste was born.

Whilst a reliable water supply and sewage free streets greatly benefited the public health and made cities and towns pleasanter places in which to live, an unwanted effect was degradation of river water quality which was addressed by the development of treatment plants. The evolution of these plants is described along with the concepts of interceptor sewers, separate and combined sewer systems and combined sewer overflows (CSOs). CSOs are significant causes of stream pollution, but in recent years the development of the Urban Pollution Manual (1) changed the approach to the design of CSOs. The Manual presents a methodology that makes appropriate use of modern tools for analysis of sewer flows and quality together with the characteristics and the required uses of the receiving water - crucial to the achievement of the requirements of the EU Water Framework Directive (2). The importance of this topic is reflected by the fact that the 2000 - 2005 investment programme of the water utilities in England & Wales for reducing/improving intermittent discharges of sewage to watercourses is £1,948M.

The review then considers alternative methods of reducing discharges of urban stormwater to receiving waters by the adoption of Sustainable Drainage Systems (SUDS or SuDS) based on detention basins, retention ponds, wetlands, infiltration trenches and basins, porous paving, swales and filter drains. Examples of their application are provided for both the UK and overseas.

Sustainability is then discussed in the context of UK urban planning, Integrated Urban Water Resources Management (IUWRM) and climate change. IUWRM involves the consideration of technologies to reduce the demand for water (through water conservation measures) and to use water more efficiently (by reclaiming water for re-use). These technologies are described, and it is concluded that the preservation and restoration of our water environment will become increasingly dependent on their implementation to reduce the loadings of wastewaters being discharged to rivers, lakes and coastal waters.

Copies of the full report are available from the Foundation, price £15.00, less 20% for FWR Members.