Despite the social goals of sustainable development, including the alleviation of poverty, sustainable engineering approaches have been largely limited to technical measures, promoting engineers as purely technical experts. By under-emphasising social factors, this limits opportunities for engineers to address the full spectrum of challenges posed by the sustainable development model. We explain this in terms of the dominant policy response to environmental problems, known as ecological modernisation, which conscripts engineers into reinforcing false boundaries between technology and society. In contrast to the technical focus of engineering under a framework of ecological modernisation, we suggest that engineering can, in fact, be usefully seen as a hybrid socio-technical profession that breaks these boundaries. This point is underlined by the case-study of indirect potable water reuse, demonstrating that the acknowledgement of hybridity can be used to improve engineers' relationships with the societies they serve, and enhance the contribution of the profession to sustainable development.

The switch from intermittent to constant water supply in London in the late nineteenth century has attracted little attention. This article argues that this transition, the basis of the modern water system, was a considerable undertaking. System-builders (London's private water companies) faced a permissive regulatory environment and a population that could be ambivalent about constant water. While the water companies tried to encourage standardization through contract agreements and inspection, their lack of domestic access encouraged technical fragmentation. Local socio-political relations influenced the form of the constant water system, with consequences for future consumption practices.

Although the development of constant water in London has largely been treated by historians as inevitable, this article explores contemporary arguments for and against the constant water system. A case was made for its main competitor, the much maligned intermittent supply. Water company engineers in the nineteenth century in particular argued against compulsory universal constant water, and it was not obvious that the constant system was better than the intermittent. The universal constant water ideal in London arose from a coming together of politics and engineering, facilitated by a (contested) sharing of knowledge, and the linking of a particular conception of social benefit -the alleviation of poverty -with constant water. Hence, constant water was not an inevitable development, but was a response to particular socio-economic conditions.

How engineering in the context of urban socio‐environmental challenges is practically and effectively mobilized has been the subject of some debate. Numerous professional bodies have encouraged engineers to approach socio‐environmental issues through increased engagement with, and accountability to, the public through effective participatory practices. This article presents a close empirical analysis of a major engineering project in London to argue that engineering has a more complex relationship with social, political and environmental conditions than the idealistic participatory conception supposes. In fact, the spatial, technical and economic arrangements of engineering practice may limit the potential for public participation. Through a detailed analysis of the example of the London Water Ring Main (from around 1988 to 1994), this article shows how myriad sometimes conflicting engineering issues and responsibilities interfered with key elements of effective participation. Therefore, although increased public engagement in engineering may be desirable in theory, substantial professional, institutional and political change may have to occur before this is possible in practice.

No abstract