Highlights • Develops new framework for sustainability based on philosophy of technology and urban studies. • Analysis of the sustainability of different technological developments in urban water systems. • Shows contradictory trends in urban water systems improving and undermining sustainability.

Abstract Water infrastructure is essential for the functioning of modern cities. This paper analyses conventional models of water infrastructure provision and emerging alternatives in order to identify points of reform and resistance in the relationship between people, technology and water in cities. It begins with a review of recent academic contributions to understanding the relationships between people, technology and nature in cities through the analysis of urban infrastructure. The work of Andrew Feenberg, a critical philosopher of technology, is presented as the basis for analysing both the technical and discursive elements of infrastructure. Feenberg's concept of ‘the technical code’ is used to synthesise key insights from the analysis of urban infrastructure and technology, to devise a series of critical categories for comparing changes currently underway in urban water infrastructure provision. This ‘technical discourse of water infrastructure’ is used to analyse developments in desalination, wastewater reuse, decentralised non-potable supply, domestic water efficiency, water sensitive urban design and ecological sanitation. Planners, designers and policy makers concerned about sustainability should be wary of the technical inevitability of desalination, potable recycling and other systems which reinstate conventional codes of domination and control of nature and separation of public concern from technical rationality. Decentralised water systems embody assumptions about the limits to water resources, but can also be problematic as high users of energy and reinforcing a private right to water. Improving the efficiency of domestic water using technologies and appliances is unarguably important in achieving sustainability. Moving beyond water efficiency to open up discussions about water using practices and cultural norms holds greater potential for transforming water consumption. Water Sensitive Urban Design is widely championed by designers and planners as exemplifying a sustainable approach to urban nature, providing a useful foundation for moving beyond drainage into water supply and wastewater technology and discourse. Ecological sanitation is filling a basic necessity in developing cities and may be part of a longer term transition to sustainability in developed cities in the future. Eliminating water from sanitation and recovering resources from waste holds the potential to radically reorder relationships between bodies, urban spaces and nature. Relationships between cities, technologies and water are shifting. The extent to which this balance falls in favour of sustainability over coming decades will be determined by political discourse as well as technical innovation.