Urban water trading–hybrid water systems and niche opportunities in the urban water market–a literature review

The integration of hybrid water systems (HWS) into the traditional supply networks is closely linked to achieving sustainable water provision for ever-expanding urban developments. These systems aim to utilise locally occurring water sources by collecting and using water within a discrete boundary. Alternative water technologies such as greywater and rainwater collection systems can reduce pressure on shallow groundwater resources, lessen infrastructure and maintenance costs of existing water systems by deferring new developments such as seawater RO desalination plants and wastewater treatment plants. Ultimately, large-scale HWS implementation can bring about the creation of a water trading market, either in the form of physical peer-to-peer water trading or via a credit-debit system. This review highlights the social, technical and administrative components and factors involved in establishing sustainable HWS. It describes traditional and future trends in urban water management, that is now guided by Water Sensitive Urban Design and Integrated Urban Water Management approaches. The technical aspects of HWS’, their components, benefits and drawbacks of their implementation are highlighted. Social implications from the viewpoints of water practitioners as well as consumers are discussed. An overview of the economics of hybrid water systems, both in terms of their cost and energy consumption per water unit is provided. Sections on the role of policy makers and governance arrangements for small-scale distributed water systems and an overview of the current status of rural and urban water trading schemes conclude the review. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.