Across the world, the role and functionality of urban water utilities has evolved over time, in response to urban challenges. The role of the urban water sector in each region has generally begun with water supply, and then been followed by sewerage, drainage, environmental protection, and then water security efforts through the collection of alternative water sources, such as desalination and recycled water. Typically these services have been delivered through networks of underground pipes, and publicly inaccessible treatment facilities.

Increasing pressures from climate change, population growth, urban densification and urban sprawl require water utilities to adapt and innovate, in order to maintain service delivery standards. These pressures are contributing to a variety of challenges, particularly urban flooding, and sewage overflows (for cities that have combined stormwater and sewerage systems). Upgrading the capacity of existing underground pipe networks to accommodate for increasing stormwater and sewage flows is very expensive. Therefore water utilities are showing increased interest in a variety of multi-functional green infrastructures, across the public and the private realms, to treat, direct and retain water within urban landscapes.

Multi-functional green infrastructures, such as wetlands, swales, raingardens, water squares and green roofs, are associated with a number of different ideologies including: Nature-Based Solutions, Water Sensitive Urban Design, Climate Change Adaptation, Sustainable Urban Drainage Systems and Integrated Urban Water Management. Drivers and designs for multi-functional green infrastructure vary between regions, but a common theme between them is that they have the added benefit of also increasing amenity and greenery within urban landscapes.

The aims of the current research are to provide an initial exploration of the role that water sectors are currently playing in relation to liveability and urban greening interventions, and what potential role they can and should play in this agenda into the future.

This is approached through conducting descriptive case studies on Barcelona, Rotterdam, Amsterdam, Copenhagen and Melbourne. These cities were selected on the basis of the following criteria: a mix of drought and flooding concerns; a record of innovative projects and initiatives; presence in international literature; and participation in international city networks such as 100 Resilient Cities, C40, and Green Surge. Information was collected through interviews with 45 stakeholders