ABSTRACT
Water security in many cities across the world is increasingly threatened by the triple pressures of climate change, population growth, and pollution. In response, water authorities have had to look beyond traditional ground and surface waters towards alternatives, such as rainwater, stormwater, recycled water, and desalination. This chapter guides the reader through the diversity of water source options and their associated end uses. A framework is introduced for understanding options available in regard to two factors: “supply resilience,” in the sense of ability to adapt water supply operations to meet water needs regardless of future trends and shocks; and “implementability,” in the sense of being affordable, governable, and acceptable to a community and regulators with environmental and social concerns. Contrasting case studies on Singapore and Melbourne are provided to highlight the difference between water source diversity and water source decentralisation, two concepts that are often conflated. The chapter concludes with a discussion of decision processes for reaching an optimum mix of sources for any given context.
