Efficient and equitable water, wastewater and stormwater management for the megacities is becoming an increasingly complex task. When accelerating water scarcities and pollution in and around urban centres are superimposed on issues like continuing urbanization, lack of investment funds for constructing and maintaining water infrastructures, high public debts, inefficient resources allocation processes, inadequate management capacities, poor governance, inappropriate institutional frameworks and inadequate legal and regulatory regimes, water management in the megacities poses a daunting task in the future. This paper will focus on water management in its totality in megacities, including their technical, social, economic, legal, institutional and environmental dimensions through a series of case studies from different megacities of the world. © 2006 Taylor & Francis.