Southeast Asia has undergone rapid commercial and industrial development over the past half century, which continues to bring economic stability and prosperity to its inhabitants. The combined impacts of population growth, urbanization, and industrialization continue to put pressure on the natural resources and the environment. At the same time, globalization is another momentous challenge for the region.  Southeast Asian megacities are some of the most dynamic and diverse regions, which are playing a key role in achieving global sustainability. Twelve out of nineteen megacities of the world are located in the region, where highly developed areas coexist with poorly developing areas where large economic growth is expected. The poor quality of the living standards of the latter creates many environmental problems that are major threats to the inhabitants of the region. The Southeast Asian environment has been degraded by the release of industrial and domestic wastes, agricultural and aquacultural chemicals, and pollutants from automobiles. It suffers from water-related disasters, Tsunami, floods, typhoons, etc. In order to deal with these issues an integrated approach from the inhibitants, governments and researchers is essential. The environmental threats arising from the increasing population, overuse of natural resources, industrialization, urbanization, and natural disasters present ever increasing challenges to pursuing sustainable development of the region. Many developed countries such as Japan have experiences of dealing with severe environmental pollution and this publication is the result of building an academic network among researchers of related fields from different regions to exchange information. This book will be an invaluable source of information for all those concerned with achieving global sustainability within the water environment in developing regions, including researchers, policy makers, NGOs and NPOs.