Effectively managing increasingly scarce transboundary water resources in many parts of the world may become one of the most critical challenges facing the international community in the 21st century. Global warming is expected to exacerbate the existing problems of water scarcity in Africa, the Middle East and Central Asia, and threatens to affect even relatively water-secure regions and countries. Global freshwater resources are shrinking at an increasing pace. Forty percent of the world's population depends on transboundary water resources, a situation that raises serious concerns at the international level. Unresolved issues of water resource use and allocation may create the potential for serious interstate conflicts and undermine regional stability. It is imperative that existing and potential disputes over access to shared water resources are resolved through peaceful means within the framework of legal principles and norms provided by international law. While not yet in force, the 1997 UN Convention on the Law of the Non-Navigational Uses of International Watercourses codifies a number of rules of customary law that apply to international watercourses. However, even in the absence of a universally ratified instrument there is a body of international rules widely acknowledged as an authoritative statement of international law governing international watercourses - the International Law Association (ILA) rules on the law of international water resources. The present book, which contains the complete collection of the ILA rules on international water resources, together with comments, explanatory notes and other supporting materials, will be of significant academic and practical value to the range of experts working in this field. There is no doubt that legal scholars and researchers will find this book very helpful in discovering the conceptual underpinings and the evolution of international water law. For the practitioners, this collection will serve as a useful reference tool containing a wealth of 'black letter' normative material.