The Maghreb region is among the poorest in terms of per capita water availability. This shortage constitutes a potential threat to socio-economic development and ecosystems. Admittedly, the millennia-old management of water resources in the Maghreb has allowed the maintenance of a balance, still precarious, between population and natural resources, but with the modernization of production systems and water management networks, local know-how has been overturned in favor of the adoption of new management techniques that are often poorly assimilated by users, and this balance is currently threatened.The colossal effort to mobilize water resources undertaken by the Maghreb countries, which is becoming moreover conflicting, must imperatively be accompanied by a no less important effort to supervise farmers and to improve water efficiency. The losses of output of the distribution networks are enormous, and the efficiencies of water use are low for agricultural and industrial water. In this book, the status of water use and measures to improve these efficiencies are extensively discussed.