This book focuses on sustainable use and protection of transboundary aquifers located along the eastern border of European Union starting from the Baltic Sea and end in the Black Sea. This publication sheds light on a wide range of real problems related to the management of groundwater, problems that are characteristic for most countries situated in the East European region. It also identifies potential threats that may materialise in the absence of cooperation between countries and appropriate measures to jointly manage the shared water resources in the region.