This book reviews groundwater quality and its major global contaminants, and collects the latest advances in the analysis, remediation, risk assessment, and hydrogeochemistry of groundwater in countries such as Algeria, Egypt, Ghana, Kazakhstan, Morocco, Saudi Arabia, and the USA. This book mainly focuses on the major arid and semi-arid areas where groundwater is scarce and highly polluted with geogenic and anthropogenic contaminants and the recharge to the groundwater is negligible due to limited rainfall. Divided into 2 parts, the book starts by covering topics like assessment and protection of groundwater in arid and semi-arid regions, groundwater pollution, and contamination risk assessment. Particular attention is given to the application of environmental isotopes in groundwater studies and how anthropogenic activities impact groundwater quality, the impact of irrigation reservoirs in groundwater and soil quality, and how artificial intelligence is applied to forecast groundwater quality. In the second part of this book, readers will find more about the major global contaminants of groundwater in arid and semi-arid areas, including a geochemical analysis of fluoride and nitrate contamination. Supported by regional case studies, this book appeals to researchers, scholars, and professionals working in the field of groundwater contamination and remediation and is also an important account for policymakers.