Water supply and water management services are among the most critical infrastructures in society, providing safe and affordable drinking water, managing wastewater to avoid floods and environmental pollution, and enabling the reuse and replenishment of scarce water resources. With water and wastewater facilities and infrastructure intrinsic to our towns and cities, we must not underestimate the potentially catastrophic results of water supply contamination or disruption to the systems that regulate the water we rely on for essential agricultural, environmental, and municipal needs. This book presents 12 papers selected from those delivered at the NATO Advanced Research Workshop (ARW) on Physical and Cyber Safety in Critical Water Infrastructure, held in Oslo, Norway, from 8-11 October 2018. The conference brought together resource persons and decision makers from 12 NATO countries and 6 partner countries to share their experiences with the objective of formulating best practice based on recommendations and conclusions, to increase awareness of the risks that threaten current and future water utilities and services, to learn how to improve surveillance and preparedness, and to deal with a crisis should all else fail. Addressing the urgent need to focus on physical and cyber safety in one of the most critical infrastructures in our society, the book will be of interest to all those working in the field of water supply and waste water management.