The book gives theoretical knowledge and practical approaches on the complex process of water management in case of pollution with chemical and biological hazards. Frameworks addressing scientific and management strategies are included. Critical for successful prevention and control actions of accidental and intentional water pollution is the preliminary risk assessment, understanding of the hazards, and lessons learned from previous pollution events. Emphasis is given to biological hazards, which are as diverse as the list of chemical pollutants and represent groups belonging to algae, diatoms, bacteria, helminthes, parasites, and viruses. Chemicals and toxins are overviewed that may be used for intentional water pollution. Preventive and responsive driven strategies are addressed also to the agriculture as an important source for pesticide and fertilizer pollution. Societal characteristics and water ethics are considered as principal issues by developing assessment and management strategies for water pollution prevention and control.