The most effective means of consistently ensuring the safety of a drinking water supply is through the use of a comprehensive risk assessment approach that encompasses all steps in water supply from catchment to consumer. The approach of this book is to promote an understanding of the entire water supply system, including the hazards that can compromise drinking water quality, safety and develops effective measures to assess and manage risks arising from those hazards using spatial model. Comparative evaluation of certain physical, chemical and biological characteristics of raw, treated and potable water at distribution network has been ongoing. Applying a GIS model will provide visual impacts for various hazards using WQI, which has formed a series of prediction maps for risk assessment. The objective of this book is to help researchers, professionals, and end-users working in water supply systems with the identification of relevant hazards by providing a catalogue with potential hazards of technical, environmental or human origin for the entire system.