This is the third edition of the WHOs guidelines which are used by countries worldwide to set standards for the regulation of drinking water quality and effective approaches to water safety management. This revised edition has been updated to take account of recent developments in risk assessment and management. Topics discussed include: a framework for drinking water safety and discussion of the roles and responsibilities of different stakeholders, such as national regulators, water suppliers and independent surveillance agencies; guidance on microbial safety of drinking water through safety plans; new scientific information on chemicals, waterborne pathogens and individual chemical hazards of actual or potential concern. It also considers the application of the guidelines in specific circumstances, such as in emergencies and disasters, and to specific applications, such as bottled water. It also contains information on over 130 documents which substantiate or explain the content of the Guidelines, and on good practice guidance in achieving drinking-water safety.