The quality of water, whether it is used for drinking, irrigation or recreational purposes, is significant for health in both developing and developed countries worldwide. In responding to this challenge, countries develop standards intended to protect public health. Recognising this, the World Health Organization (WHO) develops 'guidelines' that present an authoritative assessment of the health risks associated with hazards through water and of the effectiveness of approaches to their control. To date, the various WHO guidelines concerned with water (Guidelines for drinking-water quality; Guidelines for the safe use of wastewater and excreta in agriculture and aquaculture; Guidelines for safe recreational water environments) have been developed in isolation from one another. However, their common primary concern is for health hazards derived from excreta. Addressing their specific areas of concern together will tend to support better health protection and highlight the value of interventions closer to sources of pollution, which may otherwise be under-valued. The potential to increase consistency in approaches to assessment and management of water-related microbial hazards was discussed by an international group of experts between 1999 and 2001. These discussions led to the development of a harmonised framework, which was intended to inform the process of development of guidelines and standards. Subsequently, a series of reviews was developed and refined, which addressed the principle issues of concern linking water and health to the establishment and implementation of effective, affordable and efficient guidelines and standards. The book is based on these reviews and the harmonised framework. This book will prove invaluable to all those concerned with issues relating to microbial water quality and health, including environmental and public health scientists, water scientists, policy makers and those responsible for developing standards and regulations.