Chemical safety of drinking-water : assessing priorities for risk management

As a supporting document to the WHO Guidelines for Drinking-water Quality, this publication intends to help users at national or local level to establish which chemicals in a particular setting should be given priority in developing strategies for risk management and monitoring of chemicals in drinking-water. It is written for public health authorities, those responsible for setting standards and for surveillance of drinking water quality, and water supply agencies responsible for water quality management. It is useful in settings where information on actual drinking-water quality is limited, which is the case in many developing countries and in rural areas of some developed countries. Once priority chemicals have been identified, subsequent risk management strategies may include setting standards, monitoring and control.

It is divided into three parts:
Part A provides general guidance on using limited information in prioritizing chemicals in drinking-water for risk management.
Part B provides practical guidance on the identification of specific chemicals that are likely to be of concern in individual water supply systems. It groups chemical contaminants into five categories on the basis of their potential sources: naturally occurring, from agriculture activities, from human settlements, from industrial activities, and from water treatment and distribution processes themselves.
Part C comprises the appendices. It includes guidance on the most likely sources of potential contaminants and on identifying chemicals that could be of concern in particular circumstances. This information is presented in an accessible format that will help users to determine the chemical hazards that can arise in the catchment, in treatment and in distribution, in large, medium and small water supplies.