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. Water quality can have a major impact on health, both through outbreaks of waterborne disease and by contributing to the background rates of disease. Accordingly, countries develop water quality standards to protect public health. Recognising this, the World Health Organization (WHO) has developed a series of normative “guidelines” that present an authoritative assessment of the health risks associated with exposure to health hazards through water and of the effectiveness of approaches to their control.