External Q+A's on the Guidelines for Drinking-water Quality, 4th Edition
Why are these Guidelines important?
Water is essential for life, but it can and does transmit disease in countries in all continents—from the poorest to the wealthiest. The most predominant waterborne disease, diarrhoea, causes two million deaths every year. Drinking-water quality management has been a key pillar of primary prevention for over one-and-a-half centuries and it continues to be the foundation for the prevention and control of waterborne diseases. The Guidelines are a flagship normative publication of WHO.
How can the recommendations make a difference?
The Guidelines recommend shifting the focus from reacting to contamination events to preventing their occurrence. Country policies frequently overemphasize end-product testing as a means to ensure the safety drinking-water. Unfortunately, adverse test results are not known until the water has already been consumed and people have already gotten sick. This Edition provides guidance on how to formulate regulations and promote good practice to assess and reduce risks of contamination before it is too late. If the recommendations articulated in these Guidelines were to be effectively implemented, waterborne outbreaks and disease could be substantially reduced.
What type of guidance is presented?
The Guidelines provide an evidence-based point of departure for standard setting and regulation as a basis for health protection. They include an assessment of the health risks presented by the various microbial, chemical, radiological and physical constituents that may be present in drinking-water. While the guidance is advisory in nature, health-based guideline values for hazardous constituents are derived and presented as maximum recommended concentrations.
What are the core recommendations of the Guidelines?
The Guidelines promote a framework for safe drinking-water, composed of health-based targets, water safety plans, and independent surveillance. Health-based targets are measurable health, water quality or performance objectives that are established based on a judgement of safety and on risk assessments of waterborne hazards. Water safety plans (WSPs) provide the instrument make the Guidelines operational. WSPs require systematic catchment-to-consumer risk assessment and management and emphasize prevention for long-term improvements in water quality. Drinking-water supply surveillance entails the continuous and vigilant public health assessment and review of the safety and acceptability of drinking-water supplies.
How is this different from previous versions?
This Edition has been systematically revised in a process involving hundreds of experts, numerous consultations, and a period of more than five years. It builds on previous editions, expanding and further clarifying key concepts like health-based targets and water safety planning. Substantial new text has been introduced on how to implement these Guidelines, including on adapting these to national/local circumstances, for example through the establishment of interim standards to encourage step-wise improvements in resource-limited contexts.
It has new guidance on emerging issues of public concern like pharmaceuticals in drinking-water and the chapter on radiological aspects has been comprehensively revised. New or improved explanations have been incorporated on how to more effectively manage drinking-water quality in a range of specific circumstances including: climate change risks, emergencies, bulk water supplies, household-level water management including rainwater harvesting and point-of-use treatment and safe storage.
New or revised risk assessments have been applied to over thirty chemical and microbial hazards, including emerging organisms of concern. New guidance has been formulated on applying pesticides to drinking-water for public health purposes (e.g. to control mosquito larvae in potable water containers in order to prevent dengue transmission).
WHO's role in drinking-water safety: guidelines, not standards?
One of the main roles of WHO is to establish international norms to protect human health. Since 1958, as part of its activities on drinking-water and health, the Organization has published several editions of International Standards for Drinking-water and subsequently, the Guidelines for Drinking-water Quality.
In 1982, WHO shifted its focus from ‘International Standards’ to ‘Guidelines’. The main reason for the shift is the advantage provided by the use of a risk-benefit approach (quantitative or qualitative) to the establishment of national standards and regulations. Specifically, the application of the Guidelines to different countries should take account of the sociocultural, environmental and economic circumstances particular to those countries.
WHO Member States have recognized the urgent need to improve drinking-water safety, and called upon WHO to strengthen its technical advice in this area in a World Health Assembly Resolution, agreed to in May 2011.
Who uses the Guidelines?
The Guidelines are addressed to water and health regulators, policy-makers, and their advisors, mainly to assist them in the development of national standards. The Guidelines are also used by many others such as water suppliers and practitioners as an international scientific point of reference on water quality and health, and effective water safety and management approaches.
The Guidelines for Drinking-water Quality are recognized as the UN system’s official position on drinking-water quality. The European Commission and Japan use the Guidelines as the scientific point of departure for their drinking-water directive and drinking-water quality standards, respectively; the Australian Drinking Water Guidelines are based on the WHO Guidelines, while the United States Environmental Protection Agency (USEPA) and Canada's Health Canada actively observe and participate in the WHO Guidelines development and updating process.
Many developing countries use the Guidelines directly or indirectly in setting national standards. The Guidelines are often used where guidelines or standards are unavailable and are also referred to in the food standards developed by the Codex Alimentarius Commission (for instance, for mineral water and bottled water).
Water suppliers—both larger utilities and those providing water to small communities—will find the recommended management approaches to be practical and effective ways to assure drinking water quality.