Guidelines for drinking-water quality: fourth edition incorporating the first, second and third addenda

Overview

The fourth edition incorporating the first, second, and third addenda of the World Health Organization’s (WHO) Guidelines for drinking-water quality (GDWQ) builds on over 65 years of WHO guidance on drinking-water quality. This guidance has formed an authoritative basis for the setting of national regulations and standards for water safety in support of public health.

The Guidelines provide a comprehensive framework for protecting public health through the management of drinking-water quality risks, from catchment to consumer. They support the development of health-based targets, risk-based management approaches and independent surveillance.

This latest version incorporates updates that reflect new evidence and substantive implementation experience to better support the effective application of the Guidelines in a range of settings.

What is new?

Key updates in this version include:

• clearer recognition that small water supplies need explicit consideration in policies and regulations, along with appropriate support for implementation;
• strengthened emphasis on the role of governments in supporting risk management by water suppliers, including through water safety plans and sanitary inspections;
• updated guidance on water safety plans and sanitary inspections, drawing on additional experience in development and implementation;
• new or updated matrices to support prioritization of action and progressive improvement based on results from both microbial water quality tests and assessment of water suppliers’ risk management practices;
• updated information on microbial pathogens, including revised pathogen-specific fact sheets and summary tables;
• updated information on pesticides used for vector control in drinking-water, reflecting WHO’s latest guidance; and
• additional references to WHO resources to support implementation, including guidance on small water supplies, sanitary inspections, lead in drinking-water and cyanobacteria management.

More details on the updates are included in the GDWQ preface. A companion summary note provides further detail on the main changes.

Introduction
A conceptual framework for implementing the Guidelines
Health-based targets
Water safety plans
Surveillance
Application of the Guidelines in specific circumstances
Microbial aspects
Chemical aspects
Radiological aspects
Acceptability aspects: taste, odour and appearance
Microbial fact sheets
Chemical fact sheets
Annex 1: Supporting documentation to the Guidelines
Annex 2: References cited
Annex 3: Chemical summary tables
Annex 4: Analytical methods and achievability
Annex 5: Treatment methods and performance
Annex 6: Supporting information on radionuclides
Annex 7: Contributors to the development of the Guidelines for drinking-water quality: fourth edition incorporating the first, second and third addenda