This manual suggests design operating and performance criteria for specific surface water quality conditions to provide the optimum protection from microbiological contaminants.

Issued to highlight information appropriate to small systems, to provide a background on regulations, and to present a summary of related research with an emphasis on filtration and disinfection technologies. Also includes information on how the systems can be "packaged" with remote monitoring and control technologies to provide a healthy and affordable solution for the small systems.

Small drinking-water supplies commonly experience operational, managerial, technical and resourcing challenges that impact their ability to deliver safe and reliable services. The needs and opportunities associated with these supplies therefore warrant explicit consideration in policies and regulations. These Guidelines, specifically tailored to small water supplies, build on over 60 years of guidance by the World Health Organization (WHO) on drinking-water quality and safety. They focus on establishing drinking-water quality regulations and standards that are health based and context appropriate; on proactively managing risks through water safety planning and sanitary inspections; and on carrying out independent surveillance. The guidance is intended primarily for decision-makers at national and subnational levels with responsibility for developing regulatory frameworks and support programmes related to these activities. Other stakeholders involved in water service provision will also benefit from the guidance in this document. Designed to be practical and accessible, these Guidelines offer clear guidance that is rooted in the principle of progressive improvement. State-of-the-art recommendations and implementation guidance are provided, drawn from a comprehensive evidence review and established good practices. Additionally, case examples are provided from countries and areas around the world to demonstrate how the guidance in this publication has been implemented in practice in a wide variety of contexts. Together with WHO’s 2024 Sanitary inspection packages – a supporting tool for the Guidelines for drinking-water quality: small water supplies, these Guidelines update and supersede WHO’s 1997 Guidelines for drinking-water quality. Volume 3: surveillance and control of community supplies. Key changes to this updated publication include a greater focus on preventive risk management and a broader range of small water supplies covered, including those managed by households, communities and professional entities.