In 2004, the WHO Guidelines for Drinking Water Quality recommended that water suppliers develop and implement "Water Safety Plans" (WSPs) in order to systematically assess and manage risks. Since this time, governments and regulators, water suppliers and practitioners have increasingly embraced this approach, but they have also requested further guidance. This much-anticipated workbook answers this call by describing how to develop and implement a WSP in clear and practical terms. Stepwise advice is provided through 11 learning modules, each representing a key step in the WSP development and implementation process: 1. Assemble the WSP team; 2. Describe the water supply system; 3. Identify hazards and hazardous events and assess the risks; 4. Determine and validate control measures, reassess and prioritise the risks; 5. Develop, implement and maintain an improvement/upgrade plan; 6. Define monitoring of the control measures; 7. Verify the effectiveness of the WSP; 8. Prepare management procedures; 9. Develop supporting programmes; 10. Plan and carry out periodic review of the WSP; 11. Revise the WSP following an incident ; Every Module is divided into three sections: 'Overview', 'Examples and Tools', and 'Case studies'. The overview section provides a brief introduction to the Module, including why it is important and how it fits into the overall WSP development and implementation process. It outlines key activities that should be carried out, lists typical challenges that may be encountered, and summarizes the essential outputs to be produced. The examples and tools section provides resources which could be adapted to support the development and implementation of WSPs. These resources include example tables and checklists, template forms, diagrams, or practical tips to help a WSP team address specific challenges. These are often example outputs and methodologies adapted from recent WSP experiences. Each Module concludes with case studies so the reader can benefit from lessons-learned from real-life experiences. They are intended to make WSP concepts more concrete and to help readers anticipate issues and challenges that may arise. The descriptions were drawn from WSP initiatives in Australia, the Latin American and the Caribbean region (LAC), and the United Kingdom.