Sanitation 21  is an important component of the global sanitation toolkit, which presents a planning framework based on international best practices. Initially developed in 2006, this updated version builds on recent experiences where good planning has formed an integral part of achieving improvements in urban sanitation. The document sets out key principles and process guidelines to help city stakeholders develop appropriate and affordable solutions to sanitation problems, taking into account technology issues, management arrangements, institutional challenges and demands for improvement from different stakeholders.