The document discusses principles of sustainable sanitation. It defines sanitation as protecting and promoting human health and nutrition while protecting the environment. Sustainable sanitation systems are financially viable, socially acceptable, protect health and the environment. The document outlines a sanitation ladder and discusses criteria for sustainability, including health and hygiene, socio-cultural acceptance, financial and economic factors, environmental impacts, and technological appropriateness. Readers are instructed to apply these criteria to assess sanitation systems in their localities.