A shit flow diagram, also known as an SFD or excreta flow diagram, is a tool used to visually depict the management of human waste within urban sanitation systems. It distinguishes between safely and unsafely managed human excreta through color-coded arrows, providing insights into areas needing sanitation improvements. Initially developed through international collaboration, SFDs are commonly employed in urban sanitation planning and policy formulation, especially in low- and middle-income countries. Their creation involves data collection, stakeholder engagement, and systematic analysis. While SFDs offer valuable visual representations, their accuracy can be limited by data reliability issues and technical constraints, which ongoing methodological developments aim to address.