Sanitation is as a multi-step process in which human excreta and wastewater are managed from the point of generation to the point of use or ultimate disposal. A Sanitation System is a context-specific series of technologies and services for the management of these wastes (or resources), i.e., for their collection, containment, transport, transformation, utilisation or disposal. A sanitation system is comprised of Products (i.e. waste, organic wastewater, excreta, blackwater, greywater, etc.) that travel through functional groups, which contain Technologies that can be selected according to the context. By selecting a Technology for each Product from each applicable Functional Group, one can design a logical Sanitation System. A sanitation system also includes the management, operation and maintenance (O&M) required to ensure that the system functions safely and sustainably.