Tanzania has created, since the mid-90s, an original institutional framework for water and sanitation management made of a mix of decentralized initiative and public control. This article presents this framework and its functioning on sanitation issues in the town of Moshi, a medium-sized town located on the south slopes of the Kilimanjaro Mountain. Findings are coming from a pluridisciplinary franco-tanzanian research program dedicated to these issues in 2002 and 2003. The objective of this work was to identify - through a regulation analysis of the sector and an analysis of households' needs and demand - the stakeholders of the sector and to study their behaviours and their interactions. Using the output of this program first trends of policies were elaborated during a workshop held in November 2003 with all the main stakeholders who could exchange their different perceptions of the problems and their ideas to solve them.