Water and Sanitation programmes normally involve big amounts of information and several years of implementation; these are facts that justify the need of a proper monitoring. In this paper a Support Information System (SIS) for WatSan programmes monitoring is presented. SIS is based on a database system where relevant data of the programme can be easily stored and processed through user-friendly interfaces. Graphical representation has been included, facilitating the analysis and allowing for a better response on real time while programme is being implemented. The Logical Framework has been used as the starting point to define the tool. Experience has shown that it is crucial to create it with a participatory approach together with professionals working directly on the project. After its application in two programmes in Tanzania it has been seen that the tool allows both for a day-to-day monitoring as well as for a long-term analysis, improving knowledge of the staff working on project implementation, researchers and development planners.