The "Water Resource Management and Education" work plan of the SANREM/Southeast Asia program was designed to facilitate the development of community-based water monitoring teams who could collect credible data on a regular basis and thus understand watershed trends. The community now has multi-year trend data on such things as bacteriological concentrations in rivers and drinking water supplies, stream discharge and sediment yield estimates. Thousands of samples collected by volunteers have provided a large amount of water information that would not otherwise be available because of limited assessments made by governmental or private agencies. The monitors are aware of what their information implies and they are influencing policy and community action in the Manupali River watershed and beyond. This paper will focus on the cost-effectiveness, reliability and value of community-based monitoring programs when they are implemented in technically sound and participatory ways.