Over the past decade, we have witnessed a growing scarcity of and competition for water around the world. As the demand for water for domestic, municipal, industrial, and environmental purposes rises in the future, less water will be available for agriculture. But the potentials for new water resource development projects and expanding irrigated area are limited. We must therefore find ways to in-crease the productivity of water used for irrigation. This paper reviews the literature on irrigation efficiency and on the potential for increasing the productivity of water in rice-based systems. It identifies the reasons for the wide gap between water requirement and actual water input in irrigated rice production systems and discusses opportunities for bridging the gap both on-farm and at the system level. The potentials for water savings in rice production appear to be very large. But we do not know the degree to which various farm and system interventions will lead to sustainable water savings in the water basin until we can quantify the downstream impact of the interventions. Studies on the economic benefits and costs of alternative interventions are also lacking. Without this additional information, it will be difficult to identify the potential benefits and the most appropriate strategies for increasing irrigation water productivity in rice-based systems. This paper emphasizes the need for integrating various water-saving measures into practical models and for conducting holistic assessments of their impact within and outside irrigation systems in the water basin.