An irrigation tank is a small reservoir constructed across the slope of a valley to catch and store water during the rainy season so it can be used for irrigation during the dry season. The survival of tank irrigation systems in India is challenged by growing scarcity and competition among multiple users over water resources. This paper examines the social interaction processes among the multiple users of tank irrigation systems and draws implications for sustainable management of the tanks. A random sample of 31 tanks in tank intensive district of Tamil Nadu state which had maximum number of uses were selected for the study.. About 15 key informants were purposively identified from each of these tanks for data collection through participatory rural appraisal. The results reveal that, head and tail end farmers of the tank command competed for irrigation water. Competing users include encroachers, fish and duck farmers. Conflicts in sharing water occurred mostly between adjacent farmers due to overuse of water as against their allotted share. Existence of weak property rights in tanks remained as the reason for the competition and conflicts. Conflicts aroused during water scarcity conditions and were mostly settled by the community leaders and water users association (WUA). Damaged of the tank structures, encroachers of tank and presence of conflicting interests among the multiple users remained as the major causes for the conflicts. WUA must play major role in promoting the collective actions among user groups to use the tank resources sustainably. Strategic actions for sustainable management and conservation of the water resource are highlighted.