This paper investigates the impact of the dissemination of modern irrigation systems, i.e. private wells with pumps, on the livelihood not only among the farmers who have access to wells but also among the farmers who have no access to wells and thus rely solely on traditional irrigation systems called tank irrigation systems. The analysis is based on a village and household data set collected in Tamil Nadu, India where tank irrigation systems have been managed collectively for rice cultivation. Our statistical analyses predict that once declines in collective management occur due to the dissemination of private wells, the rice yield and income of the no-well-access farmers alone will decrease, resulting in increased poverty among them. Our analyses also find that the dissemination leads to the overexploitation of groundwater, and thus results in no significant increase in rice profit among the well-access farmers. In this way, the dissemination of private wells creates double tragedies: not only increased poverty among the no-well-access farmers but also overexploitation and profit reduction among the well-access farmers.