This communication is presenting a specific association of Role Playing Game and Agent Based Modelling aiming at increasing the empowerment of final users in the collective decision processes for water management issues. Role Playing Games and simulations on a generic basin are a way to bring distance with private interests in dialogue processes. We describe here a tool, PIEPLUE, designed as a hybrid of a Role Playing Game and a Computer Based Agent Based Model. This tool represents virtual farmers in a virtual river basin using water to irrigate various crops. These farmers choose individual organizational patterns concerning crops choice and water use choices. At the end of simulated cropping season, players may adapt the collective rules for sharing water. This communication is presenting the results of a first test with the river basin institution of the Drome River Valley in the South of France.