Debates on the total or partial privatization of water usually follow the rationale that efficient and rational management is best left to the private sphere. In this paper and using a historical example, we attempt to assess critically this assumption arguing that efficiency and rationality in resource management are and have been an asset of collective management as well. We present the case of the Barcelona Water Company, run by its workers during the Spanish Civil War, to illustrate how in certain cases, gains in economic efficiency and rational management that had been impossible to accomplish under standard private management, were achieved by collective action. Workers management during this period not only improved efficiency and rationality but to a large extent did so also procuring equity and fairness in the provision of water to the citizens of Barcelona despite the harsh conditions brought about by the war.