The purpose of this work is to achieve an approximation on a sensitive social problem consisting in the progressive demand for water resources by a growing urban population and the possibilities that Aguas Santiago has to contribute efficiently to the rational supply of the precious Liquid under adverse natural conditions. To achieve the efficient management of the infrastructure to provide the service, it is necessary to determine the costs so that their knowledge contributes to the correct decision making to improve the efficiency of the processes that are carried out in the collection, purification and distribution of water, In order to achieve true public management. The article consists of exposing the contradictions that are generated in the Aqueduct and Sewer Company (EAAL) Aguas Santiago in the determination of the costs of the Aqueduct service.