As a suggestion to evaluate some of the attributable impacts to the environment policy implementation that establishes the programs for water saving and efficient usage, the construction of a simulating model from the utilization of a methodological dynamic systems focus was proposed. For the evaluation development, all the necessary information was put together for the characterization of the system that involves this efficiency and saving, starting from what is established in law 373/1997 and its statutory decree. This regulatory framework defines the work of drinking water and basic sanitation service providers in Colombia and offers the necessary tools for the formulation of efficient usage and water saving programs from which the environmental policy´s intentions materialize. On the other hand, conceptual and theoretical elements which define the different management focus from which the worldwide problematic level is approached were taken into consideration. The data that feeds the model used in the impact assessment comes from the information registered in the city of Pereira, depicting water supply and demand behavior in the urban area of this county. This information as well as the proposed strategies for water saving and efficient usage program implemented by the Empresa de Acueducto y Alcantarillado de la Ciudad de Pereira S.A E.S.P during the years 2003 thru 2007, brought up some of the impacts generated by the implementation of the environmental policy on the water resources and the consumption pattern behavior in the city of Pereira. The impact assessment from the dynamic systems allowed the establishment of alternative, strategies and important parameters to accomplish the set objectives in the environmental policy as well as the efficiency evaluation of some of the criteria established in it.