Environmental pollution and future scenarios associated with increasing population foresees the water shortage even water scarcity in parallel to climatic conditions. In large cities, municipalities have to plan and expand their infrastructure investments based on the projects related with water consumption values which are estimated according to population growth using prediction methods. Thus water consumption is vital in large metropolitan city planning. In this study, water consumption of the 39 districts of Istanbul was investigated during the period of 2010-2014. However, in 18 districts of Istanbul, there is no statistically significant established pattern. Main reasons of failures of modelling are considered as migration, restructuring of the administrative borders, and re-planning of the districts as either industrial or commercial districts.