Malaysia is well endowed with abundance of natural water resources, which has significantly contributed to the socio-economic development of the country. However, the situation has somewhat changed over the last decade. The water demand was 174.22 M/l/d in year 2010 and it is projected to be 270.77 M/l/d in 2050. In such scenario, a reliable and safe supply of water for future generations, more and more reservoirs will be required. The aim of this study is to apply GIS in identifying the most suitable location for water reservoir for area of Batu Pahat, Johor, West Malaysia. Methodology is designed in such a way to achieve the objectives of this study as to identify the important criteria for locating water reservoir, to model the location of reservoir using Analytical Hierarchy Process (AHP) and to analyze and evaluate the most potential sites for water reservoir using ArcGIS 10.1 software. Based on the criteria chosen, the data are processed and analyzed the existing 52 reservoir locations and their capacities. Based on the projected number of population for the year 2050, as a result, 5 new reservoir locations have been identified to fulfill the future demands of water for the study area. Thus, it can be concluded that the weights derived from AHP integrated in ArcGIS can be a useful tool in GIS analysis for the determination of suitable locations for water reservoir in the study area.