Rainwater harvesting systems (RHSs) can be used to improve the efficiency of helicopter fire-fighting operations. To this end, RHSs need to be strategically located in areas with high wildfire occurrence to maximize their usefulness. In this study, spatial analysis was carried out to determine suitable sites for establishing RHSs intended for air attack operations in three municipalities (Chalco, Ixtapaluca and Tlalmanalco) located in the eastern part of the state of Mexico, Mexico. Five variables were used for site selection: wind speed, distance to roads, runoff, evaporation and wildfire density. Each variable was graded by consulting experts and multi-criteria decision analysis was performed to integrate them on a map. Potential RHS sites that met most of the criteria established are in the north and south of the study area. The method used in this study to identify suitable sites for establishing RHSs is a useful tool. Expert knowledge and field visits would also be helpful in selecting the best RHS site and design, in order to reduce costs and environmental impacts.