Generation of Virtual WDS to Complete Cadastral Information of Existing Systems Juliana Robles 1 , Juan Saldarriaga 2 1 Research Assistant, Water Supply and Sewer Systems Research Center CIACUA, Universidad de los Andes, Bogota; e-mail: j.robles1812@uniandes.edu.co 2 Professor, Department of Civil and Environmental Engineering, Universidad de los Andes, Bogota; e-mail: j-saldarr@uniandes.edu.co Abstract Information related to Water Distribution Systems (WDS) in small and intermediate cities often may be incomplete or unreliable, and data acquisition may be infeasible due to elevated time and economic costs. This lack of information can lead to inaccurate network operation and maintenance, and it can also limit the use of calibrated hydraulic models to support future designs in the system. Virtual case studies can thus be treated and used to overcome the insufficient data problems. The results are not case-specific as the obtained with benchmark networks. This paper aims to evaluate a new methodology by generating virtual networks for different cities in Colombia and then comparing resulting virtual WDS with the real systems, based on data obtained from water utilities. For both sets, network layout similarity and hydraulic factors were analysed. The results of the comparison between real and virtual networks make it possible to conclude about the applicability and limitation of this virtual generation software in small cities or DMAs in large cities, and also allows suggesting alternative solutions. INTRODUCTION Water Distribution Systems (WDS) are an important part of public networks in cities, as they allow the population of a service area to receive water in optimal conditions, regarding pressure and quality. Therefore, a proper performance that guarantees the accomplishment of the service levels requires an ongoing maintenance based on a detailed knowledge of the system components. This information is vital in WDS modelling when it comes to monitoring the system and plan expansions, among others. However, disorganized and rapid population growth may complicate data acquisition and adversely affect the quality of it. For water utilities, this process is costly in terms of time and money, and may achieve incomplete models only and, as a result, regular system analysis. Research strategies include study cases to create, prove and amend theories. Benchmark networks as New York Tunnels, Two Loops, Anytown and Hanoi were developed to compare results obtained in different studies. Though these networks were extensively used with test aims, the results are case-specific and should not be applied to different scenarios (Sitzenfrei, 2012). Due to safety reasons and poor data sets, investigations can also rely on virtual or semi- virtual networks. These models tackle the lack of information and mimic real data sets development that can be used as case studies or preliminary designs for new systems. One common example of virtual networks are Micropolis and Mesopolis presented by Brumbelow, Torres, Guikema, Bristow, and Kanta (2007). This WDS include developmental timeline spanning and critical infrastructure dependencies in addition to geography, demography and