Since the globe managed to deliver the Sustainable Development Goals (SDGs) to the platform to replace the Millennium Development Goals (MDGs), Sustainability has become a global concern. Even though the world met the MDG target for drinking water, we have to sustain the water supply services, especially the rural water supply services to ensure a change in the livelihood of the rural poor. The main objective of this study is to formulate a DSS tool that can aid the rural water supply engineer and planner in decision-making regarding to the sustainability of rural water supply services. Three modules that comprise functionalities for data input, data analysis (data query), and display of results are employed in the computer program development using visual basic programming language by Microsoft Visual Studio Express. A user-friendly interface helps make the navigation of the software easy. The DSS tool identifies the sustainability status of a particular water supply service and further goes to identify the factors behind it from the most affecting factor to the least affecting factor in descending order.