The Karnali river basin has been experiencing rainfall variability and incidents of more frequent drought in recent years. Geographical constraints and people’s relatively low economic capacity and the climatic variability are affecting the water availability to people living therein. Smallscale water infrastructures such as village ponds and tanks play a crucial role in domestic water-supply and in agriculture where canal irrigation is limited. However, lack of proper knowledge on the installation of rainwater harvesting systems is one of the major hindrances in promoting rainwater harvesting in this region. To address the water scarce condition with the use of ICT, an android based mobile application Aakashepani has been developed using the available physical and socioeconomic information and the cutting-edge technology. Aakaashepani (आकाशेपानी) is an Android-based, userfriendly and interactive mobile application, used for calculating optimal household tank size, and obtaining other technical and financial aspects of rainwater harvesting systems. This application incorporates information from local precipitation patterns, and types and dimensions of roofs and their runoff coefficients, including households’ water requirements. The user needs to provide the water consumption activities such as demography, livestock etc. Using the information, monthly water requirement and availability is assessed to generate the optimal tank size for each household at a specific location. The application also provides the user with an estimated cost, and a list of nearby vendors where people can purchase the parts of the rainwater harvesting system. This application is freely available and highly customized to the local context of the Karnali basin, providing excellent opportunity to build up the adaptive capacity of the local people. This application was released recently and is freely available in Google Play Store. The grant will provide hands-on training on the app installation, tank size calculation and the science behind the application.