In recent years, sustainable thinking has been gradually recognized and accepted by more and more users, enterprises, and stakeholders. However, in daily life, there is often a gap between the value of users’ pursuit of sustainable lifestyles and their behavior habits. Also, the connection between different stakeholders is often ignored. The project started by the observation of unsustainable water usage habits of some tenants in the Växjö local housing company Växjöbostäder, and investigated the gaps in the water supply/toll system of Växjö municipality for some apartment tenants and the limitations of current solutions. Therefore, it is necessary to find a more effective solution. The author attempts to guide and change the user’s behavior through design interventions led by digital user experience design, connect the gap between the user and the system, and provide a more sustainable choice. At the same time, as a precedent, this project’s attempt to apply sustainable behavioral interventions to the field of digital user experience products at the system level can also provide some reference for similar projects or designs that may appear in the future. The aim of this project is trying to find solutions to bridge the existing gap between the water management system and the apartment users’ water consumption behavior. The project studies the relevant theories of behavior, analyzes the causes of motivations that lead to behavioral and habits changing, the methods of digital user experience design, and the theory of building sustainable systems. Action research has been used as a methodological guide to design processes, analysis, and reflection. The final design outcome “Drops” is an application based on mobile platforms that develop sustainable water-using habits. The application associates gamification motivation mechanisms, behavioral habit interventions, community social sharing, and the process of using the application with the user’s actual behavior, promotes the formation of user sustainable behavior and inspires users to a sustainable society thinking. From a hierarchical analysis of the system, “Drops” connects different stakeholders in the municipal water supply system, facilitating communications between tenants and communities to achieve positive interactions that promote sustainable behavior.  At the end of this article, the author analyzed the project outcome from the perspective of Växjöbostäder, one of the stakeholders and a possible product distributor, elaborated on the possible advantages of the design for the company’s ecological sustainability and the possibility of the company deploying this application in the market. Also, the author also analyzed and evaluated this project from the perspective of the product itself and different stakeholders, and explained the current limitations and the possibility of future development.