The thesis concerns the design process of a control unit for rain harvesting systems. The design brief was given by Grundfos A/S. The main objective was to uncover the future user needs and interests in the year of 2015 as a base for a conceptual redesign of an existing control unit. This was done by researching households, mega trends and municipality politics to uncover the potential market in 2015. Potential users were interviewed and persona were created to be able to decide the future needs. Furthermore the future needs of the plumber was considered. The features of competitive control units were mapped, to be able to design a control unit that would stand out on the Danish market. The research resulted in a context-related solution that communicated the information requested by the users. The solution was a concept for the exterior of a control unit with a user-oriented display, a website for the household to keep track of statistics and an external software interface for the plumber to ease the setup of the unit. This solution is expected to fulfill the future user needs and interests in the year of 2015.