Rainwater harvesting (RWH) system is a technology that focuses on sustainability and support the sustainable environment development. The implementation of RWH systems provides many environment and financial benefits. Some of the environment benefits of RWH system are the reduction of surface runoff, reduce the burden of soil aquifer, and provide the availability of clean water. This study analyzed the RWH system implementation benefits both in environment and financial side. The financial benefits of RWH system implementation are calculated based on a number of rainwater that can be used to replace the need for clean water.The environment benefits defined by the reduced of main water tap use and the reduced of generated roof runoff volume. This study used a simple RWH system that use the roof as a catchment area, the pipeline as a distribution system, and tank as the storage system. The water use is for domestic potable and no potable for a household with up to four occupants in Bandung. The catchment area is taken 70 m2. A water balance model for various scenarios was developed to calculate the algorithm of the system. The costs taken in RWH system includes the construction, installation, maintenance and operational costs. The analysis shows that the implementation of RWH systems provides advantages over the use of conventional systems. It can save clean water use up to 54,92% and provide runoff reduction up to 71,53%. RWH system applied requires additional costs approximately only 0,66% from the value of the house. It was found that it is possible to achieve payback in RWH system implementation under several scenarios.