The fulfillment of STT-PLN water needs to be supplied from ground water. This will be decreased soil and soil water discharge due to large quantities of consumption. Areas of Indonesia have a high rainfall, i.e. 2, 000-4, 000 mm/year, should not have to worry about the availability of clean water. The problem faced is that there is no adequate management of rainwater. Based on these problems, it is necessary to develop methods of managing rainwater, harvesting and utilizing rainwater to meet the needs of clean water and water conservation for the sustainability of the carrying capacity of the environment. By calculating using 15 years daily rainfall data and roofing area as a catchment area to obtain the volume of potential water. The aim of this research is to analyze the amount of rainwater volume that can be accommodated in the rainwater harvesting system and to be processed as a clean water consumption.