Indonesia is a country with wet tropical climate has constraints in obtaining thermal comfort because of the high air temperature, high air humidity and lower air speed. Modification of the microclimate might be conducted by increasing the cooling effect in a passive manner. Water can be used as one of control strategy thermal to build the microclimate or to site. Water also played an important role in lowering temperature and raise humidity in a room in building.Taman Sari Royal Heritage Spa, which is located in Yogyakarta,is one of building that implementing water as thermal control by making pool in door. This research aims to understand the influence of water in controlling the micro climate and the anything influence it .This research uses the quantitative methods by conducting observation and measuring temperature and humidity directly to the research objects. Secondary data is needed in this research. There was also literature review on the stuff that supports research, and a literature study was also conducted. The research and analysis on the results shows that 1 .The room in Tamansari royal heritage spa still in comfort zone in thermal .2 .The volume of water affects temperatures and humidity room 3 .Distance is a significant factor.