Residential neighborhoods produce wastewater originating from soapy water, oil, and similar wastes which are included in the gray water category, as well as rainwater runoff from tiles. The purpose of this study is to identify a Rain Garden model that is suitable for application in the residential areas of Makassar City. The method used is by identifying the suitability of the Rain Garden land, calculating the dimensions, and making the right Rain Garden model. From the results of the study it was concluded that the Rain Garden model for the reduction of gray water and rainwater runoff in the Makassar City residential environment was designed to have three cropping variations. With a flow rate of V = 0.3 m3 / s, the depth of flow Y = 1.2 m. Based on the relationship between the width and depth of flow at the best hydraulic section in rectangular shape, the channel bottom is B = 0.8 m, guard height (F) 30% Y = 0.36 m. The effectiveness of household waste treatment and rainwater runoff using this Rain Garden model, for BOD = 102.8 mg / L (inlet) to 8.4 mg / L (outlet). The highest TSS value was 79 mg / L (inlet) to 8.3 mg / L (outlet). The highest detergent value was 59.84 mg / L (inlet) and showed the yield after processing was 1.25 mg / L (outlet). Treatment of gray water and rainwater runoff in residential environments is to reduce the volume of liquid waste that enters the city drainage system and create a sustainable urban sanitation ecology.
