Jatiluhur Estate is an area located in Purwakarta Regency and was developed for residential, industrial, and commercial areas. Therefore, it is important to determine the availability of water that will meet water needs, and to evaluate the water reliability in future. This study aimed to model the river discharge in determination of water availability of Jatiluhur Estate. The methods used in this study include observational discharge data, evapotranspiration, rainfall, and area of flow. To analyze the availability of water, F.J. Mock method was used, where the F.J. Mock method can show water balance analysis for monthly discharge. The results showed that the availability of water with mainstay discharge Q80% and Q90% met the water needs of the Jatiluhur Estate or showed a surplus condition for 30 years (2020-2050).