The government provides clean water services that specifically manage, provide and distribute clean water for the community. Clean water providers in Banjarnegara Regency are managed by the Regional Public Drinking Water Company "Tirta Dharma". Some of the problems in the Subdistrict Capital of Bawang are related to reservoir capacity and inadequate discharge. This study aims to determine the clean water needs of PDAM Tirta Dharma customers in the Bawang District, as well as to review the availability of water sources in the reservoir. From the results of the study, it was found, First, the clean water needs of PDAM Tirta Dharma in Bawang District in 2030 amounted to 38 liters/second from all residents in Bawang District, while the clean water needs according to the predictions of each type of customer or house connection is 8 liters. /second, meanwhile the current available discharge is only 5 liters/second, so an additional discharge of 3 liters/second is needed. Second, the reservoir capacity required to meet the water needs of Bawang Subdistrict in 2030 is 40 m3, so there is no need for addition of reservoir capacity