T he population of Ambon City numbered in 2016 amounted to 427,934 people which increased from the previous year so that the demand for space increased. If the demand for space increases, the demand for drinking water needs also increases. At present, Ambon City PDAM only serves 10,233 customers from 66,094 households or only 15.47% of the lives served in Ambon City so that this study wants to predict water demand in 2029 with the achievement of a 100% target based on the Ambon City Spatial Plan. Data analysis techniques were carried out with two alternatives, based on the 100 liter / person / day. RTRW and alternative two with a minimum standard requirement of 60 liters / person / day with the calculation of domestic needs based on the population in the space and nondomestic pattern designation based on the unit. So that based on the results of analyzing the data, it is known that the total domestic and non-domestic needs in the two alternatives exceed the availability of water sources so that the target of achieving 100% by the RTRW is difficult to achieve. Thus to be able to achieve the 100% target of service, it is necessary to conduct research on the potential of raw water in Ambon City so that it can be managed to provide better and more sustainable drinking water needs by 2029.