Because of the increasing worry about water shortage, water management is an essential problem in urban planning. As a consequence, rainwater collecting systems have gotten a lot of interest as a source of alternative water. Rainwater is one of the cleanest forms of water, and a rainwater collecting system can readily obtain it. In general, the performance of a rainwater collecting system is evaluated using historical rainfall data, ignoring any potential climate change effects on rainfall. However, as a result of climate change, rainfall patterns are expected to alter in the future, affecting the effectiveness of a rainwater collecting system. However, there is a scarcity of study on the effects of climate change on rainwater collecting. Based on predicted future rainfall circumstances, the goal of this research is to evaluate the probable effects of climate change on the performance (i.e. water savings, dependability, and water security) of a home rainwater collecting system. To simulate the operation of a rainwater harvesting system, a continuous daily simulation water balance model is created based on behavioral analysis and yield-after-spillage criteria. The research is carried out at five sites throughout Australia's Greater Sydney area. The findings suggest that future climate change circumstances will have a detrimental effect on the functioning of a rainwater collecting system. It was discovered that, in the future, a given tank capacity at the chosen sites will not be able to provide the anticipated amount of water due to changing climatic conditions