Rainwater collecting is one option that may enhance drinking water availability directly at home, given that water security is expected to deteriorate as a result of climate change. Although rainwater collecting systems have the potential to decrease drinking water insecurity, they have never been rigorously evaluated in a range of regions for various climate change scenarios using consistent assumptions. As a result, the purpose of this paper is to evaluate the ability of rainwater harvesting devices to improve domestic water security in each of the major climate zones under various climate change scenarios, as well as to make design recommendations for each climatological region to achieve high levels of reliability. The linked model includes a stochastic weather generator (LARS-WG) that uses historic weather data from 94 locations selected to represent all Koppen – Griegel climatic categorization zones to generate synthetic daily rainfall. Three distinct climate change scenarios are simulated using 15 downscaled General Circulation Models up to the year 2099. Rainwater harvesting system dependability is evaluated using a variety of roof area and tank sizes. Climate change will have minimal effect on rainwater collecting, according to the findings, and rainwater harvesting may decrease household water insecurity even in dry areas. Implementing agencies may utilize the findings of this research to assist communities build systems that satisfy certain levels of dependability and to select areas where rainwater collecting can be successful.