The effects of climate change on the RWH systems can be observed in terms of the percentage change in the water security for each system with respect to different AOGCM model downscaled results (Table 4). It is evident from the results that out of the six scenarios, the model output of GFCM21 accounts for the highest negative percentage change in water securities. This shows that the projected rainfall patterns under these model results will further deteriorate the water securities of the RWH systems. Except for the residential Type B scenario (Table 4), most of the other model outputs have resulted in either negative or neutral percentage water securities change. These negative changes are relatively small, except with the GFCM21 model results. For the residential Type B scenario, the projected model results show better water security level improvements (except for the GFCM21 model).