Perth has a dry climate with most rainfall confined to winter season. By recharging treated wastewater into suitable aquifers along the coastal margin of Perth, a range of benefits may be achieved including: (1) prevention of saline water intrusion; (2) restoration of groundwater levels; (3) water banking and withdrawal to balance seasonal differences in water supply; (4) improvements in water quality; and (5) flexibility in aquifer management. The technical key points to implement this wastewater reuse strategy are in the hydrogeological sustainability, groundwater contamination, and treated wastewater quality. Recent developments in wastewater treatment technology have made it possible to convert sewage into fair quality/potable water. With the available data on Perth groundwater, a cost-effective wastewater treatment process is designed, which is intended to fully utilize the geopurification function. Numerical analysis is performed to investigate the impact of the reclaimed water injection on Perth basin's hydrogeology and chemical, biological content in subsurface formations. Deep aquifer injection and shallow aquifer injection are both considered.