Aquifer storage and recovery investigations at well 6628-16623 drilled by MESA in The Paddocks wetland storm water treatment and holding site in the Salisbury Council area (Adelaide, South Australia) have been successfully completed. The work included high pressure injection followed by extraction of water with a salinity satisfying that of the intended use. This is the first high pressure injection site in South Australia which has been implemented in a deep, confined Tertiary aquifer of low permeability. Investigation of the upper part of the Tertiary aquifer sequence underlying the wetland indicates that the lower part of the first Tertiary aquifer (aquifer T1B), which has a salinity of 1,860 mg/L at this site, has the potential to store wetland treated storm water for subsequent reuse. Due to the low transmissivity (75 m2/day) of aquifer T1B, and high well losses, the experimental injection well was acidised, which improved the injection efficiency with mains water by 50%. Even so, the injection rate is limited to between 7 and 10 L/s, which results in an injection head of approximately 70 metres during week-long injection cycles. This behaviour appears to be repeatable indefinitely with no loss of well efficiency. In 1996 a total of 75 ML was injected, followed by a residence period of 97 days. Following this, the total injected volume was pumped out at a rate of 15 L/s continuously. The recovery efficiency of this first cycle indicates that 40% was recovered with a salinity similar to that of the injected water, 85% was recovered with a salinity less than 1,000 mg/L (the limit for drinking water), and 100% was recovered with a salinity less than 1,300 mg/L (good quality for irrigation). It is estimated that perhaps 120% of the injected volume would have to be pumped to raise the salinity level to that of the original groundwater. This indicates that in this hydrogeological environment the injected storm water has formed a bubble surrounding the well, which has since remained relatively stable. Further injection/recovery cycles are expected to result in even better recovery efficiency.