19.9 Managed aquifer recharge
a. Recycled water system overview
The recycled water system is one of three sub-components of Perth's urban water system. The three sub-components are the:
- Urban water supply system
- Wastewater system
- Recycled water system.
In the Perth region, 8% of the treated wastewater from the wastewater system is recycled.
During the 2011–12 year, approximately 49% of the recycled water produced was resold for industrial use and local irrigation (part of 19.4). Approximately 24% of the recycled water was used on-site at the wastewater treatment plants throughout the region; the remaining 27% was used to recharge aquifers—via injection wells (19.9) or groundwater infiltration (19.10). The following figure shows all the inflows and outflows associated with the recycled water system.
For more detail on a particular flow associated with the wastewater system, refer to the line item notes. Note that volumes annotated with a * indicate flows between urban sub-components and are not reported in the account. As such, these flows do not have an associated line item number or note.
Schematic diagram of water inflows and outflows during the 2011–12 year for Perth's recycled water system. Line item numbers are provided in brackets.
b. Supporting information
This line item volume (1,212 ML) represents the total volume of treated wastewater transferred to groundwater via an injection well from the Beenyup Wastewater Treatment Plant during the 2011–12 year.
Treated wastewater from the Beenyup treatment plant is transferred to the groundwater store as part of the groundwater replenishment trial that commenced in November 2010. More information on the groundwater replenishment trial is provided on the Water Corporation website.
Treated wastewater from the Beenyup Wastewater Treatment Plant was transferred to the Advanced Water Recycling Plant where it underwent further treatment. The treated wastewater was then transferred into the groundwater store via an injection well. The volume of aquifer recharge is based on metered data at the recycling plant that is collected on an almost continuous basis.
Assumptions, limitations, caveats and approximations
Expected error for water meters is +/– 5%.
The Department of Water requires that all water meters, when tested under in situ conditions, must be within 5% accuracy across the full flow rate range (Guidelines for water meter installation 2009).