19.5 Discharge from urban water system to surface water
a. Discharge from urban water system to surface water
The volume reported (2,203 ML) represents discharge from several wastewater treatment plants (WWTPs) operated by SA Water into rivers in the Adelaide region. The breakdown of WWTP discharge is presented in the following table. Treated wastewater from the Victor Harbor WWTP is temporarily stored in Hindmarsh Reservoir during summer and then released to the Inman River in the winter months.
|Wastewater treatment plant||
Surface water discharge point
Discharge volume (ML)
|Angaston||North Para River||
|Bird-in-Hand||Dawesely Creek–Onkaparinga Catchment||
|Hahndorf||Hahndorf Creek–Onkaparinga Catchment||
|Victor Harbor||Hindmarsh Reservoir and Inman River||
b. Wastewater system overview
The wastewater system is one of three sub-components of Adelaide's urban water system. The three sub-components are the:
- urban water supply system
- wastewater system
- recycled water system.
In the Adelaide region, wastewater is collected (line item 11.4) from users and treated by SA Water at one of their wastewater treatment plants.
During the 2011–12 year the majority (70%: line item 19.7) of treated wastewater was discharged to sea; approximately 25% was recycled (see recycled water system overview) and the remaining portion was discharged to surface water (2%: line item 19.5) or lost during wastewater treatment processes (3%: part of line item 19.20).
The following figure shows all the inflows and outflows associated with the wastewater system. For more detail on a particular flow associated with the wastewater system, refer to the line item notes. A small misbalance is shown and can be attributed to metering inaccuracies and unaccounted losses.
Note that volumes annotated with a * indicate flows between sub-components and are not reported in the account. As such, these flows do not have an associated line item number.
Schematic diagram of water inflows and outflows for Adelaide's wastewater system during the 2011–12 year; line item numbers are provided in brackets
The metered discharge of wastewater to surface water during the 2011–12 year from these WWTPs was supplied from WWTP records held by SA Water. These metered flows were manually read and recorded by plant operators.
Assumptions, limitations, caveats and approximations
Treated effluent from the Victor Harbor WWTP was discharged to Hindmarsh Reservoir for summer storage and then released to the Inman River in winter months.
The line item does not include any discharge from community waste management systems that were managed by local councils.
The uncertainty estimate is not quantified.
This line item corresponds to line item 19.5 'Urban water discharge to surface water' reported in the 2011 Account.