Adelaide
19.5 Discharge from urban water system to surface water

The volume reported (4,620 ML) represents treated wastewater discharge from five wastewater treatment plants (WWTPs) to rivers in the Adelaide region and potable water discharge from  Swan Reach–Stockwell Pipeline to the South Para River. The following table details the volumes of  treated wastewater and potable water discharged to rivers during the 2012–13 year. 

Discharge to surface water in the Adelaide region during the 2012–13 year

Discharge type	Discharge description	Volume (ML)
treated wastewater discharge	Angaston WWTP discharge to North Para River	27
	Bird-in-Hand WWTP discharge to Dawesely Creek–Onkaparinga catchment	418
	Hahndorf discharge to Hahndorf Creek–Onkaparinga catchment	315
	Heathfield discharge to Sturt River	631
	Victor Harbor discharge to Hindmarsh Reservoir and Inman River	806
Subtotal		2,197
potable water discharge	transfer from  Swan Reach–Stockwell Pipeline to the South Para River	2,423
Subtotal		2,423
Total		4,620

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.

The urban water supply system is one of three subcomponents of Adelaide's urban water system. The three subcomponents are the:

• urban water supply system
• wastewater system
• recycled water system.

During the 2012–13 year, Adelaide's urban water supply system relied on three important water sources. Imported River Murray water (line item 11.9 Delivery of water to urban water system under inter-region agreement) and surface water harvested from catchments within the Adelaide region (line item 11.12 Entitled diversion of allocated surface water to urban water system) made up the majority of the water sourced for urban supply; 42% and 35% respectively. Desalinated water (line item 11.6 Delivery of desalinated water to urban water system) made up the remaining 23% of inflows to the urban water supply system in the Adelaide region.

Potable water consumption within the region (line item 19.4 Delivery to urban water system users) was 137,028 ML during the 2012–13 year, representing 86% of all outflows from the urban water supply system. Smaller volumes of potable water were discharged to South Para Reservoir (line item 19.5 Discharge from urban water system to surface water: 2% of outflows) and transferred out of the region via normal operations in SA Water's service area (line item 19.11 Transfer of water outside region: 3% of outflows). Leakage from the water mains (line item 19.3 urban water system leakage to groundwater: 10%) made up the remaining urban water supply system outflows.

The following figure shows all the inflows and outflows for the urban water supply system. For more detail on a particular flow associated with the urban water supply system, refer to the line item notes. A misbalance of 2,140 ML or 1.3% was calculated for the urban water supply system. This misbalance may be due to a number of factors such as metering inaccuracies, unaccounted losses and inaccuracies in the estimation of certain volumes.

Schematic diagram of water inflows and outflows for Adelaide's urban water supply system during the 2012–13 year; line item numbers are provided in brackets

The wastewater system is one of three subcomponents of Adelaide's urban water system. The three subcomponents are the:

• urban water supply system
• wastewater system
• recycled water system.

In the Adelaide region, wastewater is collected (line item 11.4 Wastewater collected) from users and treated by SA Water at one of their wastewater treatment plants.

During the 2012–13 year the majority (64%: line item 19.7 Wastewater discharge outside of region) of treated wastewater was discharged to sea; approximately 32% was recycled (see recycled water system overview) and the remaining portion was either discharged to surface water (2%: line item 19.5 Discharge from urban water system to surface water) or lost during wastewater treatment processes (2%: part of line item 19.20 Other urban water system decreases).

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. The small misbalance shown (1.5%) can be attributed to metering inaccuracies, unaccounted losses and inaccuracies in the estimation of the recycled water on-site in process use.

Note that volumes annotated with an asterisk (*) indicate flows between subcomponents of the urban water system 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 recycled water system during the 2012–13 year; line item numbers are provided in brackets

Supervisory Control and Data Acquisition (SCADA) database or manual field instrument readings, stored in the MetDaily file.

SA Water.

Metered potable water discharge (transfer) from Swan Reach–Stockwell Pipeline to the South Para River for the 2012–13 year was obtained from SA Water's SCADA database and/or MetDaily file.

Nil.

The uncertainty estimate was not quantified.

WWTP records and Supervisory Control and Data Acquisition database (SCADA).

SA Water.

The metered discharge of wastewater to surface water was obtained from SA Water's WWTP records. Metered flows are either automatically logged by SCADA or manually read and recorded by plant operators.

The volume reported does not include any wastewater discharge from community waste management systems managed by local councils.

Uncertainty is +/– 10% based on meter calibrations.