Adelaide
19.20 Other urban water system decreases

Supporting information

a. Other urban water system decreases

The volume reported (1,591 ML) represents decreases from the urban water system due to process losses from wastewater treatment plants (WWTP) as shown in the following table.


Wastewater treatment plant losses during the 2012–13 year
WWTP Inflow (ML) Outflow (ML) Process loss (ML)
Aldinga 634 629 5
Angaston 153 113 40
Bird-in-Hand1 472 584 0
Bolivar   51,353 50,338 1,015
Bolivar High Salinity 8,405 7,874 531
Christies Beach2 10,590 11,094 0
Glenelg3 17,471 17,677 0
Gumeracha4 41 42 0
Hahndorf 318 318 0
Heathfield 631 631 0
Myponga5 41 42 0
Victor Harbour6 934 980 0
Total 91,043 90,322 1,591

1-6
A negative process loss was reset to zero.

b. Wastewater system overview

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
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

Quantification approach

Wastewater treatment process losses

Data source

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

Provided by

SA Water.

Method

The metered inflow to and outflow from WWTPs were obtained from SA Water's WWTP records. Metered flows are either automatically logged by SCADA or manually read and recorded by plant operators. The WWTP loss was calculated as the difference between the metered inflow and outflow. Negative losses were reset to zero before summing up individual wastewater treatment plant losses.

Assumptions, limitations, caveats and approximations

  • The volume reported does not include any wastewater losses from community waste management systems managed by local councils.
  • Volume includes some wastewater collected from outside the Adelaide region and delivered to the Bird-in-Hand WWTP; however, this volume is negligible.

Uncertainty information

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