Sydney
19.4 Delivery to urban water system users
Supporting information
a. Urban water supply system overview
The urban water supply system is one of three sub-components of Sydney's urban water system. The three sub-components are the:
- Urban water supply system
- Wastewater system
- Recycled water system.
There are two main sources of water for Sydney's urban water supply system:
Urban water consumption (19.4) was 489,557 ML during the 2011–12 year, representing 48% of all urban water supply system outflows. The remaining urban water was reported as being lost through leakage to landscape (19.2) and operational losses (19.20).
The following figure shows all the inflows and outflows associated with 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.

The Sydney region's urban water supply system using data from Sydney Water Corporation, Shoalhaven City Council and Wingecarribee Shire Council
b. Recycled water system overview
The recycled water system is one of three sub-components of Sydney's urban water system.
In the Sydney region, approximately 8% of the treated wastewater from the wastewater system was recycled.
During the 2011-12 year, approximately 37% of the recycled water produced was supplied to private users for residential, industrial, agricultural or commercial use (19.4). Approximately 34% of the recycled water was used on-site at wastewater treatment plants throughout the region; the remaining 29% was discharged to surface water (19.5).
The following figure shows all the inflows and outflows associated with the urban water supply system. A small misbalance (6%) between total inflows and outflows is primarily due to flow meter errors and unaccounted losses.
For more detail on a particular flow associated with the recycled water system, refer to the line item notes. 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.

The Sydney region's recycled water system using data retrieved from Sydney Water Corporation and Shoalhaven City Council
c. Delivery to urban water users
The volume of water supplied through the urban system in 2011–12 was 489,557 ML.
A breakdown of potable, nonpotable and recycled water supplied through the urban system is provided in the following table.
|
Sydney Water Corporation (ML) |
Shoalhaven City Council (ML) |
Wingecarribee Shire Council (ML) |
Total water supplied (ML) |
Potable water supplied for residential use |
312,641 |
5,602 |
4,093 |
322,336 |
Potable water supplied for commercial, industrial and municipal use |
97,627 |
3,179 |
584 |
101,390 |
Potable water supplied for other uses |
29,420 |
562 |
141 |
30,123 |
Potable water supplied for agriculture and/or individual irrigation |
|
|
|
|
Non-potable water supplied for residential use |
0 |
5 |
0 |
5 |
Nonpotable water supplied for commercial, industrial and municipal use |
0 |
2,236 |
0 |
2,236 |
Non-potable water supplied for other uses |
|
28 |
0 |
|
Recycled water supplied for commercial, industrial and municipal use |
9,683 |
38 |
35 |
9,756 |
Recycled water supplied for agricultural/individual irrigation |
5,187 |
671 |
0 |
5,858 |
Recycled water supplied for residential use |
1,873 |
0 |
0 |
1,873 |
Recycled water used in process |
15,823 |
0 |
0 |
15,823 |
Total |
472,254 |
12,321 |
4,982 |
489,557 |
Quantification approach
Shoalhaven City Council – supply of potable water
Data source
Provided by
Method
Shoalhaven City Council used the total metered volume from water billing records to determine the volume of potable water supplied.
Assumptions, limitations, caveats and approximations
Uncertainty information
The volume is based on measured data and the water balance. Estimated uncertainty based on meter accuracy and professional judgment is +/– 2%.
Sydney Water Corporation – supply of potable water
Data source
Provided by
Method
The Sydney Water Corporation uses a water balance approach to determine volume of potable water supplied from the potable water supply system. The water balance is a reconciliation of the volume of water produced by the water treatment plants with all known and estimated end uses.
Assumptions, limitations, caveats and approximations
Uncertainty information
The volume is based on measured data and the water balance. Estimated uncertainty based on meter accuracy and professional judgment is +/– 2%.
Sydney Water Corporation – supply of potable water for other use
Data source
Provided by
Method
This item represents the total volume of potable water supplied other than for residential, commercial, industrial and municipal use. The volume includes the following components derived from water balance calculations and the measured data at each water treatment plant. The water balance is a reconciliation of the volume of water produced by the water treatment plants with all known and estimated end uses.
|
Volume (ML) |
Source |
Billed metered primary producers |
1,710 |
Derived from the Water Efficiency Report, Table 8 |
Billed metered other |
10,328 |
Derived from the Water Efficiency Report, Table 8 |
Billed unmetered |
2,314 |
Estimate used in water balance in the Water Efficiency Report Table 8 |
Unbilled metered and unbilled |
5,004 |
Derived from the Water Efficiency Report, Table 8 |
Unauthorised |
481 |
Estimate used in water balance in the Water Efficiency Report, Table 7 |
Meter under-registration |
8,623 |
Estimate used in water balance in the Water Efficiency Report, Table 7 |
Water balance–billing cycle |
716 |
Difference between the water balance used in the Water Efficiency Report, Table 7 and the measured data at each water filtration plant. |
Unexplained difference |
244 |
Unexplained difference |
Total |
29,420 |
|
Assumptions, limitations, caveats and approximations
The component 'billed metered primary producers' (1,710 ML) is taken as 'supply to agriculture', and total of the remaining components (27,710 ML) is taken as 'other supplies including non-metered, unbilled components'.
Uncertainty information
The uncertainty was not quantified.
Wingecarribee Shire Council – supply of potable water
Data source
Provided by
Method
This item represents the total volume of potable water supplied for residential, commercial, industrial and municipal use. The total volume is derived from data collected from calibrated outflow meters at water treatment plants, minus the volume estimated as leakage and bursts.
Assumptions, limitations, caveats and approximations
Information required to separate the volume of potable water supplied to residential; and commercial, industrial and municipal use categories are not available.
Uncertainty information
The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 7%.
Comparative year
The volume stated for the 2011 Account incorrectly did not recognise the volume of water that was delivered from the recycled water system. The volume of recycled water was 32,148 ML. Consequently, the volume has been restated from 474,594 ML to 506,242 ML.