Sydney
19.2 Leakage to landscape

Volumes shown in the following table have been recorded as leakage from the urban water system to the landscape.

Breakdown table of leakage volumes from each urban utility

Water authority	Recorded leakage volume from urban system to landscape (ML)
Shoalhaven City Council	382
Sydney Water Corporation	38,620
Wingecarribee Shire Council	204
Total	39,206

 

Data on leakage from the urban water system to the landscape are not available for the systems operated by other water utilities.

 

NSW Water Supply and Sewerage: Performance Monitoring Report 2010–11. (Access through the 'Performance monitoring' webpage of the NSW Office of Water. The report will be included on the webpage from June 2012.

Shoalhaven City Council.

The number provided by the council is the total loss and leakage from the urban potable water supply and nonpotable water (raw water diverted from the rivers) supply systems. This volume was estimated as 9% of the total consumption via the urban potable water and nonpotable water supplies.

• Data represents total leakage and loss from potable and nonpotable water supply systems, as the breakdown between the two supplies is not available.
• Total volume of estimated loss and leakage from the urban water supply system is to be taken as an input to the landscape water store, as the breakdown of leakage components entering landscape and groundwater stores are not available separately.
• The uncertainty estimate is based on the total leakage factor for the whole of the area managed, and may not specifically relate to the City Council area within the Sydney region (i.e. the value provided is likely to be an overestimate).

The volume is based on measured data from a sample area and extrapolated to other areas. Estimated uncertainty based on meter accuracy, professional judgment and organisational practice is +/– 5%.

Tables 9 and 10 of Sydeny Water Corporation's (SWC) Water Efficiency Report 2010–11.

SWC.

SWC used the global water balance approach to determine leakage and loss from the potable water supply system. The water balance is a reconciliation of the volume of water produced by the water treatment plants (WTPs) with all known and estimated end uses. The remainder is classified as leakage.

• Data represents total leakage and loss from potable and nonpotable water supply systems, as the breakdown between the two supplies is not available.
• Total volume of estimated loss and leakage from the urban water supply system is to be taken as an input to the landscape water store, as the breakdown of leakage components entering landscape and groundwater stores are not available separately.

Measured and estimated data used in the water balance for the calculation contribute to uncertainty of leakage volumes. As leakage volumes calculated via a water balance are proportionally small, residual errors tend to be magnified. The uncertainty band on leakage as calculated by an annual water balance is estimated to be about +/– 25% with a 95% confidence limit.

Data spreadsheets.

Wingecarribee Shire Council.

The value represents the total volume of leakage and losses from the potable water supply system. The volume is based on the water balance method, where potable water production figures from the WTPs are configured with the consumption figures obtained by flow meter readings at listed properties.

• Data represents total leakage and loss from potable and nonpotable water supply systems, as the breakdown between the two supplies is not available.
• Total volume of estimated loss and leakage from the urban water supply system is to be taken as an input to the landscape water store, as the breakdown of leakage components entering landscape and groundwater stores are not available separately.

The volume is based on measured data. Estimated uncertainty based on meter accuracy, professional judgment and organisational practice is +/– 20%.

The following table compares the value at 30 June 2010 reported in this account with the corresponding value reported in the 2010 Account.

 

Comparative information from the 2010 Account for line item 19.2

2011 Account line item	2010 Account line item	Value reported in the 2010 Account (ML)	Value reported in the 2011 Account (ML)	Additional information
19.2 Leakage to landscape	20.2.1 Leakage from water distribution system to landscape	36,249	36,249	Change in line item name and number