Melbourne
19.20 Other urban water decreases

Supporting Information

The volume presented in the water accounting statements (9,318 ML) represents the volume of non-revenue water from retail water authorities in the Melbourne region during the 2010–11 year.

The volume does not include leakage to groundwater or losses to the landscape, including pipe bursts from potable water supplies.

Non-revenue water from retail water authorities

Water authority

Volume (ML)

City West Water

 2,238

South East Water

3,657

Yarra Valley Water

3,423

Total

9,318

Quantification Approach

City West Water

Data Source

City West Water: database.

Provided by

City West Water.

Method

This item represents a component of the volume of non-revenue water. Non-revenue water is calculated as bulk supplied water minus metered and billed domestic and nondomestic water consumption. Non-revenue water may be broken into four components, authorised unbilled, apparent losses (unauthorised), apparent losses (metering) and reals losses (bursts, leaks and background losses).

The volume presented was calculated by subtracting real losses from the total non-revenue water.

Assumptions, Limitations, Caveats and Approximations

This item is calculated from other figures, and its accuracy can be inferred from the other fields used to calculate the figures. 

Uncertainty Information

Uncertainty is estimated to be +/– 5%.

South East Water

Data Source

South East Water: database.

Provided by

South East Water.

Method

The volume presented was calculated by subtracting leakage and pipe-bursts from the total volume of non-revenue water (bulk water supplied minus water sales).

Assumptions, Limitations, Caveats and Approximations

Non-revenue water includes infrastructure leakage, pipe burst, thefts and leak allowances.

Uncertainty Information

Water Industry Regulatory Audits 2011, October 2011 (Water Industry Regulatory Audits 2011) indicated that reliability and accuracy for metered volume of potable water delivered is +/– 5%.

Yarra Valley Water

Data Source

Yarra Valley Water: 2010 and 2011 potable water balance.

Provided by

Yarra Valley Water.

Method

The volume of non-revenue potable water remaining was estimated by subtracting volume of non-revenue water due to real losses (pipe bursts and leakage) from the total non-revenue water volume (13,712 ML) during the 2010–11 year.

Assumptions, Limitations, Caveats and Approximations

Nil.

Uncertainty Information

Estimated uncertainty is +/– 10%.

Comparative year

There was no corresponding line item reported in the 2010 Account. The restated comparative year volume is unquantified.