Melbourne
19.11 Transfer of water outside of region

Supporting information

a. Transfer of water outside of region

The volume presented in the water accounting statements (250 ML) represents the volume of water transferred outside of the region from Mount Macedon to Woodend via Western Water's water supply infrastructure.

The transfer is part of the regular operations of Western Water in providing water to customers within their service area. The service area of Western Water overlaps with the boundary of the Melbourne region.

b. Urban water supply system overview

The urban water supply system is one of three sub-components of Melbourne's urban water system. The three sub-components are the:

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

During the 2012–13 year Melbourne's urban water was sourced mostly from surface water (line item 11.12), with a very small proportion sourced from groundwater (line item 11.13). While a desalination plant has been built at Wonthaggi to supplement Melbourne's urban water supply, this was not required to supply any water during the 2012–13 year.

Urban water consumption (line item 19.4) of potable and non-potable water was 361,339 ML during the 2012–13 year, comprising of 360,931 ML of potable water and 408 ML of non-potable water, representing almost 90% of all urban water supply system outflows. A very small volume of water was transferred out of the region via normal operations in Western Water's service area (line item 19.11). Non-revenue water, including pipes bursting (line item 19.2), background leakage (line item 19.3) and other losses (line item 19.20), 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.

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

A small misbalance 127 ML from the previous figure can be attributed to possible differences in metering accuracies and unaccounted losses associated with water intake and supply.

Quantification approach

Data source

Information Technology database.

Provided by

Western Water.

Method

The volume of water diverted from Mount Macedon to Woodend is metered and read weekly.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The uncertainty estimate was not quantified.