19.11 Transfer of water outside of region
a. Transfer of water outside of region
The volume presented in the water accounting statements (146 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 2011–12 year Melbourne's urban water was sourced exclusively from surface water [11.12]; however in some years a very small proportion is sourced from groundwater [11.13]. While a desalination plant has been built to supplement Melbourne's urban water supply, this was not operational during the 2011–12 year.
Urban water consumption [19.4] of potable and non-potable water was 330,632 ML during the 2011–12 year, 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 [19.11]. Non-revenue water, including pipes bursting [19.2], background leakage [19.3] and other losses [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 2011–12 year. Line item numbers are provided in brackets.
A small misbalance (0.1%) is shown in the previous figure and can be attributed to possible differences in metering accuracies and unaccounted losses associated with water intake and supply.
The volume of water diverted from Mount Macedon to Woodend is metered and read weekly.