Melbourne
11.13 Entitled extraction of allocated groundwater to urban water system

Supporting information

a. Entitled extraction of allocated groundwater to urban water system

The line item value for the 2012-13 year is (66 ML) which represents the volume of water extracted from groundwater for urban water supply. During the 2012–13 year Western Water reported 66 ML and South East Water reported a zero volume of groundwater extracted under their groundwater entitlements.

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

South East Water

Data source

Internal database.

Provided by

South East Water.

Method

The volume reported is the smart meter (real-time) metered volume of water extracted from the Lang Lang bore.

This water is taken from groundwater to supply water tankers for irrigation. The stand pipe that extracts the water from the groundwater bore has been closed because of low demand, as a result of South East Water providing alternative solutions and high rainfall.

Assumptions, limitations, caveats and approximations

Assumes the meters and readings are accurate.

Uncertainty information

Meter type: Elster R2000 100 mm; uncertainty is +/–2%.

Western Water

Data source

IT database.

Provided by

Western Water.

Method

This volume was calculated as the total metered volume of groundwater taken from Lancefield Bore 3. Meter is located on a pipe between the bore and the water treatment facility. Meter readings are recorded daily. Groundwater from Lancefield Bore 2 was not supplied to the urban system because of poor water quality.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The uncertainty estimate is +/– 5% in accordance with manufacturer's annual bulk meter test.