Melbourne
11.13 Entitled extraction of allocated groundwater to urban water system

The volume reported in the water accounting statements (0 ML) represents the volume of water extracted from groundwater for urban water supply. During the 2011–12 year both South East Water and Western Water reported a zero volume of groundwater extracted under their groundwater entitlements.

The zero volume reported by South East Water is inconsistent with records from the Victorian Water Register. The register records that South East Water extracted a volume of 3 ML under their entitlement to Koo Wee Rup Water Supply Protection Area—groundwater. It is unclear how this inconsistency arose, however given the small volume the impact on the account is not considered material.

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.

Internal database.

South East Water.

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.

Assumes the meters and readings are accurate.

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

IT database.

Western Water.

This volume is calculated as the total metered volume of groundwater taken from two Lancefield bores. Meters are located on pipes between the bores and the water treatment facility. Meter readings are recorded daily.

Groundwater usage by Western Water during the 2011–12 year

Bore	Usage (ML)
Lancefield Bore 2	0
Lancefield Bore 3	0

Nil.

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

In the 2011 Account, it was not possible to separate urban and non-urban entitlements to groundwater. Therefore, the volume of groundwater extracted for all groundwater entitlements was reported at line item 18.11 'Groundwater allocation extraction'.

In the 2012 Account, data provided has enabled urban water entitlements to groundwater to be reported separately in the Melbourne Account. Consequently, the volume has been restated as 12 ML.

Comparative year information for line item 11.13 Entitled extraction of allocated groundwater to urban water system

Groundwater management unit	Entitlement holder	2012 Account volume for the 2010–11 year (ML)	2011 Account volume the 2010–11 year (ML)
Koo Wee Rup Water Supply Protection Area—groundwater	South East Water	4	reported as part of line item 18.11
Lancefield Groundwater Management Area	Western Water	8	reported as part of line item 18.11
Total allocation announcements		12