Melbourne

No volume is recognised in the water accounting statements (–) despite the existence of potable water export from Melbourne region. This movement of water is already captured at Line item 14.9 Transfer-out of surface water under inter-basin agreement.

Non-potable water was exported from the water distribution system to Gippsland Water and to Western Water service areas (around Woodend) outside of the Melbourne region. Gippsland Water receives water from the Tarago catchment to supply districts mainly to the east of the Melbourne region. The service area of Western Water includes towns both inside and outside the Melbourne region. The town of Woodend, for example, lies outside the Melbourne region but receives water sourced from within the region.

The table below shows the breakdown of water exported from the water distribution system within the Melbourne region during 2009–10.

Data source

Melbourne Water: Waterworks database.
Western Water: IT database.

Data provider

Melbourne Water and Western Water.

Method

The total volume of water transferred out of the region was the sum of a number of components that are provided from different water utilities as described below.

Melbourne Water
This item represents the total metered volume of non-potable water provided to Gippsland Water from the Tarago catchment at the following locations:

• Tarago–Westernport Pipeline at Rokeby (to supply Warragul and Drouin)
• Tarago Reservoir (to supply Neerim South and Noojee).
  

Western Water
This item represents the total metered volume of non-potable water exported from Western Water. Meters are located on inflow pipelines to Woodend reservoirs. Weekly readings are taken from these meters.

Uncertainty

Melbourne Water: Estimated uncertainty is ungraded.
Western Water: Derived from metered data. Estimated uncertainty is +/–5%.
The uncertainty value provided by Western Water refers to the Essential Services Commission’s standard confidence grades, as detailed in its June 2005 guideline for Approving, Conducting and Reporting Audits for Victorian Water Businesses (ESC 2005). Refer to Summary Audit Report – Regulatory Audit of AGL Energy Limited, October 2010 (ESC 2010) prepared for Western Water.

Approximations, assumptions, caveats/limitations

Nil.