Melbourne

Numbers in this note are for the Melbourne region as a whole. They are compiled from various sources. Please see the urban water notes for each of the below organisations for data sources and further information.

Data source organisations referred to below are:

• City West Water (CWW)
• Melbourne Water (MW)
• South East Water (SEW)
• Western Water (WW)
• Yarra Valley Water (YVW).
  
  

Figure 1. Urban note – summary of the Melbourne region*

*All volumes are in megalitres (ML)

The differences between urban water distribution system components are attributed to unaccounted water losses, and limitations in the calculations of volumes sourced, treated and supplied for consumption and other uses.

Note 1: Direct comparison of the total volume of water supplied (via the urban water supply system and the recycled water supply system) and the total volume of wastewater generated in a region is not feasible due to data limitations on:

• volume used for outdoor and irrigation purposes, part of which enters the landscape or the groundwater store and not the wastewater system
• volume used for industrial purposes that may be exported from the region (e.g. beverage industry)
• volume of water entering the wastewater system via the use of individually taken water sources (e.g. rainwater tanks)
• volume of wastewater treated via the privately owned wastewater treatment systems
• ingress of groundwater and stormwater into the wastewater systems, and exfiltration or overflow from the wastewater systems.

Note 2: Total volume of water sourced for the urban water supply system (IN): 364,414 ML

Total supplied by the urban water supply system (OUT) = 362,468 ML. Total volume of water usage via urban water supply system (322,660 ML); losses (38,244 ML), exports out of the region (681 ML), supply to Southern Rural Water for irrigation in Bacchus Marsh (733 ML) and (5 ML); volume taken from Tarago River for Southern Rural Water supply to farmers (150 ML)

IN – OUT difference (1,946 ML) is likely to be due to unaccounted losses and limitations in the calculations of volumes sourced, received and supplied by water authorities.

Note 3: Water usage components A plus B (332,488 ML):

• Component (A): Water usage via supplies from the urban water supply systems of urban retail water authorities = 322,660 ML
• Component (B): Water usage via supplies from the recycled water supply systems of urban retail water authorities = 9,828 ML

Note 4: (C) Wastewater treated (303,989 ML); (D) Effluent discharge (216,997 ML) + recycled water produced (86,639 ML) = 303,636 ML

This difference between (C) and (D) is likely to be due to the differences in metering accuracies and unaccounted losses.

Note 5: Total recycled water produced (86,639 ML) = recycled water for supplies (44,400 ML) + total volume of recycled water used on-site (42,239 ML).

Total volume of recycled water used on-site (42,239 ML) = volume used on-site within process (17,902 ML) + volume used on-site (24,337 ML).

Note 6: Recycled water supplies

IN = recycled water volume for supplies (44,400 ML) + recycled water received from other organisations in the region (270 ML) = 44,670 ML.

OUT = recycled water supplied via urban retail water authorities (9,828 ML) + recycled water supplied from Melbourne Water to Southern Rural Water for (a) irrigation (17,563 ML) plus (b) Werribee tourist precinct use (102 ML) + Melbourne Water (conservation flows) to environment (17,199 ML) = 44,692 ML.

IN – OUT = –22 ML, which is attributed to differences in metering accuracies and locations relevant to recycled water supplied and received by different organisations and water authorities.

Note 7: Recycled water received from other organisations in the region (270 ML) represents the recycled water purchased from TopAq Eastern Irrigation Scheme (EIS) and Inkerman Greywater Treatment Plant.

NA = not applicable

The difference between the total volume of water sourced (364,414 ML) and the total volume supplied by the urban water supply system (362,468 ML) is likely to be due to unaccounted losses and limitations in the calculations of volumes sourced, received and supplied by water authorities.

Total volume supplied by the urban water supply system (362,468 ML) includes:

1. water usage via urban water supply system (322,660 ML in Table 2)
2. losses (38,244 ML in Table 5)
3. exports out of the region (681 ML, items 1, 2 and 4 in Table 2a)
4. supply to Southern Rural Water for irrigation in Bacchus Marsh (733, item 6 in Table 2a)
5. volume taken from Tarago River for Southern Rural Water supply to farmers (150 ML – item 5 in Table 2a).

* Includes supplies of non-potable water to residential, commercial, industrial and municipal usage from South East Water

* Export to outside the region totals 681 ML (items 1, 2 and 4)

** Supply within the Melbourne region not serviced via other water authorities

* Recycled water purchased from TopAq EIS and recycled water received from Inkerman Greywater Treatment Plant

** Supply by Melbourne Water to urban retail water authorities is balanced by recycled water received by South East Water and City West Water. The supply to the region is included in the urban water authority recycled water supplies for use (items 4–6)