Melbourne

Urban water – Melbourne Water

Summary of water distribution system

Figure 1 and tables 1–5 summarise the water distribution for Melbourne Water for 2009–10. The tables provide a breakdown for values shown in Figure 1. Notes for the values provided in tables 1–5 are available after Table 5.

Figure 1: UrbanSAT – summary of Melbourne Water

Figure 1. Urban note – summary of Melbourne Water*

*All volumes are in megalitres (ML)

Differences between the 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, 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: Part of the wastewater generated in the Melbourne region is treated by the urban retail water authorities.

Note 3: Wastewater treated (271,108 ML) = effluent discharge (196,290 ML) + total recycled water produced (74,818 ML).

Note 4: Total recycled water produced (74,818 ML) = recycled water for supplies (36,302 ML) + total volume of recycled water used on-site (38,516 ML).

Note 5: Recycled water supplies (36,302 ML) = recycled water supplied to other organisations (19,103 ML) + recycled water supplied to the environment (17,199 ML).

Note 6: Recycled water supplied to other organisations (19,103 ML) = Part 1: Supply to Southern Rural Water for irrigation (17,563 ML) + Part 2: Supply to urban retail water authorities (1,438 ML) + Part 3: supply to Southern Rural Water for Werribee Tourist Precinct use (102 ML).

Table 1: Sources of water supplied to the water authorities
Sources of water		Volume (ML)	Note
Delivered via the water supply system (connected areas)	Water sourced from external entity	0
	Water sourced from surface water	363,470	MW_U1
	Water sourced from groundwater	0
	Water sourced from desalination	0
	Water sourced from recycle	(See table 4)
	Total water sourced to supply water authorities	363,470
Directly abstracted water *	Water sourced from surface water	-
	Water sourced from groundwater	-
	Water sourced from farm dam	-
	Water sourced from rainwater tank	-
	Total water directly sourced	-
Total water sourced (excluding recycled water)		363,470

* Data on directly abstracted water are unavailable or incomplete, and therefore not included.

Table 2: Total water exported or supplied to other water authorities
within the region
Item	Water provided	Volume (ML)	Note
1	Portable water provided to City West Water	90,995	MW_U7.a
2	Potable water provided to South East Water	125,239	MW_U7.b
3	Potable water provided to Yarra Valley Water	133,916	MW_U7.c
4	Potable water provided to Western Water	10,087	MW_U7.d
5	Non-potable water provided to Yarra Valley Water – water taken from Maroondah aqueduct as direct supply to customers	495	MW_U8.b
6	Non-potable water provided to South East Water – water taken from Bunyip River as direct supply to customers	84	MW_U8.c
Subtotal		360,816	Items 1 + 2 + 3 + 4 + 5 + 6
7	Non-potable water provided to Gippsland Water from Tarago (export out of the Melbourne region subaccount )	546	MW_8.a
Subtotal: Water provided to urban retail water authorities by Melbourne Water		361,362	Items 1 + 2 + 3 + 4 + 5 + 6 + 7
8	Non-potable water provided to Southern Rural Water – water taken from Tarago River for SRW supply to farmers	150	MW_U8.d
9	Potable water provided to Southern Rural Water via Western Water for supply to irrigators in the Bacchus Marsh Irrigation District	735	MW_U7.e
10	Total water exported or supplied to other water authorities within the region	362,247	Items 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9

Table 3: Wastewater
Item	Wastewater received and treated	Volume (ML)	Note
1	Wastewater received from within the region from other water authorities	271,739	MW_U20
2	Subtotal: wastewater treated	271,108	MW_U19
3	Wastewater treated for recycling	74,818	MW_U30
4	Wastewater (treated) discharged to surface water	0	-
5	Wastewater (treated) discharged to ocean	196,290	MW_U23
6	Subtotal: treated wastewater discharged	196,290	Items 4+ 5

Table 4: Recycled water
Item	Recycled water produced and supplied	Volume (ML)	Note
1	Total recycled water produced	74,818	MW_U30
2a	Recycled water use on-site at Western Treatment Plant	24,337	MW_U34.a
2b	Recycled water use on-site in-process use at Eastern Treatment Plant	14,179	MW_U34.b
3	Recycled water supplied to residential	0
4	Recycled water supplied to commercial, industrial and municipal	0
5	Recycled water export to agricultural	0
6	Recycled water supplied to environment	17,199	MW_U33
7	Recycled water supplied to artificial recharge	0
8	Recycled water supplied to other water authorities	19,103	MW_U29
9	Total recycled water supplied	36,302	Items 6 + 8

Table 5: Urban water supply system water losses from Melbourne Water operated infrastructure
Losses	Volume (ML)	Note
Losses from potable and non-potable water supplies	1,223	MW_U15 & U17
Losses from recycled water supplies	-
Total water losses	1,223

U1 Volume of water taken from surface water for water supply

MW_U1: 363,470 ML

Data source

Melbourne Water: Waterworks database.

Data provider

Melbourne Water.

Method

This item represents the total volume of surface water taken for water supply. The total volume is approximated as shown in tables 6 and 7.

Table 7: Volume of water provided to the urban retail water authorities by Melbourne Water
Item	Water supply	Volume (ML)	Note
1	Potable water provided to City West Water	90,995	U7.a
2	Potable water provided to South East Water	125,239	U7.b
3	Potable water provided to Yarra Valley Water	133,916	U7.c
4	Potable water provided to Western Water	10,087	U7.d
5	Non-potable water provided to Yarra Valley Water – water taken from Maroondah aqueduct as direct supply to customers	495	U8.b
6	Non-potable water provided to South East Water – water taken from Bunyip River as direct supply to customers	84	U8.c
	Subtotal	360,816
7	Non-potable water provided to Gippsland Water from Tarago (export out of the Melbourne region )	546	U8.a
	Total volume provided to urban retail water authorities from Melbourne Water	361,362

Table 8: Volume of water provided to Southern Rural Water by Melbourne Water
Item	Water supply	Volume (ML)	Note
8	Potable water provided to Southern Rural Water via Western Water for supply to irrigators in the Bacchus Marsh Irrigation District	735	U7.e
9	Non-potable water provided to Southern Rural Water – water taken from Tarago River for Southern Rural Water supply to farmers	150	U8.d
	Total volume provided to Southern Rural Water by Melbourne Water	885

Melbourne Water reported estimated proportions of water released from each of the seasonal reservoirs (Table 9) as an indication of the proportion of water intake from each reservoir to supply the total volume (derived as U1). This excludes items 5 and 6 from Table 7, and Item 9 from Table 8.

Table 9: Proportion of water released from seasonal reservoirs
Release location	Percentage of total released
Cardinia	24
Silvan	30
Winneke	30
Tarago	4
Yan Yean	<1
Greenvale	11
Yarra Valley (small treatment plants)	<1
Total	100

Uncertainty

In Table 9, meters are generally ultrasonic flow meters for larger pipes (greater than 600 mm diameter) and magnetic flow meters for smaller pipes (less than 600 mm diameter). Both types of meters have an accuracy of +/–1% as reported by the manufacturers.

Assumptions, approximations and caveats/limitations

The volume surface water taken for water supply cannot be determined directly.

U5 Volume of non-potable water imported into the region

MW_U5: 84,400 ML

This water is imported to the connected surface water stores within the Melbourne region, via the Sugarloaf intake, Thompson transfer, and import from Silver and Wallaby catchments, as detailed in the table below.

Data source

Melbourne Water: WaterWorks database.

Data provider

Melbourne Water.

Method

The total volume is derived as shown below.

Import source	Volume per year (ML)
Sugarloaf intake from Goulburn River	16,700
62,400
Import from Silver and Wallaby catchments*	5,300
Total	84,400

*estimated

Sugarloaf intake from Goulburn River

Data capture: telemetry.

Measurement description: Water is diverted from the Goulburn River to the Sugarloaf Pipeline at the Sugarloaf Pipeline Pump Station.

Measurement device: The flow from the pump station is measured using a Siemens Sitrans SONOKIT dual-beam ultrasonic flow meter.

Accuracy: +/–1%.

Thomson transfer to Upper Yarra Reservoir

Data capture: telemetry.

Measurement description: The crest of the spillway chute behaves as an Ogee weir. The depth of water flowing over the weir is measured using a Mindata 2100P level sensor and is converted to flow using a stage-discharge relationship.

Measurement device: Mindata 2100P level sensor.

Accuracy: +/–2%.

Import from Silver and Wallaby catchments (estimated)

Data capture: telemetry.

Measurement description: Toorourrong Reservoir is supplied from both Silver and Wallaby creeks (in the Goulburn Basin), and the east branch of the Plenty River (in the Yarra Basin). Diversions from Silver and Wallaby creeks are estimated as 64% of the Clearwater channel flow, and from Plenty River as 36% of the Clearwater channel flow. Clearwater channel flow is measured at the Toorourrong Reservoir outlet using a level transmitter and rating table. These percentages have been based on historical records of catchment run-off.

Measurement device: level transmitter.

Accuracy: +/–1%.

Assumptions, approximations and caveats/limitations

Nil.

U7 Volume of potable water exported or supplied to other water authorities within the region

MW_U7: 360,972

Data source

Melbourne Water: Waterworks database.

Data provider

Melbourne Water.

Method

This item represents the total metered volume of potable water provided to other water authorities by Melbourne Water. Meters are mostly operated by Melbourne Water, and are located at the interface between Melbourne Water and each of the retail water authorities. The volume that is ‘billed’ to these authorities by the many billing meters operated by Melbourne Water is considered the reported volume.

The total volume is derived by the addition of the components described in the following table.

Component	Portable water export	Volume (ML)
U7.a	Potable water provided to City West Water	90,995
U7.b	Potable water provided to South East Water	125,239
U7.c	Potable water provided to Yarra Valley Water	133,916
U7.d	Potable water provided to Western Water	10,087
U7.3	Potable water provided to Southern Rural Water via Western Water for supply to irrigators in the Bacchus Marsh Irrigation District	735
U7	Total potable water exported or supplied to water authorities within the region	360,972

Uncertainty

Billing meters are generally ultrasonic flow meters for larger pipes (greater than 600 mm diameter) and magnetic flow meters for smaller pipes (less than 600 mm diameter). Both types of meters have a notional accuracy of +/–1%.

Assumptions, approximations and caveats/limitations

Although water is provided to Southern Rural Water for irrigation purposes in the Bacchus Marsh Irrigation District, this water has been fully treated for consumptive use and is thus considered to be potable water. This is not a usual practice and was implemented in the 2009–10 year as a drought response measure.

Although Gippsland Water received water from the Tarago Basin in 2009–10 (546 ML), this water was not treated and thus considered non-potable.

U8 Volume of non-potable water exported or supplied to other water authorities within the region

MW_U8: 1,275 ML

Data source

Melbourne Water: Waterworks database.

Data provider

Melbourne Water.

Method

This item represents the total metered volume of non-potable water provided to water authorities by Melbourne Water. The total volume is derived by the addition of the components described in the following table.

Component	Water export	Volume (ML)
U8.a	Non-potable water from Tarago to Gippsland Water (export out of the Melbourne region)	546
U8.b	Non-potable water to Yarra Valley Water – water taken from Maroondah aqueduct as direct supply to customers	495
U8.c	Non-potable water to South East Water – water taken from Bunyip River as direct supply to customers	84
U8.d	Non-potable water to Southern Rural Water – water taken from Tarago River for Southern Rural Water supply to farmers	150
U8	Total non-potable water exported or supplied to other water authorities within the region	1,275

Gippsland Water accessed the volume of non-potable water exported from the Tarago Basin, which is in the Melbourne region, to Gippsland Water, which is outside the Melbourne region, at the following locations:

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

Uncertainty

Melbourne Water releases water from the Tarago Reservoir into the Tarago River for Southern Rural Water irrigators. The point of release is a source of uncertainty.

Assumptions, approximations and caveats/limitations

Not disclosed.

U15 Background leakage from potable water supply system

and

U17 Losses (e.g. pipe bursts) from potable water supply system

MW_U15 + U17: 1,223 ML

The combined volume of U15 and U 17 is reported because the information is not available to estimate these components separately.

Data source

Melbourne Water: Waterworks database.

Data provider

Melbourne Water.

Method

This item represents the estimated losses and leakage from the water supply systems managed by Melbourne Water from intake of water for treatment from seasonal storages to the delivery of potable water to other water authorities. The total volume is derived by the addition of the components described in the following table.

Losses from potable water supply system	Volume (ML)
Loss of potable water from major pipes	33
Loss of potable due minor leaks	79
Loss of potable water through service reservoir and tanks water	249
Loss of potable water though operational activities	862
Total	1,223

The National Water Account 2010 uses the following definitions:

• leakage is the slow, diffuse, continuous egress of water from pipes
• burst is the fast, point-source, event-based egress of water from pipes
• total loss is the sum of leakage and burst.

Potable water lost from pipes – major pipes

A major loss event is when a water main requires isolation for repair works. This is generally when the leakage loss rate is greater than 1 ML/d.

Melbourne Water conducts separate investigations into all losses from major pipes. For each of these investigations, the total elapsed time, size of perforation and pressure of the leak is estimated to allow water loss to be calculated.

In 2009–10, total loss through major pipe bursts was estimated to be 33 ML.

Potable water lost from pipes – minor leaks

A minor loss event is when a water main does not require isolation for repair works. This is generally when the leakage loss rate is less than 1 ML/d.

For losses from minor pipes, Melbourne Water has adapted an estimation method determined by the Australian Water Association. Melbourne Water keeps records of the time taken to repair each leak in its system. In 2009–10, the total loss through minor pipe bursts was estimated to be 79 ML.

Potable water lost through service reservoir and tank dewatering

Dewatering is undertaken intermittently on service reservoirs and tanks to allow for cleaning and other maintenance works.

Service reservoirs and tanks have height meters that can accurately gauge current storage levels and water lost through dewatering. In 2009–10, total loss due to dewatering of service reservoirs and tanks was estimated to be 249 ML.

Potable water lost through operational activities

Water can be lost through system shutdowns and flushing operations, and the volume of water required to carry out such operational activities is calculated. In 2009–10, total loss through operational activities was estimated to be 862 ML.

Uncertainty

Not disclosed.

Assumptions, approximations and caveats/limitations

Leakage from the non-potable water supplies is not included.

Non-potable water lost from aqueducts are not included as these are located upstream of the seasonal storages.

U19 Volume of wastewater treated

MW_U19: 271,108 ML

Data source

Melbourne Water: ASPEN and supervisory control and data acquisition (SCADA) databases.

Data provider

Melbourne Water.

Method

This item represents the total metered volume of wastewater treated by Melbourne Water. Wastewater is metered at the influent pump stations of both the Eastern Treatment Plant and Western Treatment Plant. The treatment plants have primary inflow metering, as well as additional metering to record the inflows should the primary metering be offline.

Volume of wastewater treated	Volume (ML)
Volume of wastewater treated at the Western Treatment Plant	147,985
Volume of wastewater treated at the Eastern Treatment Plant, including 14,179 ML of wastewater treated and recirculated back into the treatment plant for in-process use	123,123
Total	271,108

The Western Treatment Plant defines the volume of wastewater treated (147,985 ML) as the volume of wastewater collected (162,795 ML) less evaporative losses (14,810 ML).

The Eastern Treatment Plant defines the volume of wastewater treated (123,123 ML) as the volume of wastewater collected (108,944 ML) plus the amount of recycled water that is recirculated back into the treatment plant for in-process use (14,179 ML).

Uncertainty

Wastewater inflows are measured using magnetic flow meters, which are assumed to be accurate to within +/–5%.

Assumptions, approximations and caveats/limitations

The Western Treatment Plant logs data daily and reports quarterly. The Eastern Treatment Plant logs data daily and reports monthly. Thus, metering periods align with the reporting period.

U20 Volume of wastewater imported or received from water authorities within the region

MW_U20: 271,739 ML

Data source

Melbourne Water: ASPEN and supervisory control and data acquisition (SCADA) databases.

Data provider

Melbourne Water.

Method

This item represents the total metered volume of wastewater received by Melbourne Water. Wastewater is metered at the influent pump stations of both the Eastern and Western treatment plants. These plants have primary inflow metering, as well as additional metering to record the inflows should the primary metering be offline.

Volume of wastewater received	Volume (ML)
Volume of wastewater received at the Western Treatment Plant	162,795
Volume of wastewater received at the Eastern Treatment Plant	108,944
Total volume of wastewater received	271,739

Uncertainty

Wastewater inflows are measured using magnetic flow meters, which are assumed to be accurate to within +/–5%.

Assumptions, approximations and caveats/limitations

The total volume includes 57 ML/year of wastewater, which is an estimated volume based on historical averages, from City West Water that enters the Western Treatment Plant downstream of the billing meter.

The Western Treatment Plant logs data daily and reports quarterly. The Eastern Treatment Plant logs data daily and reports monthly. Thus, metering periods align with the reporting period.

U23 Volume of (treated) wastewater discharged to sea or out of entity

MW_U23: 196,290 ML

Data source

Melbourne Water: ASPEN and supervisory control and data acquisition (SCADA) databases.

Data provider

Melbourne Water.

Method

This item represents the total volume of wastewater discharge to the sea from Melbourne Water’s wastewater treatment plants.

Wastewater discharged to sea	Volume (ML)
Volume of treated wastewater discharge to the sea from the Western Treatment Plant	93,663
Volume of treated wastewater discharge to the sea from the Eastern Treatment Plant	102,627
Total volume of wastewater discharge	196,290

Uncertainty

Not disclosed.

Assumptions, approximations and caveats/limitations

This item is determined using a mass-balance calculation of all wastewater collected, treated, stored and recycled. Therefore, uncertainty depends on the associated uncertainty of items U19, U20, U23, U29, U30, U33 and U34.

U29 Volume of recycled water exported or supplied to other organisations within the region

MW_U29: 19,103 ML

Data source

Various utility databases (where they are receiving recycled water).

Data provider

Melbourne Water.

Method

This item represents the total metered volume of recycled water provided to water authorities from Melbourne Water’s wastewater treatment plants. All water that is recycled for supply to other water authorities is measured with magnetic flow meters at the interface of Melbourne Water and the receiving authority.

Recycled water supplied to water authorities		Volume (ML)
Part 1: Recycled water supplied to irrigation	Western Treatment Plant to Southern Rural Water – Werribee Irrigation District	12,381
	Eastern Treatment Plant to Eastern Irrigation Scheme	5,182
	Subtotal	17,563
Part 2: Recycled water supplied to urban retail water authorities	Western Treatment Plant to City West Water for usage via City West Water supplies	303
	Eastern Treatment Plant to South East Water to south eastern outfall – usage via South East Water supplies	1135
	Subtotal	1,438
Part 3: Recycled water supplied to Southern Rural Water	Western Treatment Plant to Southern Rural Water – Werribee Tourist Precinct use	102
Total		19,103

Uncertainty

Magnetic flow meters are used to measure these flows and are assumed to have an accuracy of +/–1 to +/–2%.

Assumptions, approximations and caveats/limitations

The Western Treatment Plant logs data daily and reports quarterly. The Eastern Treatment Plant logs data daily and reports monthly. Thus, metering periods align with the reporting period.

U30 Volume of recycled water produced from wastewater

MW_U30: 74,818 ML

Data source

Melbourne Water: ASPEN and supervisory control and data acquisition (SCADA) databases.
Various utility databases (where they are receiving recycled water).

Data provider

Melbourne Water.

Method

This item represents the total metered volume of recycled water produced by Melbourne Water’s wastewater treatment plants. This value is the total of all the individual recycled water uses from both the Eastern and Western treatment plants. All water that is recycled for supply to other water authorities is measured by the receiving authority with magnetic flow meters at the interface of Melbourne Water and the receiving authority.

Recycled water produced	Volume (ML)
Total recycled water produced at Western Treatment Plant	54,322
Total recycled water produced at Eastern Treatment Plant*	20,496
Total	74,818

* Includes wastewater treated and recirculated back into the treatment plant for with in-process use (14,179 ML).

Uncertainty

The accuracy assumed for this form of metering is assumed to be +/–5 to +/–10%.

Assumptions, approximations and caveats/limitations

As for U29, U33 and U34.

U33 Volume of recycled water supplied other than for residential, commercial, municipal and industrial uses

MW_U33: 17,199 ML

Data source

Melbourne Water: supervisory control and data acquisition (SCADA) database.

Data provider

Melbourne Water.

Method

This item represents the total metered volume of recycled water supplied for environment. Water recycled and used for conservation flows is metered using an ultrasonic level transmitter. This recycled is measured by Melbourne Water before being discharged to the Lake Borrie wetlands (Ramsar listed).

Recycled water supplied for environment	Volume (ML)
Volume of recycled water provided from the Western Treatment Plant as conservation flows to the Lake Borrie wetlands within the Western Treatment Plant	17,199
Total	17,199

Uncertainty

Ultrasonic level transmitters are used to measure flows and are assumed to have an accuracy of +/–5 to +/–10%.

Assumptions, approximations and caveats/limitations

Data are logged daily and reported quarterly, and thus metering periods align with the reporting period.

U34 Volume of recycled water used on-site or on-site in-process

MW_U34: 38,516 ML

Data source

Melbourne Water: ASPEN and supervisory control and data acquisition (SCADA) databases.

Data provider

Melbourne Water.

Method

This item represents the total metered volume of recycled water used on-site for wastewater treatment processes at Melbourne Water’s wastewater treatment plants.

On-site recycled water is measured by Melbourne Water at the Eastern and Western treatment plants, using ultrasonic level transmitters.

Recycled water used on-site or in-process	Volume (ML)
U34.a Volume of recycled water used on-site at Western Treatment Plant	24,337
U34.b Volume of recycled water used on-site in-process at Eastern Treatment Plant	14,179
Total volume of recycled water used on-site	38,516

Uncertainty

Ultrasonic level transmitters are used to measure flows and are assumed to have an accuracy of +/–5 to +/–10%.

Assumptions, approximations and caveats/limitations

The Western Treatment Plant logs data daily and reports quarterly. The Eastern Treatment Plant logs data daily and reports monthly. Thus, metering periods align with the reporting period.

National Water Account 2010