Melbourne
19.4 Delivery to urban water system users

The volume presented in the water accounting statements (343,166 ML) represents delivery of water from retail and rural water authorities to their end users and to the irrigation schemes in the Melbourne region during the 2010–11 year.

Delivery to urban system users

Water authority	Type of water	Purpose	Volume (ML)
City West Water	Potable	Residential	46,318
		Commercial, industrial, municipal	37,804
	Recycled	Commercial, industrial, municipal	137
	Subtotal for City West Water		84,259
Melbourne Water	Recycled	Recycled water supply to Eastern Irrigation Scheme	1,666
		Conservation flows to wetlands within the Western Treatment Plant	18,723
	Subtotal for Melbourne Water		20,389
South East Water	Potable	Residential	81,650
		Commercial, industrial, municipal	27,195
	Non-potable	Residential, commercial, industrial, municipal	62
		Other	4
	Recycled	Residential	102
		Commercial, industrial, municipal	446
		Agricultural/individual irrigation	793
	Subtotal for South East Water		110,252
Southern Rural Water	Potable	Bacchus Marsh Irrigation District	45
	Recycled	Werribee Irrigation District	1,746
		Werribee Tourist Precinct	43
	Subtotal for Southern Rural Water		1,834
Western Water	Potable	Residential	7,594
		Commercial, industrial, municipal	1,447
	Recycled	Residential	5
		Commercial, industrial, municipal	12
		Agricultural/individual irrigation	2,743
	Subtotal for Western Water		11,801
Yarra Valley Water	Potable	Residential	89,661
		Commercial, industrial, municipal	24,100
	Non-potable	Residential	48
		Commercial, industrial, municipal	250
	Recycled	Residential	61
		Commercial, industrial, municipal	310
		Agricultural/individual irrigation	201
	Subtotal for Yarra Valley Water		114,631
Total			343,166

City West Water Gentrack billing system.

City West Water.

The volume of water delivered to end users from City West Water was the sum of the following components.

Potable water for residential use:

City West Water has over 320,000 meters; residential meters are read on a quarterly basis. Generally, non-residential customers consuming greater than 10 ML per annum are read monthly and those that consume less than 10 ML are read quarterly.

Volumes are derived from monthly and quarterly meter readings, which are used to bill non-residential and residential customers. City West Water's Gentrack billing system collates all meter readings from residential and non-residential customers. Volumes are applicable to the 2010–11 year.

Recycled water supplied for commercial, industrial and municipal use

This item represents the metered volume of recycled water purchased and received from Melbourne Water's Western Treatment Plant. Data is collected from flow meters and an electronic logger capture system.

Volumes are only applicable to water use within the City West Water service area inside the Melbourne region. There was no residential supply to Little River during the 2010–11 year.

Uncertainty of this item is +/– 5% according to meter specifications

Melbourne Water.

Melbourne Water.

Recycled water supplied to other water authorities and private organisations is measured with magnetic flow meters at the interface of Melbourne Water and the receiving authority. The Western Treatment Plant logs data daily and reports quarterly. The Eastern Treatment Plant logs data daily and reports monthly.

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

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

Nil.

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

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

South East Water HiAffinity database.

South East Water.

The volume of water delivered to end users from South East Water was the sum of the following components.

Potable water for residential, commercial, industrial and municipal use
The item represents the quarterly metered volume of potable water supplied for residential use. Most of the meters were located at property boundaries.

Non-potable water for residential, commercial, industrial and municipal use
The item represents the quarterly (some large users are monthly) metered volume of potable water supplied for commercial, industrial and municipal use. Most of the meters were located at property boundaries. This value is the total non-residential water use

Recycled water for residential, commercial, industrial, municipal, agricultural and individual irrigation
This item represents the quarterly metered volume of recycled water supplied for residential, commercial, industrial and municipal use.

Assumes meters and readings are accurate.

Data reported from 01 July 2010 – 30 June 2011 are based on the four quarterly readings on each property. The water year for properties read early in the cycle starts in April and are billed in July. Later readings in the cycle have a meter year that starts in June and is billed in September.

Some quarterly readings are estimated (due to issues such as meter inaccessibility) and will be adjusted in following periods.

Potable and non-potable water for residential, commercial, industrial and municipal use

Water Industry Regulatory Audits 2011,  October 2011 (WIRA 2011)indicated that reliability and accuracy for metered volume of potable water delivered is +/– 5% (i.e. Grade 2).

Recycled water for residential, commercial, industrial, municipal, agricultural and individual irrigation:
+/– 5% in accordance with the WIRA 2011 independent annual audit report.

Melbourne Water Waterworks database, Western Water IT database.

Melbourne Water and Western Water.

The volume of water delivered to end users from Southern Rural Water was the sum of the following components:

Potable water supplied to Bacchus Marsh Irrigation District
The item represents the total metered volume of potable water supplied to Southern Rural Water via Western Water's infrastructure.

Recycled water supplied for Werribee Irrigation District and Werribee Tourist Precinct

This item represents the total metered volume of recycled water supplied from Melbourne Water's Western Treatment Plant to Southern Rural Water. All water that is recycled for supply to other water authorities from Melbourne Water is measured with magnetic flow meters at the interface of Melbourne Water and the receiving authority. The Western Treatment Plant logs data daily and reports quarterly.

Nil.

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.

Western Water information technology database water usage spreadsheet.

Western Water.

The volume of water delivered to end users from Western Water was the sum of the following components.

Potable water for residential, commercial, industrial and municipal use:
This item represents the total, monthly and four-monthly metered volume of potable water supplied for residential use, excluding potable water supplied to Woodend.

Non-potable water for residential, commercial, industrial and municipal use

This item represents the total metered volume of potable water supplied for commercial, industrial and municipal use, but excludes potable water supplied to Woodend. Meters are located at the owners' individual properties. Meters are read every four months.

Recycled water for residential use
This item represents the total metered volume of recycled water supplied for residential use. The meter is located at the outflow from the class tank. All non-residential volumes are subtracted, leaving a residential use total. Meters are read monthly.

Recycled water for commercial, industrial, municipal, agricultural and individual irrigation

This item represents the total metered volume of recycled water supplied for commercial, industrial, municipal uses and agricultural use. Meters are located at customer properties and are read monthly.

Nil.

+/– 5% in accordance with Summary Audit Report – October 2010 (Essential Services Commission 2010) .

Yarra Valley Water quarterly billing database

Yarra Valley Water

The volume of water delivered to end users from Yarra Valley Water was the sum of the following components:

Potable water for residential, commercial, industrial and municipal use

The item represents the metered volume of potable water supplied for residential, commercial, industrial and municipal use.

Customer usage is calculated as the difference between total water received and estimated non-revenue water volume, and is then divided into residential and non-residential components in the same ratio as the customer-billed volumes.

Non-potable water for residential, commercial, industrial and municipal use
The item represents the quarterly (some large users are monthly) metered volume of potable water supplied for commercial, industrial and municipal use. Most of the meters were located at property boundaries. This value is the total non-residential water use.

Recycled water for residential, commercial, industrial, municipal, agricultural and individual irrigation:

This item represents the metered volume of recycled water supplied to the Aurora recycled water development scheme for residential use as well as some small volumes from Brushy Creek and Wallan treatment plants. The volume is derived from the billed volume of recycled water through third pipe schemes to residential customers.

• customer usage in the reporting period is the difference between the total water received and the estimated level of nonrevenue water
• residential and non residential usage volumes are in the same proportion as billed and metered volumes
•  billed volumes over the four quarters provide an adequate estimate of water used in the reporting period.

 

+/–5%.

This line item was not reported in the 2010 Account. In the 2010 Account, the urban users were included in the region's definition. In the 2011 Account, the urban users were excluded from the region's definition. This change was made to allow reporting, in the water accounting statements, on urban water use (as a water asset decrease) and wastewater collection (as a water asset increase), as both were considered useful information to the National Water Account users.

This change was considered material and increased the accuracy and comparability of the information provided to the users of the National Water Account.The comparative year volume is 322,660 ML.