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Summary of water distribution system

Figure 1 and tables 1–5 summarise the water distribution for South East 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 South East 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 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 collected is treated by Melbourne Water.
Note 3: Total water usage (116,042 ML) is taken as: (1) volume of water supplied via the urban water supply system (excluding nonrevenue water) (112,661 ML) plus (2) volume of water supplied via the recycled water supply system (3,381 ML).
Note 4: (1) Volume of wastewater treated by South East Water (11,487 ML); (2) volume of effluent discharge (8,852 ML) + volume of recycled water produced (2,904 ML) = 11,756 ML. The difference between (1) and (2) is likely due to differences in metering accuracies.
Note 5: Volume of recycled water produced (2,904 ML) = recycled water used on-site (928 ML) + recycled water for supplies (1,976 ML).
Note 6: Recycled water for supplies (1,976) + recycled water received from other organisations (1,405 ML) = recycled water supplied (3,381 ML).

 

Table 1: Sources of water supplied to the South East Water urban supply area

Sources of water		Volume (ML)	Note
Delivered via the water supply system (connected areas)	Water sourced from external entity (Melbourne Water)	125,325	SEW_U4+ SEW_U5
	Water sourced from surface water	0
	Water sourced from groundwater	21	SEW_U2
	Water sourced from desalination	0
	Water sourced from recycle	See Table 4
	Total water sourced to supply connected areas	125,346
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)		125,346

* Data on directly abstracted water are likely to be unavailable or incomplete, and therefore not included in the scope of the National Water Account 2010.

 

Table 2: Water usage via urban water supply system

Item	Water usage	Volume (ML)	Note
1	Residential – potable water	83,818	SEW_U9
2	Residential – non-potable water	(included in item 4)
3	Commercial, industrial, municipal – potable water	28,741	SEW_U10
4	Commercial, industrial, municipal – non-potable water*	102	SEW_U14
5	Other including agricultural – potable water	0
6	Agricultural – non potable water	0
7	Environment – potable water	0
8	Environment – non potable water	0
	Total	112,661	Items 1 + 3 + 4

* Represents the total supply of non-potable water for residential, commercial, industrial and municipal use.

 

Table 3: Wastewater

Item	Wastewater collected and treated	Volume (ML)	Note
1	Wastewater collected by South East Water	103,287	SEW_U19a
2	Wastewater received from other water authorities in the region	0
3	Wastewater delivered to Melbourne Water	91,800	SEW_U21
4	Subtotal wastewater treated	11,487	Item 1 – 3, SEW_U19b
5	Wastewater treated for recycling	2,904	SEW_U30
6	Wastewater (treated) discharged to surface water	792	SEW_U22
7	Wastewater (treated) discharged to ocean	8,060	SEW_U23
8	Subtotal treated wastewater discharged	8,852	Items 6 + 7

 

Table 4: Recycled water

Item	Recycled water produced and supplied	Volume (ML)	Note
1	Total recycled water produced	2,904	SEW_U30
2	Total recycled water received from other organisations within the region	1,405	SEW_U28
3	Recycled water use on-site in-process	928	SEW_U34
4	Recycled water supplied to residential	117	SEW_U31
5	Recycled water supplied to commercial, industrial, municipal	1,659	SEW_U32
6	Recycled water supplied to agricultural	1,605	SEW_U33
7	Recycled water supplied to environment	0
8	Recycled water supplied to artificial recharge	0
9	Total recycled water supplied	3,381	Items 4 + 5 + 6

 

Table 5: Urban water supply system water losses

Losses	Volume (ML)	Disclosure
Losses from potable, non-potable water supplies*	12,685	SEW_U11
Losses from recycled water supplies	0
Total water losses	12,685

*Nonrevenue water including losses due to background leakage (SEW_U15) and pipe bursts (SEW_U17)

 

U2 Volume of water taken from groundwater for water supply

SEW_U2: 21 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the smart meter (real-time) metered volume of water extracted from the Lang Lang bore.

 

Water taken from groundwater	Volume (ML)
Groundwater extracted from Lang Lang bore	21
Total	21

 

Uncertainty

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

Assumptions, approximations and caveats/limitations

Assumes the meters and readings are accurate.

 

U4 Volume of potable water imported or received from other water authorities within the region

SEW_U4: 125,244 ML

Data source

Melbourne Water: database.

Data provider

Melbourne Water.

Method

This item represents the weekly metered volume of bulk water supplied by Melbourne Water as contained in weekly invoices. The meter network and locations are contained in a bulk supply agreement with South East Water.

Uncertainty

+/–5% in accordance with an independent, annual audit. The Summary Audit Report – Regulatory Audit of AGL Energy Limited, October 2010 (ESC 2010) indicated that reliability and accuracy for metered volume of potable water delivered as +/–5% (i.e. Grade 2).

Assumptions, approximations and caveats/limitations

Assumes any errors in invoices are corrected in the next invoice. Data reported from 01 July 2009 – 30 June 2010.

 

U5 Volume of non-potable water imported or received from other water authorities within the region

SEW_U5: 81 ML
Supporting information as supplied under U14 Component 1.

Assumptions, approximations and caveats/limitations

As above.

 

U9 Volume of potable water supplied for residential use

SEW_U9: 83,818 ML

Data source

South East Water: HiAffinity database (South East Water billing system).

Data provider

South East Water.

Method

The item represents the quarterly metered volume of potable water supplied for residential use. Most of the meters were located at property boundaries.

Uncertainty

+/–5% in accordance with an independent, annual audit. The Summary Audit Report – Regulatory Audit of AGL Energy Limited, October 2010 (ESC 2010) indicated that reliability and accuracy for metered volume of potable water delivered is +/–5% (i.e. Grade 2).

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

Data reported from 01 July 2009 – 30 June 2010 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), and the later reads in the cycle have a meter year that starts in June and is billed in September.

Some quarterly readings are estimated (due to issues including inability to access meter) but will be adjusted in following periods.

 

U10 Volume of potable water supplied for commercial, industrial and municipal uses

SEW_U10: 28,741 ML

Data source

South East Water: HiAffinity database (South East Water billing system).

Data provider

South East Water.

Method

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.

Uncertainty

+/–5% in accordance with an independent, annual audit. The Summary Audit Report – Regulatory Audit of AGL Energy Limited, October 2010 (ESC 2010) indicated that reliability and accuracy for metered volume of potable water delivered is +/–5% (i.e. Grade 2).

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

U11 Volume of potable water supplied other than for residential, commercial, municipal and industrial uses

SEW_U11: 12,685 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the volume of nonrevenue water (bulk water supplied minus water sales).

Uncertainty

+/–5% in accordance with an independent, annual audit. The Summary Audit Report – Regulatory Audit of AGL Energy Limited, October 2010 (ESC 2010) indicated that reliability and accuracy for metered volume of potable water delivered is +/–5% (i.e. Grade 2).

Assumptions, approximations and caveats/limitations

Nonrevenue water includes infrastructure leakage, pipe burst, thefts and leak allowances.

 

U14 Volume of non-potable water supplied other than for residential, commercial, industrial and municipal uses

SEW_U14: 102 ML

Data source

South East Water: HiAffinity database (South East Water billing system).

Data provider

South East Water.

Method

This item represents the total volume of non-potable water supplied for customers (U12 + U13) for residential, commercial, industrial and municipal use, and includes the following components:

• Component (1): The quarterly metered volume of non-potable water provided from Bunyip River. The figure presented includes non-potable supply to all customers (U12 + U13), including residential, commercial, industrial and municipal use. Further breakdown is not available. Meters are generally located at property boundaries.
• Component (2): The smart meter (real-time) metered volume of water extracted from the Lang Lang bore (see U2).

 

Non-potable water supplied other than for residential, commercial, municipal and industrial use	Volume (ML)
Component (1) Supply of water taken from Bunyip River	81
Component (2) Supply of groundwater extracted from Lang Lang bore	21
Total	102

 

Uncertainty

Component (1): +/–5% in accordance with an independent, annual audit.
Component (2): +/–2% (meter type is an Elster R2000 100mm).

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

U15 Background leakage from potable water supply system

SEW_15: 7,885 ML

Data source

South East Water: various internal sources and the database.

Data provider

South East Water.

Method

This item represents the estimated leakage component of nonrevenue water (based on the Water Services Association of Australia Benchloss software).

Uncertainty

+/–10% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

As appropriate to the standard method.

 

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

SEW_17: 1,156 ML

Data source

South East Water: various internal sources and the database.

Data provider

South East Water.

Method

This item represents the estimated pipe bursts component of nonrevenue water. The volume is estimated using a spreadsheet calculator based on multiple inputs in line with Infrastructure Leakage Index (ILI) standards.

The International Water Association has developed the ILI indicator to better represent the performance of water supply systems and their management in terms of leakage. The ILI is defined as the ratio of Current Annual Real Losses (CARL) to Unavoidable Annual Real Losses (UARL). CARL are determined from a conventional water balance undertaken on an annual basis. The UARL is a formula that accounts for the number of connections, the length of water mains and the average system operating pressure.

Uncertainty

+/–10% in accordance with and independent, annual audit. The Summary Audit Report – Regulatory Audit of AGL Energy Limited, October 2010 (ESC 2010) indicated that reliability and accuracy for the calculation of losses is +/–10% (i.e. Grade 3).

Assumptions, approximations and caveats/limitations

As appropriate to the standard method.

 

U19a Volume of wastewater collected

SEW_U19a: 103,287 ML

Data source

South East Water: database.

Data provider

South East Water and Melbourne Water.

Sewage from South East Water customers is collected in its sewerage system and then transferred to Melbourne Water for further transport, treatment and disposal, or to South East Water for further transport, treatment and disposal. The data have been sourced from both providers as outlined in the ‘Method’ section.

Method

Meter readings. This item represents the daily metered volume of wastewater collected and treated at South East Water’s sewage treatment plants, plus the weekly invoice volume of wastewater exported to Melbourne Water’s Eastern and Western treatment plants.

Melbourne Water has a suite of bulk meters and formulas in order to attribute volumes to the three retailers. The meter network and locations are contained in a bulk supply agreement with South East Water.

 

Wastewater collected	Volume (ML)
Wastewater collected and treated at South East Water’s sewage treatment plants	11,487
Wastewater collected and exported to Melbourne Water’s Western Treatment Plant	24,900
Wastewater collected and exported to Melbourne Water’s Eastern Treatment Plant	66,900
Total	103,287

Uncertainty

+/–5% in accordance with and independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate. The total volume (103,287 ML) reflects the volume of wastewater received from South East Water customers. Collection for disposal has been allocated to South East Water and Melbourne Water.

 

U19b Volume of wastewater treated

SEW_U19b: 11,487 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the daily metered volume of wastewater treated at South East Water sewage treatment plants.

 

Sewage treatment plant	Volume (ML)
Blind Bight	168
Hastings (Somers)	1,558
Koo Wee Rup	132
Lang Lang	59
Longwarry	182
Mornington (Mount Martha)	4,327
Pakenham (Deep Creek)	2,008
Rosebud (Boneo)	3,054
Total	11,487

 

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

U19a indicates the volume collected by South East Water (103,287 GL) and U19b indicates the volume treated by South East Water (11,487 GL).

 

U21 Volume of wastewater exported or delivered to other water authorities within the region

SEW_U21: 91,800 ML

Data source

Databases.

Data provider

South East Water and Melbourne Water.

Method

Meter readings. This item represents the weekly invoice volume of wastewater exported to Melbourne Water’s Eastern and Western treatment plants.

Melbourne Water has a suite of bulk meters and formulae in order to attribute volumes to the three retailers. The meter network and locations are contained in a bulk supply agreement with South East Water.

 

Location wastewater was exported to	Volume (ML)
Western Treatment Plant (Melbourne Water)	24,900
Eastern Treatment Plant (Melbourne Water)	66,900
Total wastewater delivered to Melbourne Water	91,800

 

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

U22 Volume of (treated) wastewater discharged to surface water

SEW_U22: 792 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the daily metered volume of treated wastewater discharged to Deep Creek and Yallock Creek.

 

 

Wastewater discharged to surface water	Volume (ML)
Pakenham Sewage Treatment Plant to Deep Creek	792
Koo Wee Rup Sewage Treatment Plant Yallock Creek – Koo Wee Rup	0
Total discharge	792

 

 

Uncertainty

+/–5% in accordance with and independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

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

SEW_U23: 8,060 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the daily metered volume of treated wastewater discharged to the sea from the South East Outfall.

U23 table:

 

Discharge to sea from South East Outfall	Volume (ML)
Hastings (Somers) Sewage Treatment Plant	1,154
Mornington (Mount Martha) Sewage Treatment Plant	4,273
Rosebud (Boneo) Sewage Treatment Plant	2,633
Total	8,060

 

 

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.
This item only refers to wastewater volumes directly managed by South East Water (see item U19b).

 

U28 Volume of recycled water imported or received from other organizations within the region

SEW_U28: 1,405 ML

Data source

Spreadsheet.

Data provider

South East Water.

Method

This item represents the quarterly metered volume of recycled water purchased from Melbourne Water’s South East Outfall and TopAq Eastern Irrigation Scheme, and received from Inkerman Greywater Treatment Plant.

 

Recycled water received from other organisations within the region	Volume (ML)
U28.a: Recycled water purchased from Melbourne Water’s South Eastern Outfall	1,135
U28.b: Recycled water purchased from TopAq Eastern Irrigation Scheme	268
U28.C: Recycled water received from Inkerman Greywater Treatment Plant	2
Total	1,405

 

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

The TopAq Eastern Irrigation Scheme meter-reading cycle does not align with the 01 July 2009 – 30 June 2010 reporting year; however, it does cover a 12-month period that is consistently applied each year.

 

U30 Volume of recycled water produced from wastewater

SEW_U30: 2,904 ML

Data source

Spreadsheet.

Data provider

South East Water.

Method

This item represents the monthly metered volume of recycled water produced at South East Water’s sewage treatment plants.

 

Recycled water produced	Volume (ML)
South East Water’s sewage treatment plants	2,904
Total	2,904

 

 

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

U31 Volume of recycled water supplied for residential use

SEW_U31: 117 ML

Data source

South East Water: HiAffinity database (South East Water billing system).

Data provider

South East Water.

Method

This item represents the quarterly metered volume of recycled water supplied for residential use. br>

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

U32 Volume of recycled water supplied for commercial, industrial and municipal uses

SEW_U32: 1,659 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the quarterly or monthly metered volume of recycled water supplied for commercial, industrial and municipal use.

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

U33 Volume of recycled water supplied for agriculture

SEW_U33: 1,605 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the quarterly metered volume of recycled water supplied for agricultural use.

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

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

SEW_U34: 928 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the daily metered volume of recycled water used for in-process water at South East Water’s sewage treatment plants.

 

Sewage treatment plant	Volume (ML)
Blind Bight	50
Hastings (Somers)	8
Koo Wee Rup	0
Lang Lang	0
Longwarry	0
Mornington (Mount Martha)	808
Pakenham (Deep Creek)	32
Rosebud (Boneo)	29
Total	928

 

Uncertainty

+/–5% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumes meters and readings are accurate.

 

U35 Volume of nonrevenue water (relevant to recycled water supplies)

SEW_U35: 0 ML

Data source

South East Water: database.

Data provider

South East Water.

Method

This item represents the volume of nonrevenue water with respect to the supply of recycled water. The nonrevenue component of recycled water supply is calculated as the difference between the volume of recycled water produced and/or purchased, and the volume of recycled water supplied to customers.

Uncertainty

+/–10% in accordance with an independent, annual audit.

Assumptions, approximations and caveats/limitations

Assumptions are based on mass-balance calculation formulas.