Melbourne
19.7 Wastewater discharge outside of region

The volume presented in the water accounting statements (304,745 ML) represents the volume of wastewater discharged from water authorities in the Melbourne region to Port Phillip Bay and Bass Strait.

The following table shows the breakdown of wastewater discharged from each treatment plant by organisations in the Melbourne region during the 2010–11 year.

Wastewater discharged outside of region

Organisation	Discharge location	Volume (ML)
Melbourne Water	Western Treatment Plant discharge to Port Phillip Bay	146,632
	Eastern Treatment Plant discharge to Bass Strait	142,419
	Melbourne Water subtotal	289,051
City West Water	Altona Sewage Treatment Plant discharge to Port Phillip Bay	5,675
	City West Water subtotal	5,675
South East Water	Somers Sewage Treatment Plant discharge to South East Outfall	1,915
	Mt Martha Sewage Treatment Plant discharge to South East Outfall	4,861
	Boneo Sewage Treatment Plant discharge to South East Outfall	3,243
	South East Water subtotal	10,019
Total		304,745

City West Water supervisory control and data acquisition (SCADA) database.

City West Water.

This item represents the metered volume of treated wastewater discharged from the Altona Wastewater Treatment Plant into Port Phillip Bay. Meters are located at the Altona plant and are read on a daily basis. The line item is calculated by deducting the metered volume of water used in-process within the treatment plant from the metered wastewater discharge value.

Nil.

Uncertainty is +/– 5%

Melbourne Water: derived from metered data.

Melbourne Water.

This item represents the volume of wastewater discharged to sea (including Port Phillip Bay) from Melbourne Water's Western Treatment Plant and Eastern Treatment Plant.

The volume is determined using a mass-balance calculation of all wastewater collected, treated, stored and recycled.

Nil.

The uncertainty estimate was not quantified.

South East Water database.

South East Water.

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

 

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

 

Uncertainty is +/– 5% in accordance with the Water Industry Regulatory Audits 2011 independent annual audit report.

 

This item corresponds to line item 20.4.2 Wastewater discharge out of region reported in the 2010 Account. There was no change to the volume reported in the 2010 Account. The comparative year volume is 208,934 ML.