Sydney
19.7 Wastewater discharge outside of region

The wastewater system is one of three sub-components of Sydney's urban water system.  The three sub-components are the:

• Urban water supply system
• Wastewater system
• Recycled water system.

In the Sydney region, wastewater is collected from users by the Sydney Water Corporation, Shoalhaven City Council or Wingecarribee Shire Council (11.4) and transferred to wastewater treatment plants throughout the region.There is also some stormwater ingress reported by Wingecarribee Shire Council which is considered a wastewater inflow (11.7).

During the 2011–12 year, 7% of treated wastewater was recycled; 78% discharged to the sea (19.7); and the rest discharged to inland surface water (19.5). The following figure shows all the inflows and outflows associated with the wastewater system.

For more detail on a particular flow associated with the wastewater system, refer to the line item notes. Note that volumes annotated with a * indicate flows between sub-components and are not reported in the account. As such, these flows do not have an associated line item number.

The Sydney region's wastewater system using data retrieved from Sydney Water Corporation, Shoalhaven City Council and Wingecarribee Shire Council

This line item refers to the total metered volume of treated wastewater discharged to the sea or outside of the region. The discharge is from wastewater treatment plants and water recycling plants managed by Shoalhaven City Council and Sydney Water Corporation during the 2012 Account. The total volume is 472,073 ML (see the following table). 

Total wastewater discharged out of region

Managing authority	Plant type	Plant	Discharge volume to sea (ML)
Shoalhaven City Council	Wastewater treatment	Ulladulla	1,280
		Culburra	492
		St Georges Basin	857
		Callala	176
		Vincentia	421
		Sussex	519
		Bendalong	95
		Conjola	97
		Shoalhaven Heads1	183
Sydney Water Corporation	Wastewater treatment	Bellambi	1,018
		Port Kembla	888
		Warriewood	8,092
		Shellharbour	7,743
		Cronulla	23,288
		Bondi	50,234
		North Head	162,071
		Malabar	195,383
	Water recycling plant	Gerroa	0
		Bombo	1,847
		Wollongong	17,389
Total			472,073

1 Discharge occurs via sand dunes to the sea

New South Wales Office of Water, Water Supply and Sewerage Performance monitoring Report 2011–12

Shoalhaven City Council.

Outflow volumes from Shoalhaven Heads Wastewater Treatment Plant were measured using an Elster meter and a Parshall flume with a venturi flow meter.

Treated wastewater was discharged to the sea via sand dunes, which act as natural sand-bed filters.

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 5%.

Data managed and maintained in an internal data management system by Sydney Water Corporation's Service Delivery Division (Assurance and monitoring).

Sydney Water Corporation.

The number represents the total volume of treated wastewater discharged to the sea, based on flow meter readings from wastewater treatment plants and water recycling plants.

The flow of wastewater from the plants was measured using flow meters. These measured data are continually monitored and recorded using the Integrated Instrumentation Control Automation and Telemetry System (IICATS). The data are stored within an internal data management system. Adjustments are made to the data (if necessary) to correct any interruptions, errors and so on. Data have been extracted for the 2011–12 year from the data management system.

Nil.

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 2%.

An adjustment for the total discharge of wastewater outside of the region for 2011 is required as Shoalhaven Water sites Ulladulla, Culburra, Huskisson, St Georges Basin, Callala, Bendalong and Conjola were not included in the volume recorded for 2011. In 2011 these sites discharged 3,502ML outside of the region. This brings the total volume for the Sydney region for 2011 for this measure to a total of 431,504 ML. (This was previously recorded as 428,215ML).