Indicator: IW-14 Volume of sewage discharge to surface waters by treatment category (primary, secondary, tertiary)


Water discharge and reuse from water utility STPs in Australia, 1996-9 and 2001-02
1996-9 2001-2
State / Territory Effluent, GL/yr Recycled, GL/yr % Effluent, GL/yr Recycled, GL/yr %
Qld 328 38 11.6 339 38 11.2
NSW 548 40.1 7.3 694 61.5 8.9
ACT 31 0.25 0.8 30 1.7 5.6
Vic 367 16.9 4.6 448 30.1 6.7
Tas 43 1 2.3 65 6.2 9.5
SA 91 9 9.9 101 15.2 15.1
WA 109 5.5 6.1 126 12.7 10
NT 21 1 4.8 21 1.1 5.2
Aust. 1 538 112.9 7.3 1 824 166.5 9.1

Source: Radcliffe, J 2003, An overview of water recycling in Australia - Results from the recent ATSE study, CD-Rom, Water Recycling in Australia, 2nd National Conference, 1-3 September 2003, Brisbane, Australian Water Association, Sydney,

Cited in Source: Australian Academy of Technological Sciences and Engineering 2004, Water Recycling in Australia, ATSE, Parkville, Victoria, viewed 4 Oct 2005,, Table 2, p. 7

Effluent discharge to inland waters in Australia is usually from smaller inland communities, with a few exceptions such as Canberra, and other regional cities and larger towns. Most of the effluent recorded in the table above is discharged into the ocean or tidal watercourse.

In Australia (with very few exceptions), discharge to inland waters occurs after a minimum of secondary treatment. Commonly, disinfection is a requirement. There is an increasing need for the removal of nitrogen and phosphorus, particularly for the large discharges, or where the effluent constitutes a significant proportion of total stream flow. Nutrient removal is desirable for discharges to the longer inland rivers, especially where there are other nutrient inputs from agriculture.

Source: National Pollutant Inventory 1999, Emission Estimation Technique Manual for Sewage and Wastewater Treatment, Environment Australia, Canberra, viewed 4 Oct 2005,

Volume of effluent discharged to non-tidal waterbodies, Qld, 2001
Treatment Volume (ML/yr)
Biological nutrient reduction 710
Partial nutrient reduction 9 058
Secondary 11 453
Low cost secondary 1 796
Not stated 336
Total 23 353

Source: Environmental Protection Agency - Queensland (unpubl.) 2001, Volume of effluent discharged to non-tidal waterbodies, Qld, 2001, Dr Laurence Knight Environmental Reporting Unit Environmental Protection Agency PO Box 15155, CITY EAST, Qld, 4002 Ph 07 3227 8956, Fax 07 3220 3542 Email

What the data mean

Effluent discharge has increased slightly between the 1996-9 and 2001-02. Capital cites and coastal towns account for most of the effluent.

Issues for which this is an indicator and why

Inland Waters - Habitat scale influences - Water Quality (for surface and groundwater) - Nutrients 

Discharge from sewage treatment plants can contribute to nutrient enrichment in rivers and streams. High nutrient levels, combined with the increased periods of low flow due to river regulation and water extraction, have caused blue-green algal blooms to become a persistent problem in some dams, wetlands and lakes.

Other indicators for this issue:

Inland Waters - Habitat scale influences - Water Quality (for surface and groundwater) - Other pollutants 

Wastewater from sewage treatment plants can contain pollutants in high enough concentrations to cause ecological harm.

Sewage treatment plant discharges are also a major source of pathogens. Most sewage treatment plants disinfect their discharges to kill pathogens, but the effectiveness and reliability of disinfection varies with flow and age of the sewage treatment plant.

Quantity of sewage discharge to inland waters is a direct measure of these pressures.

Other indicators for this issue:

Human Settlements - Pressures created by human settlements on the environment - Waste 

Sewage treatment plant discharges from cities and towns are a major source of pollutants and nutrients in aquatic environments, which, if in high enough concentrations, can cause ecological harm. Quantity of sewage discharge to inland waters is a direct measure of this pressure of human settlements on inland waters.

Other indicators for this issue:

Further Information