Indicator: CO-51 Quantity of sewerage and ballast water dumped by shipping


Ballast water

AQIS has estimated that the tonnage of ballast water from overseas locations that is discharged inside Australia's territorial sea each year is between 150 and 200 million tonnes.

This is based on an estimate that most bulk carriers that come to Australia arrive with no cargo on board but with all ballast tanks filled to capacity. A bulk carrier, in the absence of cargo, carries about one third of its cargo payload in ballast water.

On this basis, since Australia exports between 500 and 600 million tonnes of dry bulk commodities (coal, iron ore etc) each year by sea, Australian waters would receive about 150 - 200 million tonnes of foreign ballast water in a year.

All ballast water from outside Australia's territorial sea must be managed to make it low-risk to the marine environment before it may be discharged inside the territorial sea.

AQIS deems all salt water from ports (or coastal waters) outside Australia’s territorial sea to present a “high-risk” of introducing exotic marine species into Australia. The discharge of high-risk ballast water from ships is prohibited anywhere inside Australia’s territorial seas (12 nautical mile limit generally applies).

Ballast water of the following types is deemed by AQIS to be “low-risk”:

  • fresh water from any source;
  • ballast water that has been assessed as “low-risk” for discharge (at specified ports /locations on specified dates) by the ‘Ballast Water Decision Support System’ (BWDSS) - a computer application that can provide vessels with a risk assessment of their ballast water and deem it to be acceptable for discharge or otherwise;
  • ballast water that has been exchanged at an approved location (mid-ocean) by an approved method
  • ballast water taken up in mid-ocean
  • ballast water taken up inside Australia’s territorial seas.

Explicit written permission to discharge foreign ballast water in Australian waters must be obtained from AQIS prior to discharge. Every ship that arrives from overseas (with the exception of US Naval vessels which AQIS has no authority to inspect) is inspected, and inspectors verify, among other things, that, on every ship, ballast water has been managed in accordance with the law. Compliance with the mandatory ballast water management requirements is better than 99% for the approximately 12,500 annual voyages that arrive in Australia.

Source: Australian Quarantine and Inspection Service 2006, Australian ballast water requirements, viewed 25 May 2006,

  • Australian Ballast Water Management Requirements (PDF - 141 KB)

Please note, this information was correct at time of publication. All environmental indicator pages that underpin SoE 2006 are static and do not include subsequent data. For current information on ballast water arrangements, please refer to Australian Ballast Water Management Requirements


The discharge of sewage from ships is prohibited inside the territorial sea. If vessels need to discharge sewage, the material must be landed and disposed of under AQIS (or their authorised agents') supervision. Sewage may be landed with permission and pumped into a port's sewage mains.

What the data mean

The high level of compliance with the ballast water requirements means the risk of introduction into Australian waters of organisms from foreign ecosystems is low. However, even a low level of non-compliance can enable to introduction of potentially invasive species, as can discharge of water in the open sea, and discharge of water from elsewhere within Australia’s territorial waters

The law regarding sewage should mean that release of pollutants, nutrients or exotic organisms from this source do not occur. There may, however, be some level of non-compliance with these requirements which could introduce some level of risk from sewage discharges.

Data Limitations

The compliance data covers only waste and ballast dumping from international shipping in Australian waters. Ballast water taken up mid ocean could sometimes include organisms discharged in the ballast water of other vessels mid ocean. Records are not kept, nor international data compiled, on ballast and shipping waste dumped in international waters. Water moves, and water in the mid ocean will not necessarily remain in mid ocean, and nor will materials or organisms that are dumped in it.

Similarly, many marine animals are themselves highly mobile. Animals travelling from mid ocean have the potential to bring other organisms, materials, or the effects of them, into territorial waters. Materials and organisms dumped mid-ocean therefore do have some potential to impact on Australian marine ecosystems.

Moreover, AQIS does not control the exchange of ballast water from elsewhere within Australian waters. Yet Australia is a continent and its territorial waters comprise a wide range of diverse marine ecosystems. Species from one region may be as inappropriate, and as potentially damaging to local ecosystems in another region, as organisms from another continent.

Additionally, non-compliance with sewage discharge requirements is (by definition) difficult to monitor, and if discharged nutrients or exotic organisms did have any significant impact on marine species, they would be very difficult to trace.

Issues for which this is an indicator and why

Coasts and Oceans — Direct pressure of human activities on coasts and oceans - Direct pressure of shipping 

Because they are mobile and temporary human settlements, ships produce a similar range of wastes to that of any other human settlements, with an additional waste product in the form of ballast water. If these wastes are discharged into marine waters in sufficient quantities, or in particularly sensitive or vulnerable habitats, they can have impacts on marine species, poisoning some, entangling others (see also Indicator: Number of injuries to marine animals from marine debris), providing excess nutrients which can change the balance of species, causing blooms of some and declines of others, or introducing foreign organisms which have the potential to become invasive in a different ecosystem. Changes in estimated quantities of ballast water, sewage or other waste released into the ocean gives an idea of changes in the potential pressure from this source.

Other indicators for this issue:

Biodiversity — Pressures on biodiversity - Pressures on marine biodiversity: pressures of shipping 

Ballast water and sewage from shipping has the potential to place pressure on marine biodiversity. Changes in estimated quantities of ballast water, sewage or other waste released into the ocean gives an idea of changes in the potential pressure from this source.

Other indicators for this issue:

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

Insofar as ships are mobile human settlements, waste from shipping is one contributor of waste from human settlements.

Other indicators for this issue:

Further Information