An ocean outfall is a set of infrastructure (pumps, pipes & diffusers) that connects land-based wastewater treatment plants, stormwater and other waste that is discharged, treated or untreated into the marine environment.

Some ocean outfalls are discharged under the ocean's surface, some are visible and discharge directly from the sand.

Affectionately known as a “Poo Pipe” by some people.

An inland outfall is similar to an ocean outfall but discharges waste from inland waste water treatment plants into an inland body of water such as a creek, river or lake. 

Inland outfalls pose a significant risk to freshwater environments and recreational users of the discharge and of course to other communities, many of which draw their water downstream of another towns wastewater discharge.

Many Industries have permits to dispose of waste into the environment. Permits are issued by local (state based) Environmental Protection Authorities (EPA) via a fee based. The polluter pays a fee to enable it to “discharge” (ie. pollute) the environment. 

Industries include Gas (Fossil Fuel), Dredging, Aquaculture, Mining, Power stations, Sawmills and Desalination Plants.

In Australia and surrounding islands there are 192 coastal outfalls.

Clean Ocean Foundation developed in collaboration with the States and Northern Territory and supported by the National Environmental Science Programme - Marine Biodiversity Hub in association with the University of Tasmania (UTAS) a publicly accessible ocean outfall database.

The goal of National Outfall Database (NOD) is to facilitate cross-institutional data sharing among federal, state, local government and the community to integrate infrastructure planning and decision making of sewage effluent impacts on marine environment.

Clean Ocean Foundation is currently working on expanding the NOD to inland outfalls to provide a holistic view of outfall impacts on ocean and inland waters.

To learn more visit here: National Outfall Database.

Over 3,900 million litres per day.

Every year, Australian coastal outfalls dump enough wastewater into our oceans to fill the Sydney Harbour nearly three times.

Wastewater is a general term of water that can be produced from effluent, homes, businesses, industry and others. Generally the quality of the water discharged is poorly treated and contains pollutants including forever chemicals (PFAS) , microplastics, heavy metals and pharmaceuticals, nutrients and other chemicals that are known to cause harmful impacts to the marine environment.

During the wastewater treatment process, there are two outputs,
wastewater released in to the ocean via outfalls and sludge.


Sludge contains solids that have been collected at the start of the
treatment process, which contains organic matter (human waste, food),
inorganic materials (medicines), contaminants, microplastics, PFAS.
Sludge does not undergo any further treatment.


The most common end use of sludge in Australia is the application to
agricultural land, landscaping and soil amendment. Meaning, all of the
untreated matter collected during the waste water treatment process is
being transferred on to our landscape - spreading the impact of these
contaminants.

Main contaminants are PFAS (and other Forever Chemicals), Microplastics, Nutrients (nitrogen and phosphorus), Heavy Metals, Pharmaceuticals, chemicals and pathogens.

Wastewater pollution poses several risks to the marine environment, impacting ecosystems, biodiversity, and the health of both wildlife and humans.

• Eutrophication

  Wastewater often contains high levels of nutrients like nitrogen and phosphorus, which lead to algal blooms. These blooms deplete oxygen in the water, causing dead zones where marine life cannot survive. This disrupts food chains and reduces biodiversity'.

• Toxic Chemicals and Microplastics

  Wastewater carries harmful substances such as heavy metals, pesticides, pharmaceuticals, and microplastics into the ocean. These contaminants accumulate in marine organisms, affecting their health and reproductive systems. For example, fish exposed to wastewater can suffer from physiological changes, such as developing both male and female reproductive organs (intersex conditions), which harms populations.

• Pathogens and Public Health Risks

  Untreated wastewater can introduce harmful bacteria, viruses, and parasites into the marine environment, which can spread diseases to humans through contaminated seafood or direct contact with polluted water.

  This can affect industries like fisheries and tourism.

• Ocean Acidification and Climate Change

  Wastewater pollution can exacerbate ocean acidification by increasing the concentration of carbon-rich compounds in the water, which lowers the pH. Acidification weakens marine organisms like coral reefs and shellfish, further threatening marine biodiversity.

• Damage to Coral Reefs Nutrient overload and the toxic substances in wastewater can damage sensitive marine ecosystems like coral reefs, which are critical for marine biodiversity.

  Coral reefs depend on clear, nutrient-poor water, and excess nutrients encourage algae growth, which smothers coral reefs.

Addressing these risks requires better wastewater treatment infrastructure, stricter regulations on industrial discharge, and initiatives to reduce nutrient and chemical pollution.

An algal bloom occurs when there is an overgrowth of algae in a body of water, driven primarily by an excess of nutrients like nitrogen and phosphorus. These nutrients can come from sources such as agricultural runoff, untreated wastewater, and industrial discharge. When nutrient levels rise significantly, algae—particularly phytoplankton—begin to reproduce rapidly, leading to dense concentrations of algal cells. This process is called eutrophication.

Here’s how it unfolds:

Nutrient Input: Excessive nutrients, especially nitrogen and phosphorus, enter water bodies from wastewater, fertilisers, or sewage discharges.

Algae Growth: The increased nutrients stimulate the rapid reproduction of algae, causing a bloom.

Oxygen Depletion: As the algae die and decompose, the process consumes large amounts of oxygen in the water, leading to hypoxic (low oxygen) or anoxic (no oxygen) conditions, creating dead zones.

Light Blockage: Algal blooms block sunlight from reaching underwater plants, disrupting photosynthesis and harming aquatic ecosystems.

Toxins: Some types of algae, particularly cyanobacteria (blue-green algae), produce toxins harmful to marine life, wildlife, and humans.

These blooms can have serious consequences for marine environments, including fish kills, the disruption of aquatic food chains, and contamination of drinking water sources.

A red tide is a harmful red algal bloom which can be observed by a red discolouration of the ocean’s surface.

The toxins produced by this bloom are capable of killing fish and other marine animals, and as they become airborne, can have respiratory effects on people nearby.

The best way to reduce the occurrence of red tides is to upgrade water treatment plants to quaternary treatment.

Waste categorisation hierarchy (Whilst Australia's Environmental Protection Authorities are state based, the general waste categorisation hierarchy in managing waste is to; 1. Avoid, 2. Reuse, 3. Recycle, 4. Recover 5. Treat, 6. Contain, 7. Dispose.

Disposal (current version of ocean outfall) is the worst option chosen by the authorities for the least capital expenditure.

• Quaternary wastewater treatment is an advanced stage of wastewater purification, occurring after primary, secondary, and tertiary treatments. It involves the removal of micro-pollutants and contaminants that remain in the water after previous treatments, such as pharmaceuticals, heavy metals, pesticides, hormones, and microplastics.

  Quaternary treatment often employs cutting-edge technologies such as membrane filtration, adsorption with activated carbon, advanced oxidation processes (AOPs), and ion exchange to target these microscopic or chemically resistant substances.

  These treatments help eliminate pollutants that are resistant to biodegradation, safeguarding ecosystems and improving water reuse potential.

• Tertiary wastewater treatment is the third and most advanced stage of wastewater purification, following primary (physical) and secondary (biological) treatments. Its goal is to remove contaminants that were not eliminated during the earlier stages, particularly nutrients like nitrogen and phosphorus, as well as pathogens, fine particles, and residual organic matter.

  This stage helps improve water quality to meet stringent environmental standards for discharge or reuse.

• Secondary wastewater treatment is the second stage of the wastewater purification process, focusing on the biological removal of dissolved organic matter that was not filtered out during primary treatment.

  This stage primarily uses microorganisms to break down and consume organic pollutants in the wastewater, converting them into simpler compounds like XXX.

  The goal of secondary treatment is to significantly reduce biochemical oxygen demand (BOD) and remove suspended solids, making the effluent suitable for further treatment (tertiary) or for discharge into water bodies, depending on regulatory standards.

• Primary wastewater treatment is the first stage in the wastewater treatment process.

  It focuses on the physical removal of solid materials from the wastewater through sedimentation, screening, and other mechanical processes.

  The goal is to separate suspended solids, floating debris, and organic matter from the liquid phase before further biological or chemical treatments.

The waste produced (sludge) through the treatment process includes nappies, menstrual products, faeces, dead animals is currently stored as authorities do not know a solution to treat.

Popular opinion is to put the waste on to the land however this will leach back in to waterways and spread the impact further.I’ve added below.

Sludge from wastewater treatment, also known as sewage sludge, poses several challenges due to its composition and the complexities involved in its disposal or reuse.

Key problems include:

Toxic Contaminants

Sludge can contain harmful substances such as heavy metals, pesticides, pharmaceuticals, microplastics, and industrial chemicals.

These contaminants can be hazardous to the environment and public health if not properly treated. When sludge is applied as fertiliser or disposed of in landfills, these toxins can leach into the soil, water bodies, and eventually enter the food chain.

Pathogens and Public Health Risks

Sewage sludge contains a high concentration of pathogens such as bacteria, viruses, and parasites that can pose serious health risks to humans and animals.

If not adequately treated, the use of sludge in agriculture can spread diseases through contaminated food crops, water sources, or direct human contact.

Odour and Aesthetic Issues

Raw or improperly treated sludge emits strong, unpleasant odours due to the decomposition of organic matter, especially sulfur-containing compounds.

This can create significant nuisance issues for communities near treatment plants or sludge disposal sites.

Disposal and Storage

Handling large volumes of sludge is expensive and space consuming.

Traditional disposal methods such as landfilling and incineration present environmental risks:

Landfilling

Space constraints and concerns about groundwater contamination.

Incineration

High costs and air pollution from toxic emissions during burning.

Greenhouse Gas Emissions

Sludge that is improperly treated or disposed of can release methane and nitrous oxide, potent greenhouse gasses that contribute to climate change. Anaerobic digestion, while reducing these emissions, does not eliminate them entirely.

Nutrient Overload

When applied to land as fertiliser, sludge can contribute to nutrient pollution due to the excess nitrogen and phosphorus content.

This can lead to problems like eutrophication in nearby water bodies, which harms aquatic ecosystems.

Solving these issues involves advanced treatment technologies, safe disposal practices, and finding sustainable uses for sludge, such as energy recovery through anaerobic digestion or converting it to biochar for agricultural use.

We want all outfalls to discharge water that is safe for the environment and recreational users. For this to happen the wastewater must have been treated to the same level the European Union adopted in 2024.

This requires high level (quaternary) treatment to remove ALL micro-pollutants (including PFAS, other forever chemicals and microplastics) and nutrients from wastewater discharges and such an approach also maximises the potential for water reuse.

It is estimated that these upgrades would cost $15 billion but create an overall net benefit of $30 billion.

All comes down to money.