The EPA is reviewing Sydney Water’s licences for its 23 sewage treatment systems across Greater Sydney and the Illawarra.

There are also a range of programs on the licences aimed at improving the environmental performance of Sydney Water’s sewage treatment systems over time.

We want to ensure the licences are fit for purpose, deliver an appropriate level of regulation and reflect the community’s views about the protection of human health and the environment.

In particular we would like your feedback on:

• the level of treatment required at Sydney Water’s sewage treatment plants and associated levels of environmental protection, wet weather discharges and the impacts of climate change
• monitoring requirements

Please note that pollution studies and reduction programs are targeted licence conditions aimed at addressing a specific issue e.g. wet weather overflow abatement. It should also be noted that this licence review does not relate to Sydney Water’s potable water supply activities.

Your views on the EPA’s regulation of Sydney Water’s sewage treatment systems are highly valued and will help inform the EPA’s ongoing improvements to Sydney Water’s licences.

Public consultation on the review of Sydney Water’s environment protection licences is now open until 5.00pm Thursday 12 June 2025.

Have your say on the 5-yearly review of Sydney Water’s environment protection licences.

You can provide your feedback by:

• Responding to the short survey below
• Provide written feedback by emailing metrowater.infrastructure@epa.nsw.gov.au

Sydney Water’s sewage treatment systems cover a wide area of Greater Sydney and the Illawarra ranging from Brooklyn on the Hawkesbury River to the north, the Blue Mountains to the west, and Gerringong/Gerroa in the south.

We're the primary environmental regulator for New South Wales. We partner with business, government and the community to reduce pollution and waste, protect human health, and prevent degradation of the environment.

The majority of Australian sewerage systems consist of a combination of gravity-based and pumping infrastructure which delivers sewage flows to treatment plants from which the treated effluent is reused or disposed of via discharge to inland waters or the ocean.

Sydney Water owns and operates sewage treatment systems across the Sydney, Illawarra and Blue Mountains areas.

We issue licences to persons or organisations conducting “scheduled activities”. These activities are specified in legislation and include sewage treatment.

These licences contain conditions that the licence holder must comply with. These conditions can vary according to site specific requirements and contain performance requirements, operating conditions and pollution limits.

These licences cover Sydney Water’s sewage treatment plants (STPs), and the associated network of sewer pipes, sewage pumping stations and overflow structures (reticulation system).

Of these 23 sewage system licences, eight are for STPs that discharge to the ocean, with the remaining 15 discharging to the Hawkesbury-Nepean River and its tributaries. These licences do not cover the stormwater system, typically regulated by the local Council.

Each Sydney Water licence contains limits on the pollutants permitted to be discharged to the environment from STPs. These limits are based on several factors including:

• The receiving water type
• Ambient water quality
• The STP’s designed hydraulic and treatment capability, and
• The potential pollutants present.

Examples of key water pollutants for smaller STPs include suspended solids and nutrients such as nitrogen and phosphorus. Larger STPs have additional key pollutants including heavy metals such as cadmium, copper and lead.

These limits apply to both the concentration of these pollutants and the annual quantity (load) of pollutants. Concentration limits help protect the environment in the short term, whilst load limits help protect the long-term health of the environment.

Several conditions relate to how Sydney Water must maintain and operate its STPs and reticulation networks. Sydney Water also must ensure that their systems do not deteriorate and that they continually improve their environmental performance.

Each licence contains conditions relating to the level of treatment required. This can be based on several factors including the:

• Capacity and efficiency of the plant
• Flow rate of wastewater entering the plant
• Quality of the wastewater entering the plant, and
• Amount of dilution and impacts on water quality from high rainfall events.

The EPA drives continuous improvement in plant treatment capabilities and updates these conditions after any plant upgrades to ensure that each licence reflects the highest level of treatment available.

When the sewerage reticulation network is blocked or full, wastewater can ‘overflow’ from pipes to the local environment or within private properties. These overflows can occur in both dry and wet weather.

Most overflows in dry weather are caused by blockages from tree roots, fats, wet wipes and other materials that do not break down in the sewer.

Wet weather overflows are caused by stormwater inadvertently entering the sewerage system from a range of sources (including illegal private stormwater connections, faulty sewer openings and damaged pipes) and causing the capacity of the system to be exceeded.

The system is designed so that excess diluted sewage is directed to designed overflow structures that discharge into waterways rather than overflowing into homes, backyards, businesses and public spaces which may cause a public health issue.

Each licence specifies what discharges are permitted and under what circumstances, with the aim of minimising overflows to the environment. They also contain comprehensive reporting and monitoring requirements in relation to overflows.

For example:

• Dry weather overflows from sewage pumping stations that reach waterways are not permitted, and
• Sydney Water implements an Aquatic Monitoring Program, which has the objective to assist the EPA in identifying areas requiring improvement, reoccurring and/or emerging issues and/or trends in pollution concentrations, water quality and ecosystem health.

Sydney Water employs a range of odour controls and mitigation measures across a wide range of activities that have the potential to generate odour, such as STP operations, operation of the sewage reticulation system, and biosolids management.

Sydney Water’s licences do not usually contain conditions relating to odour, as they have an obligation under the Protection of the Environment Operations Act 1997 to not cause or permit offensive odours being emitted from their Premises.

Sewage treatment is generally considered to have lower risks of offensive noise compared to other industrial activities and noise issues are generally dealt with on an individual basis.

We progressively amend licences to ensure they require continuous improvement. We're implementing a range of strategic programs through licence conditions aimed at improving the environmental performance of Sydney Water’s sewage treatment systems.

We have implemented the Hawkesbury Nepean nutrient framework on the licences for Sydney Water’s plants that discharge treated effluent to the river. The framework caps nutrient (nitrogen and phosphorous) loads and addresses concentration levels discharging into the river catchment.

The framework commences 1 July 2025. It is intended that the loads permitted to be discharged from the plants decrease over time to meet the community’s values for the river.

As required under its environment protection licences, Sydney Water is implementing a risk-based approach to reducing sewage overflows that occur during dry weather due to blockages or “chokes”.

The choke regulatory framework aims to reduce the impacts of overflows from chokes across Sydney Water’s network by prioritising areas where chokes pose the greatest risk of impact. Sydney Water implements a range of measures to achieve this aim including preventative maintenance, monitoring, and relining pipes.

Sydney Water’s licences also include a framework that requires Sydney Water to review and improve its processes to prioritise areas of its network for wet weather overflow abatement. This ensures that the regulation and management of these overflows focuses on areas of high impact to public health and the environment.

Actions to reduce the impacts of wet weather overflows include network upgrades to reduce rainwater infiltration to the sewer and improve the operation of emergency relief structures (i.e. designed overflow points in the sewer network).

Our objectives include protecting and improving waterway environmental values and ensuring continuous improvement in environmental risks.

STP discharges can impact on water quality and human health such as by:

• disease-causing micro-organisms
• direct toxicity of the pollutants released, such as ammonia, heavy metals, pesticides and commonly used chemicals
• sediment which causes turbidity affecting aquatic insect habitats
• nutrients such as nitrogen and phosphorus causing algal blooms
• organic matter reducing dissolved oxygen levels needed for fish and aquatic insects, and
• bioaccumulation which leads to adverse effects over time on ecosystems and human health
• the impacts of the pollutants discharged
• which pollutants discharged from which location pose the highest environmental risk, and
• the measures that can be implemented to effectively reduce these risks in the short and long-term.

The EPA is proposing to examine further Sydney Water’s concentration and load limits with a future thinking, whole of system approach. This approach will focus on:

• the impacts of the pollutants discharged
• which pollutants discharged from which location pose the highest environmental risk, and
• the measures that can be implemented to effectively reduce these risks in the short and long-term.

Should you have any concerns about Sydney Water’s operations, including noise or odours impacting you, please consider reporting your concerns to Sydney Water on 13 20 92 or to the EPA on 131 555. This will help us assist you in a timely manner.

The EPA investigates non-compliant discharges and incidents in accordance with its Regulatory Policy. Compliance and enforcement actions may include advisory letters, penalty notices, prosecution, additional licence conditions, and/or a requirement to complete a pollution reduction program.

Please note, your feedback may include ‘personal information,' including your name, address, email, internet protocol address and any other personal information contained in your feedback.

The NSW Environment Protection Authority (the EPA) must comply with the Privacy and Personal Information Protection Act 1998. Visit the EPA’s privacy page and the Privacy Policy for further information on its online consultation platform.

The EPA may publish all or part of your feedback on its website, on its online consultation platform or in a consultation report. In providing us with your feedback, you consent to the EPA publishing all or part of your submission. If you would like all or part of your feedback to be withheld from publication, please let us know when making your feedback.

If you send us an email, we will record your email for the purpose of responding to you.

All information held by the EPA is subject to the Government Information (Public Access) Act 2009.