PFAS and drinking water

Delivering on our customers' top priorities

Since 2022, we have directly connected with more than 13,000 customers through our customer engagement initiatives to ensure we're delivering on our customers' priorities. What we heard was clear: our customers want safe, clean, reliable drinking water every day.

We continuously review and improve our practices. We closely monitor science and research to ensure we identify new hazards and stay ahead of any potential risks. As we learn more, we may adapt our practices.

The quality of our drinking water is closely monitored by qualified scientists and highly trained specialists in our National Association of Testing Authorities (NATA) certified state-of-the-art laboratories. We test the drinking water produced by our water filtration plants for PFAS and publish the latest results as part of our commitment to water quality.

We use the most advanced research and testing methods to detect and measure trace amounts of substances like PFAS. In fact, we conduct our tests so stringently that they pick up PFAS levels that are almost undetectable, and significantly lower than what is regulated. We test the drinking water produced by our water filtration plants for PFAS and publish the latest results as part of our commitment to water quality.

PFAS are man-made chemicals found in many everyday products. They've been widely used in many industrial and consumer applications as they're effective at resisting heat, stains, grease and water.

PFAS have been used in some common consumer products, including but not limited to:

• firefighting foams
• non-stick cookware like Teflon
• waterproof clothing
• cosmetics and sunscreen
• food packaging, such as grease-resistant wrappers and takeaway coffee cups
• stain-resistant carpets and upholstery.

What is unique about PFAS?

The properties that make PFAS useful in industrial and consumer products can also make them problematic in the environment. PFAS don't break down readily and they're highly mobile in water. This means they travel long distances from their source, and don't break down fully in the environment.

Australia, which hasn't manufactured PFAS, has a significantly lower level and spread of PFAS contamination than other countries like the United States.

From 1 July 2025, the Australian Government banned the manufacture, import, export or use of PFOS, PFOA and perfluoro­hexane sulfonate (PFHxS), and any products that contain them.

The NSW Government is coordinating a multi-agency response to PFAS, informed by the best science and evidence. The government is committed to transparency, ensuring the community has access to up-to-date information and supporting water utilities to deliver safe drinking water. Find out more at PFAS and drinking water – information and updates.

To ensure the safety of drinking water and provide a basis for determining the quality of water supplied to consumers throughout Australia, the National Health and Medical Research Council (NHMRC) developed the ADWG. The ADWG undergo rolling revisions to ensure they represent the latest available scientific evidence on safe drinking water. They're used by state and territory health departments, drinking water regulators, local health authorities and water utilities like us.

The ADWG and PFAS values

In 2018, for the first time, the ADWG included maximum health-based values for perfluoro­octanoic acid (PFOA), perfluoro­octane sulfonate (PFOS) and perfluoro­hexane sulfonate (PFHxS) in drinking water. The values were derived using tolerable daily intake (TDI) values recommended by the Australian Department of Health and Aged Care. In June 2025, the NHMRC added perfluoro­butane­sulfonic acid (PFBS). It now recommends new lower PFAS values for drinking water.

The latest PFAS values are expressed in nanograms per litre. One nanogram per litre (ng/L), or one thousandth of a microgram per litre (µg/L), is the same as one part per trillion (ppt). This is the equivalent of one drop in 20 Olympic-size swimming pools.

We can confirm that our 9 water filtration plants are supplying drinking water below the ADWG PFAS values.

The Water Services Association of Australia provides a detailed PFAS fact sheet that outlines the process of guideline development in the Australian context.

The guideline PFAS values have been calculated for a lifetime of exposure. There's more information on how the values are worked out in the NHMRC Review of PFAS in Australian drinking water.

It's important to know that the ADWG only apply to treated water. This is the water we supply to you. We ensure that all your treated drinking water meets the guidelines, and we report our ongoing PFAS monitoring results for treated water.

The water found in dams and other catchments is untreated water. Untreated water, or raw water, is managed by WaterNSW and is not subject to the ADWG. WaterNSW conducts ongoing PFAS monitoring of the Blue Mountains and Greater Sydney catchments and publishes PFAS results for untreated water on its website.

We've been working to lower PFAS levels in the Blue Mountains. Greaves Creek and Medlow dams remain isolated from the supply while WaterNSW completes detailed site investigations into the source of elevated PFAS levels in the Blue Mountains catchment area. You can read about the Blue Mountains PFAS investigation.

Cascade Water Filtration Plant

We began testing treated water at the Cascade Water Filtration Plant in June 2024, with weekly testing starting on 3 October 2024. Our water systems are dynamic. Residents in the Blue Mountains may receive water from either the Cascade or Orchard Hills water filtration plant. The interconnection between the Cascade and Orchard Hills systems varies depending on operational needs and storage capacity.

Purpose-built treatment system

A treatment system to remove PFAS has been operating at the Cascade plant since December 2024. The $3.4 million treatment system uses granular activated carbon (GAC) and ion exchange resin to remove PFAS. It has a 10-year design life.

Testing and regular monitoring have confirmed the treatment system is effectively reducing PFAS and supporting the continued supply of safe drinking water to the Blue Mountains community.

Separately, Sydney Water is planning substantial future improvements to the Cascade Water Filtration Plant focused on improving source water quality and ensuring the Blue Mountains water supply remains reliable for the future.

This long-term planning will help us continue to deliver high-quality drinking water and meet the needs of the local community for years to come.

For more information, see our October 2026 community update on PFAS treatment at Cascade Water Filtration Plant.

In April 2025, we conducted targeted PFAS monitoring across 54 sites in the Blue Mountains, including reservoirs and customer taps. All customer tap samples met guideline values.

Two intermittently used reservoirs – Jamieson and Shipley – returned results that met the ADWG at the time of testing but exceeded the updated (now current) guideline value for PFOS. These reservoirs supply a very small number of customers and are used infrequently.

As a precaution, we isolated both reservoirs from the drinking water supply on 3 May 2025.

In September 2025, the reservoirs were emptied, cleaned, disinfected and recommissioned following water quality testing. All recommissioning results met the ADWG. In addition, we collected and tested the sediment found within the reservoirs.

The concentration of PFAS in the sediment removed from the reservoirs was below the EPA Waste Classification Guidelines. It was disposed of appropriately.

While PFAS were detected in the sediment, the drinking water supplied from the reservoirs met the ADWG in place at the time of testing, which are designed to protect public health.

It's important to note that concentrations in sediment cannot be directly compared to the ADWG.

What has been done with the sediment?

We've referred to the NSW Environment Protection Authority (EPA) Waste Classification Guidelines to determine the appropriate disposal method for the sediment. These guidelines state that any waste containing 1.8 mg/kg or less of PFOS + PFHxS can be disposed of as general solid waste to landfill. Our sediment testing results for PFOS + PFHxS were well below this limit, meaning the material is classified as safe for disposal under the EPA criteria.

The guidelines don't specify limits for the remaining PFAS compounds tested, so these compounds are marked 'N/A' in the full sediment test results for Jamieson and Shipley reservoirs (17 KB, XLSX).

In 2018, the community raised concerns that PFAS from the Royal Australian Air Force (RAAF) Base Richmond could contaminate drinking water. In 2019, we undertook a targeted monitoring program to assess the potential for this to be the case. Our North Richmond Water Filtration Plant sources raw water from the Hawkesbury-Nepean River 13 kilometres upstream of where the water from the RAAF drains into the river. Therefore, low readings were consistent with expectations.

Following the 2019 study, we conducted an annual monitoring program for the North Richmond plant. This commenced in November 2023. Since October 2023, we've conducted weekly testing of treated water at the plant.