A UNSW analysis of Sydney water has found at least 31 PFAS chemicals, including 21 not previously recorded in Australian tap water, and one detected in tap water globally for the first time.
Researchers from UNSW Sydney have identified 21 new PFAS chemicals in Sydney's tap water, bringing the known total to 31 types.
While official health guidance says there is currently limited evidence of human disease or other clinically significant harm resulting from PFAS exposure, the scientists say their findings reinforce the need for broader monitoring.
In a study published today in the journal Chemosphere, the researchers flag two of the new PFAS chemicals as being of interest. One compound, 6:2 diPAP, has previously been found in bottled water and other consumer environments but not in tap water. The other (3:3 FTCA) has until now, never been found in Australian tap water, and has only once before been reported in a drinking water supply worldwide.
PFAS compounds – or per- and polyfluoroalkyl substances – are often dubbed 'forever chemicals' because they don't break down naturally and persist in the environment and human body for decades.
While they can be a health concern, current exposure through drinking in Australia is generally considered low, and Australian guidelines are designed to minimise risk over a lifetime. However, the WHO and other global and national authorities continue to monitor and reassess their safety.
Lead author Professor William Alexander Donald from UNSW's School of Chemistry said PFAS profiles depended on catchment, with higher concentrations near likely contamination sites.
"Sydney's water meets current Australian standards, but when considering health benchmarks used in other countries, some samples were near or above safety limits," he said.
"Detecting PFAS not previously reported in tap water highlights that our monitoring programs are now uncovering more of the chemicals present in our supply."
PFAS have been widely used in firefighting foams, non-stick cookware, waterproof materials, and industrial manufacturing. Around the world, PFAS detections near airports, military bases, and landfills have triggered tightening regulations.
Key findings
The researchers analysed 32 tap water and 10 bottled water samples taken from the Sydney water catchment areas in early 2024 including 10 sites in the Ryde catchment, 13 in Potts Hill, four in Prospect and five in North Richmond. They found PFOS – a legacy firefighting foam chemical and known carcinogen – in some North Richmond samples with a reading of 6 parts per trillion (ppt), which is 2 ppt below Australia's guidelines of 8 ppt, but higher than the US EPA's advisory limit of 4 ppt.
Other significant findings were the first-ever detection in Australian drinking water of 3:3 FTCA, a short-chain breakdown product from firefighting foams. There is currently no established toxicity data or regulatory limit for this specific compound in drinking water, although its presence raises concern due to its chemical similarity to other PFAS known to pose health risks.
"We were also surprised by finding 6:2 diPAP," Prof. Donald said. "This study reports the first detection of this PFAS in tap water globally."
The researchers say limited evidence from early studies suggests 6:2 diPAP may affect thyroid and reproductive systems, but caution that further research is needed.
The most abundant compound detected on average – and present in every tap water sample – was PFBA, a short-chain PFAS. It's a common breakdown product of other PFAS and is now attracting scientific attention because they're increasingly used as replacements for regulated long-chain PFAS, yet remain highly mobile in water and environmentally persistent. While PFBA builds up in the body less than longer-chain PFAS, the researchers noted that some early studies suggest potential effects on liver, thyroid, and developmental health.
Sampling and testing
Leading the laboratory analysis was Dr Lisa Hua, who was previously part of the team that detected PFAS chemicals in the mysterious black blobs washing ashore on Sydney's beaches last summer. She used specialised resins that were able to extract PFAS compounds from water samples brought back to the lab.
To detect PFAS, Dr Hua used a technique called mass spectrometry that identifies chemicals by measuring the weight of their molecules. The method is so sensitive it can pick up PFAS at parts per trillion, which is like finding a single drop of water in 20 Olympic-sized swimming pools.
"It should be reassuring that these PFAS concentrations are low, however, we should explore new technologies that remove PFAS before their release into our ecosystems and drinking water supply," Dr Hua said.
Prof. Donald added that because the 31 PFAS found are chemically so similar, it makes regulation more difficult.
"This highlights that we are stuck in a whack-a-mole situation with PFAS," he said.
"Tiny tweaks to the chemical structure create a 'new' compound, but the toxicology research and regulatory work has to start all over again every time a PFAS is tweaked."
The researchers say this fragmented approach to PFAS regulation presents a growing challenge, especially as more of these compounds are now detectable at trace levels in the environment. Many PFAS differ only slightly in structure, yet each variant must undergo its own assessment for toxicity, environmental persistence, and potential health impacts before it can be considered for regulation. Europe has already moved towards regulating PFAS as a class rather than individually, which could help reduce the regulatory burden and provide a more proactive approach to the issue.
Where to now?
Earlier this year, the researchers published a study in the Journal of Hazardous Materials identifying a material that, when added to water at trace levels, can remove more than 99% of PFAS at environmentally relevant concentrations. In collaboration with other scientists, they are now also working on materials designed to absorb PFAS from water and break it down entirely.
Other proposed next steps include expanding PFAS monitoring across Australia. This could involve a nationwide survey to assess PFAS levels in both urban and remote areas, helping to establish a more complete baseline.
The researchers recommend that monitoring be broadened to include more PFAS compounds, which would help generate more comprehensive data tracking over time.
"Expanding the current monitoring of PFAS could be beneficial to gain a greater understanding of seasonal variations of PFAS in drinking water supply," Dr Hua said.
Breakout: How world PFAS regulations compare:
U.S. EPA: enforceable limits for PFOS/PFOA set at 4 ppt
EU: implementing sum‑total PFAS limits from 2024 – meaning the EU will regulate PFAS as a group, setting a combined limit for multiple chemicals rather than individual ones.
Australia: current PFOS limit set to 8 ppt in 2025 (down from 70 ppt), higher than U.S. standards
