A recent Australian study has revealed that Sydney’s drinking water contains 31 different per- and polyfluoroalkyl substances (PFAS), including two compounds never before reported in global tap water supplies. While most concentrations were below both U.S. (4 ppt) and Australian (8 ppt) regulatory limits, samples from North Richmond exceeded U.S. Environmental Protection Agency (EPA) thresholds.
The research, published in Chemosphere in 2025 by scientists from the University of New South Wales, is the most extensive survey of PFAS in Sydney’s tap and bottled water to date. It detected a total of 31 PFAS from a list of 50 tested compounds in 32 tap water and 12 bottled water samples. Among these were 3:3 fluorotelomer carboxylic acid (3:3 FTCA) and a fluorophosphoric acid diester (6:2 diPAP). Both have limited toxicity data, but their discovery highlights the ongoing evolution of PFAS pollution as older “legacy” chemicals like PFOA and PFOS are phased out and replaced.
- 31 PFAS detected in Sydney tap water, including 21 never before reported in Australian tap water.
- The PFAS called 3:3 FTCA was identified for the first time in any drinking water globally.
- The PFAS called 6:2 diPAP was identified for the first time in tap water.
- North Richmond samples contained PFOS above U.S. EPA limits but below Australia’s current (2025) guidelines.
- 3:3 FTCA and 6:2 diPAP was detected in most of the bottled water samples.
Sampling Sydney’s Water
Sampling took place across the Greater Sydney basin, including catchments at Ryde, Potts Hill, Prospect, and North Richmond. Researchers also tested major bottled water brands representing more than 80% of the Australian market. Using ultra-trace detection methods capable of measuring as low as 0.031 parts per trillion (ppt), the study found that some PFAS profiles in tap water differed from their original catchment sources.
The most common and highest concentration PFAS was perfluorobutanoic acid (PFBA), detected above quantification limits in every tap water sample, averaging 5.2 ppt. PFBA is a common degradation product of many PFAS (e.g., PFCAs, diPAPs), which may explain why high concentrations of it were found in the tap water. While PFBA currently has no U.S. or Australian drinking water guideline, studies have raised concerns about its potential health effects, including oxidative stress in human cells (Obiako et al., 2024).
PFOA and PFOS, the two PFAS most strictly regulated worldwide, were found in 97% and 91% of samples respectively, though at relatively low average concentrations (0.66 ppt for PFOA and 1.4 ppt for PFOS). However, certain North Richmond samples contained PFOS at 6 ppt, above the U.S. EPA limit of 4 ppt, but still within Australia’s 2025 threshold of 8 ppt.
Why North Richmond Stands Out
North Richmond is located about 35 miles (56 km) north west of the center of Sydney.
North Richmond’s water supply, sourced from the Hawkesbury-Nepean River, has a documented history of PFAS contamination linked to firefighting foam use at a nearby military base (Thomson et al., 2011). The study found that average PFOS levels there were 4.1 ppt, with peak values reaching 6 ppt.
Researchers suggest that flood events and stormwater runoff may periodically wash PFAS into the catchment, with possible remediation options including PFAS-targeting flocculants, activated carbon filtration, and novel metal-organic framework adsorbents.
PFAS Found In Bottled Water
PFAS were also found in bottled water, though generally at lower concentrations than in tap water. PFOA was detected in all bottled samples (average 0.53 ppt), while PFOS was absent. 3:3 FTCA and 6:2 diPAP were both present, marking the first known detection of 3:3 FTCA in bottled water globally.
The detection of PFAS in bottled water is consistent with findings from international studies, where contamination often stems from processing, packaging materials, or the source water itself.
U.S. vs Australian Guidelines
The timing of the study coincides with major shifts in PFAS regulation.
In 2024, the U.S. EPA set legally enforceable maximum contaminant levels of:
- 4 ppt for both PFOA and PFOS, and
- 10 ppt for PFHxS, PFNA, and GenX.
Australia’s 2025 update, however, retained much higher limits:
- 200 ppt for PFOA,
- 8ppt for PFOS,
- 30 ppt for PFHxS, and
- 1000 ppt for PFBS.
This means that water considered compliant under Australian law could exceed U.S. safety limits by a wide margin. For example, the 6 ppt PFOS found in North Richmond would be 50% over the U.S. legal threshold.
Why So Many Types Of PFAS?
The appearance of “emerging” PFAS like 3:3 FTCA and 6:2 diPAP in Sydney water is linked to the breakdown of other PFAS used in firefighting foams, industrial coatings, and even everyday products such as non-stick cookware, textiles, and food packaging. These compounds are persistent in the environment, can travel long distances in water, and resist conventional water treatment methods.
For example, 3:3 FTCA is a degradation product of 6:2 FTSA, itself used in industrial processes and firefighting foams. 6:2 diPAP has been found in dust, paints, and even toilet paper, and can degrade into more persistent PFAS.
Why This Matters For Those In The U.S.A
While this is an Australian study, its findings are highly relevant to the U.S. The detection of PFAS above U.S. limits in an advanced economy with modern water treatment infrastructure highlights how difficult it is to fully eliminate these chemicals from drinking water.
In the U.S., water utilities are now preparing to meet the EPA’s strict 4 ppt standard for PFOA and PFOS, a requirement that will drive significant investment in filtration technology. The Sydney findings suggest that even with high-quality treatment, short-chain PFAS and previously unmonitored compounds may still be present. It also suggests that the regulatory frameworks will need to keep evolving.
References:
Hua, L. and Donald, W.A., 2025. Assessment of per-and polyfluoroalkyl substances in Sydney drinking water. Chemosphere, p.144611. https://doi.org/10.1016/j.chemosphere.2025.144611
Obiako, P.C., Ayisire, S.O. and Sayes, C.M., 2024. Impact of perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) on oxidative stress and metabolic biomarkers in human neuronal cells (SH-SY5Y). Environment International, 190, p.108864. https://doi.org/10.1016/j.envint.2024.108864
Thompson, J., Eaglesham, G. and Mueller, J., 2011. Concentrations of PFOS, PFOA and other perfluorinated alkyl acids in Australian drinking water. Chemosphere, 83(10), pp.1320-1325. https://doi.org/10.1016/j.chemosphere.2011.04.017