In July 2024, Sydney Water faced a crisis after detecting dangerously high levels of PFAS chemicals in drinking water in the Blue Mountains. 41,000 homes in areas such as Blackheath, Leura, Mount Victoria, Catalina and Katoomba had probably been drinking water with high levels of PFAS for decades. In late 2024, the NSW Government installed a $3.5 million mobile water treatment plant using Granular Activated Carbon and Ion Exchange Resin at Cascade Water Filtration Plant in an attempt to resolve the contamination. The NSW Government has also committed $80-$100 million for an upgrade to Cascade which should be operational by 2026-2027.
Sydney Water began publishing some PFAS detections in 2024 (North Richmond WFP was tested for in 2019 & 2023), but Friends of the Earth applied under GIPA legislation to gain access to the full suite of detections in late 2024. In 2025 Sydney Water started publishing all their PFAS detections via their website. The following information has been compiled from these published results, some of the most extensive PFAS testing in the country. (As a comparison, the Water Corporation in Western Australia refuses to release any PFAS information, including under Freedom of Information legislation).
In June 2025, the National Health and Medical Research Guideline updated Australian Drinking Water Guidelines (ADWG) for PFOA (perfluorooctanoic acid): 200 ng/L (0.2μg/L), PFOS (perfluorooctane sulfonic acid): 8 ng/L (0.008μg/L), PFHxS (perfluorohexane sulfonic acid): 30 ng/L (0.03μg/L), PFBS (perfluorobutane sulfonic acid): 1000 ng/L (1μg/L), GenX chemicals (hexafluoropropylene oxide dimer acid and its ammonium salt): no health-based guideline value can be derived at this time.
Sydney Water have detected 10 PFAS chemicals, meaning that six of these have no guidelines published in the Australian Drinking Water Guidelines.
Water Filtration Plants where PFAS has been detected
The Sydney Water data can be divided into weekly test results which are published for Blackheath, Katoomba and North Richmond. The other locations are tested once a month. Because of this, average detections for the year have been used. Water NSW have also tested across reservoirs supplying Sydney Water, but results have only been published up to September 2025 and have not been included in this blog (except for Wingcarribee WFP). It should also be emphasised that testing only occurs in raw water prior to water treatment. Water treatment varies and different water treatment types are more successful than others in removing PFAS.
Surprisingly, the highest average PFAS detections were at Woronora and Prospect Water Filtration Plants (WFP). Both WFP's had the PFAS chemical PFBA (Perfluorobutanoic acid) dominate detections. Of the eleven locations, PFBA dominated PFAS detections at eight Sydney Water Filtration Plants. Prospect WFP supplies drinking water to 85% of Sydney's population (4.7 million people). There is no drinking water guideline in Australia for PFBA even though it is easily the PFAS chemical impacting drinking water supplies in Sydney to the highest amounts. Also note the 9 different PFAS chemicals detected at North Richmond WFP, the only WFP sourcing water from the Hawkesbury River. Note also that Blackheath and Katoomba are supplied by Cascade WFP. Cascade Outlet only had 9 test regimes in November and December. Macarthur refers to both Appin and Campbelltown.
Woronora supplies drinking water to residents in the Sutherland Shire and also northern suburbs of Wollonongong. Woronora is the sole supplier of drinking water to Helensburgh, Engadine and Lucas Heights. Woronora Dam was completed in 1941 and has a catchment of 75 sq km.
97% of PFAS detections at Woronora WFP were for PFBA. What was the source of PFBA at Woronora and other mainly forested catchments? Friends of the Earth theorised in early 2025 that PFBA sources in Sydney drinking water supplies could be coming from atmospheric deposition. From the 12 separate Sydney Water tests conducted at Woronora in 2025, there were 8 detections of PFBA with the highest amount 0.065μg/L detected in July 2025.
PFBA is a breakdown product of other PFAS chemicals and is a short-chain PFAS chemical. It was also used in the manufacturing of photographic film and has been used as an alternative to longer chain PFCA's (perfluroalkyl carboxylic acids). This description however doesn't fully explain why it is the predominant PFAS chemical in the Sydney water supply, particularly in catchments that are largely forested. PFBA is known as a ubiquitous, mobile and persistent contaminant in the atmosphere and has a high propensity for atmospheric transport. PFBA can be created through industrial manufacturing processes, off-gasing from consumer materials such as carpets, textiles and fire fighting foams. Other sources include landfills and waste water treatment plants. PFAS chemicals including PFBA can exist in gaseous or particulate form with wind direction one of the key influencing factors.
A study in China in winter found that PFBA had the highest atmospheric concentration of all the PFAS chemicals.
Scientific evidence points towards developmental, thyroid and liver effects that are likely caused by PFBA in utero or during adulthood. These affects are based on animal experiments.
The same information as the first graph, but with detections of the four PFAS chemicals that have guidelines under the Australian Drinking Water Guidelines. The highest average detections were at North Richmond WFP reaching almost 0.006μg/L. The highest detection of PFOS at North Richmond was 0.0051μg/L (63.75% of ADWG) on the 21st of October.
By dividing the average PFAS detection with the PFAS drinking water guideline levels, it is apparent that the main PFAS chemicals of concern are PFOS (Perfluorooctanesulfonate) and PFHxS (Perfluorohexanesulfonic Acid) which is not surprising considering their lower guideline levels of 0.008μg/L for PFOS and 0.03μg/L for PFHxS. North Richmond combined PFAS detections in raw water are therefore are averaging <30% of the Australian drinking water guidelines. These levels are likely to be reduced somewhat by water treatment.
Comparing average PFAS detections over 2024* and 2025, the main PFAS chemicals of concern in the Blue Mountains PFHxS and PFOS have reduced substantially since the implementation of the portable water treatment plant was made operational in late 2024. (PFAS detections at Cascade are only available since June 2024, so levels were likely to be higher previous to June 2024). For an unknown reason however, average PFBA detections remain approximately the same.
Comparing average PFAS detections over 2024* and 2025, the main PFAS chemicals of health concern for Prospect/Warragamba/Orchard Hills, PFHxS and PFOS have remained approximately the same. (PFAS detections for all three are only available since June 2024 and Water NSW detections have been included in the 2024 graph). For an unknown reason PFBA detections at Prospect/Warragamba & Orchard Hills were almost zero in 2024. Average levels of PFOA, PFxS, PFOS and PFBS are well under drinking water guidelines.
Total amounts of PFAS chemicals detected at Warragamba, Orchard Hills and Prospect are similar except for an obvious spike in detections of PFBA at Prospect. More than 80% of Sydney's drinking water comes from Warragamba Dam and is then treated at Prospect WFP. 20-40% of Sydney's water is also supplied by the Upper Canal system which connects the Upper Nepean Scheme with Prospect. Is the PFBA spike at Prospect due to water coming in from the Upper Nepean? Probably. 97% of total PFAS detected at Nepean WFP in 2025 was dominated by PFBA, with 93.4% detected at Macarthur Appin being PFBA with lesser percentages at Macarthur Campbelltown. Plans to increase Purified Recycled Water via the Advanced Water Treatment Facility at Quakers Hill may also have unforseen PFAS issues.
Lake Wallace in the upper reaches of the Coxs River. The township of Wallerawang is to the west of the lake. Are mines and other land uses in this area the source of ongoing PFAS pollution in Warragamba dam?
Warragamba dam is supplied by the Coxs River catchment, which has a number of land uses in the upper reaches of the catchment including mining and urban development (eg Lithgow waste water treatment plant). It is interesting to note that the major dams on the Coxs River (Lake Lyell & Lake Wallace) have never been tested for PFAS. Wallerawang Power Station was also located just upstream of Lake Wallace. Power Stations and Mining operations are common sources of PFAS chemicals.
In terms of total amounts of PFAS detected at Richmond WFP, PFBA made up 33% of all PFAS chemicals, with PFOS just over 10%. This highlights 9 different PFAS chemicals in the Hawkesbury River. What is the source of these chemicals?
In terms of total amounts of PFAS detected at Cascade WFP, PFBA made up almost 73% of all PFAS chemicals, with PFOS just over 14.6%.
The highest PFOS average detections are North Richmond followed closely by Cascade WFP (Blackheath and Katoomba). Average PFOS detections at North Richmond are 0.001564μg/L or 19.5% of the ADWG. Average PFOS detections at Prospect are 0.0007μg/L or 8.75% of the Australian Drinking Water Guidelines, with the highest detection of 0.0011μg/L (13.75% of ADWG) on September 15. Illawarra and Nepean WFP's appear to be lowest risk of PFOS contamination. PFOS detections at North Richmond indicate ecological contamination of the Hawkesbury River at 6.7 times the PFOS 99% ecological default guideline.
The highest PFHxS average detections are North Richmond followed by Cascade WFP (Blackheath and Katoomba). Average PFHxS detections at North Richmond are 0.002347μg/L or 7.8% of the ADWG. Average PFHxS detections at Prospect are 0.000783μg/L or 2.61% of the Australian Drinking Water Guidelines. Woronora, Illawarra, Nepean and Wingcarribee WFP's appear to be lowest risk of PFHxS contamination. The highest PFHxS detection at North Richmond was 0.0075μg/L (25% of ADWG) on December 2nd.
The highest PFOA (Perfluorooctanoic acid) average detections are North Richmond followed Orchard Hills and Warragamba. Average PFOA detections at North Richmond are 0.001062μg/L or 0.5% of the ADWG.
The highest PFBS (Perfluorobutanesulfonic acid) average detections are North Richmond. Average PFBS detections at North Richmond are 0.000785μg/L or 0.0785% of the ADWG.
The highest PFBA average detections are Woronora and Prospect. There is no drinking water guideline for PFBA in Australia. The average level of PFBA at Woronora is more than 10 times the average level of PFOS.
The highest PFHxA (Perfluorohexanoic acid) average detections are at North Richmond. There is no drinking water guideline for PFHxA in Australia.
The highest PFPeA (Perfluoropentanoic acid) average detections are at North Richmond. There is no drinking water guideline for PFPeA in Australia.
The highest PFHpA (Perfluoroheptanoic acid) average detections are at North Richmond. There is no drinking water guideline for PFHpA in Australia.
Testing in Sydney Drinking Water
Sydney Water PFAS testing has mainly occurred in raw water, prior to treatment. However, this testing may not actually capture PFAS in water coming through residents taps. PFAS removal from raw water at water treatment plants will be dependent on the type of treatment used. The most successful way to treat PFAS will be with Granular Activated Carbon (GAC) and Ion Exchange Resin. Sydney Water does not provide easy access to information pertaining to different treatment options used at various treatment plants, but it would be assumed that most would employ GAC. Standard water treatment plants, not employing GAC, only 'remove' approximately 50% of PFAS chemicals.
Researchers from the University of New South Wales investigated PFAS levels in Sydney tap water in February 2024 and found 31 PFAS chemicals, including 21 additional PFAS chemicals compared to previous studies done in Australia. They also detected 3:3 FTCA for the first time in a water supply in the world and 6:2 diPAP for the first time in tap water. PFAS levels were also higher than what had been detected in raw water. The authors wrote: “that removal or addition of some PFAS is occurring from the water source after treatment but prior to our sampling at the tap…. When loose deposits are present in pipes, such as sediment, mineral buildup or rust, PFAS can accumulate on these deposits, and the subsequent release of these PFAS can change the profile of PFAS detected from the same drinking water source.”
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