18/1/24: TasWater PFAS detections 2017-2023

TasWater PFAS detections 2017 – 2023

18/1/24: https://www.foe.org.au/taswater

By Anthony Amis

In October 2023, a Right to Information (RTI) request was sent to TasWater requesting data regarding PFAS detections by TasWater testing. The information was received from TasWater in less than two months. The following information is most likely the first published regarding PFAS detections by TasWater. Data from the request has also been added to the Australian PFAS map, still the only nation wide database attempting to keep up with the key toxic issue of our generation. FoE has also investigated the PFAS issue in Victoria in past blogs.

For more information on what is PFAS see here.


Above: The locations where positive samples were detected.

TasWater provide drinking water and sewerage services to the Tasmanian community.  TasWater operate 112 Sewerage Treatment Plants (STP’s) throughout the state, the RTI data shows that long term monitoring between 2020-2023 was conducted at 13 STP’s, with a further 16 STP’s tested over a shorter period of time. This means that TasWater currently have PFAS data for a quarter of their sewerage treatment plants. Extremely limited PFAS testing in water supplies was only carried out 4 times at Hobart. Water supplies don’t appear to be of major concern to TasWater in regards to PFAS contamination.


Approximately 88.5% of all test regimes for sludge/biosolids were positive for at least one PFAS chemical and approximately 55% of test regimes in effluent/influent being positive for at least one PFAS chemical.

Almost 2000 individual biosolid/sludge samples tested positive for PFAS.

Only four tests were conducted in a drinking water supply (Hobart) and all were negative.

45% of targeted Trade Waste tests detected PFAS chemicals, sometimes at very high levels.

PFOS was the main PFAS chemical of concern, with by far the highest amounts detected at the Cambridge Sewerage Treatment Plant, located near Hobart Airport. 88% of PFAS detections at Cambridge STP were for PFOS.

76% of all the tested treatment plants would the breach lower end of the proposed National Environment Management Plan (NEMP) guidelines for PFHxS+PFOS for biosolids/sludge. 7% would breach lower end of the NEMP for PFOA.

Cambridge Sewerage Treatment Plant, Ranelagh and St Helens would have exceeded the higher proposed NEMP Guideline of PFHxS + PFOS levels higher than 31μg/kg. Both Cambridge and Blackmans Bay breached the lower end of the scale for PFOA.

The highest PFAS average detections were recorded at Brighton Sewerage Treatment Plant (but from a limited sample size), for Perfluroalkyl Sulfonamides chemicals MeFOSAA, EtFOSAA and MeFOSE.

In April 2020, PFOS was detected at 2,500 times over the 99% ANZECC trigger at Selfs Point Sewerage Treatment Plant, but it is unclear if this testing was conducted in influent, effluent or within the plant itself. Between 2021-2023 however the PFOS averages dropped significantly at Selfs Point to an average of 0.0135μg/L 1.5 times over the ANZECC 99% trigger level.

In 2023 PFHxS in effluent samples at Cambridge STP averaged 0.02125μg/L and the PFOS detections averaged 0.174μg/L, 19 times over the ANZECC 99% trigger level for PFOS.

TasWater information regarding STP influent coming into treatment plants was very limited.

Test Regimes

Most of the testing occurred for 4 separate PFAS groups that include 28 different PFAS chemicals. For the sake of this blog, FoE describes tests that include all 28 separate PFAS chemicals as ‘test regimes’.

The types of PFAS chemicals tested included:

Perfluoroalkyl Sulfonic Acids


Perfluoroalkyl Carboxylic Acids


Perfluoroalkyl Sulfonamides


Fluorotelomer Sulfonic Acids

4:2 FTS, 6:2 FTS, 8:2 FTS, 10:2 FTS

The above graph explains the number of PFAS detections (not volumes). Based on a carbon chain number, PFAS chemicals can be divided into long chain and short chain compounds. Long chain PFAS have a higher bioaccumulation potential. Phasing out of some longer chain types of PFAS chemicals started in the early 2000’s. The TasWater detections are dominated by PFOS, a long chain Perfluoroalkyl Sulfonic Acid.

TasWater PFAS tests did not occur until March 2017. It is highly likely that PFAS compounds would have been present for decades before 2017. Since 2019 most TasWater testing has focused on Sludge/Biosolids at STP’s. Trade Waste test regimes included a suite of 5 chemicals, in comparison to 28 for water/biosolids/sludge. Biosolid/Sludge tests account for 75% of all tests, highlighting where TasWater see the most risk/concerns. It is also worth considering that since 2018 TasWater rarely test for pesticides. As pesticide and PFAS testing is expensive, could it be argued that the budget for pesticides has been consumed by PFAS testing?

Results Sludge/Biosolids

Longer term tests between the years 2020-2023 were conducted at 13 STP’s. PFOS detections accounted for ~73% of the amount of PFAS chemicals by volume. Sewerage sludge is usually defined as raw sludge that contains a range of pollutants. Biosolids are usually defined as sludge that has been treated and stabilised for pathogen reduction. There has been some criticism labelled at the name biosolids, as it implies that toxicants such as PFAS have been removed. Sewerage treatment plant lagoons can also require desludging where solid waste has been created by bacteria when breaking down the waste water. These solids settle at the bottom of the lagoon and form a sludge deposit. The sludge can build up and cause odours and storage capacity problems. Sludge once removed from lagoons is stored to dry for a number of weeks and eventually become biosolids after being stockpiled for a longer period of time. PFAS chemicals, being labelled ‘forever chemicals’ cannot be entirely removed by this process.

The more extended testing regimes found that detections were dominated by Cambridge STP, located close to Hobart Airport. 88% of PFAS detections at Cambridge STP were for PFOS. 59% of PFOS detections across all of the 13 STP’s were detected at Cambridge. The PFOS average detection at Cambridge was 0.172mg/kg. Despite the high levels of PFAS recorded in sludge from Cambridge, TasWater have stated that they have full compliance with the 2022/23 Sewage Sludge Management Plan (SSMP).

For the 3 years of testing, PFOS levels at Cambridge STP remained stubbornly high.

Cambridge Sewerage Treatment Plant in foreground (centre/lower left of image), is located in very close proximity to Hobart airport where PFAS has been a major problem. Biosolids from Cambridge 2022/23 appear to have ended up on a number of farms. Were the the landowners informed of the PFAS content of the biosolids? For how many years/decades have biosolids from Cambridge been sent off site? Biosolids from Cambridge are not stored on site and no stockpiling occurs.

It appears likely that there could be some drainage through the sewer network from Hobart airport that flows into the treatment plant. Cambridge STP is also likely to accept trade waste.  Key influent sources at Cambridge are listed by TasWater as Residential/Industrial (2 x Category 3 Customer, 5 x Category 4 Customer).

Cambridge also releases water into Sinclair Creek that flows into Pitt Water.The Pitt Water and Sinclair Creek have been found to contain PFAS chemicals, with the source attributed to Hobart Airport where aqueous film forming foam (AFFF) has been used in the past.


Biosolids promotional material from 2009/10 shows that Cambridge was the third largest producer of biosolids from Southern Water at that time. PFAS was not an issue then even though its use had been widespread for many years. No water authorities in Australia were testing for it. Legacy use of PFAS contaminated sewerage sludge will be an increasingly fraught issue in the future as widespread contamination is reported. A recent issue has been Westlakes in South Australia. Will water authorities face legal action in the future from landowners whose land has been contaminated by PFAS tainted biosolids?

All of the longer term monitored STP’s followed the same pattern with PFOS dominating sludge/biosolid detections. The one STP which “bucked this trend” was Pardoe Waste Water Treatment plant, located east of Devonport. Pardoe recorded 95% of all Tasmanian STP sludge/biosolid detections of the short chain PFAS chemical 6:2 FTS. 6:2 FTS has largely been used as a replacement for the legacy PFAS chemicals such as PFOS in chrome mist suppressants in the electroplating industry. It is unclear why Pardoe has recorded these levels of 6:2 FTS.

TasWater conducted PFAS in sludge/biosolids testing at 16 STP’s, mostly in 2022/23, but under shorter/less extensive durations. At these locations PFOS was the third highest detected chemical, after EfFOSAA and MeFOSAA. Shorter term monitoring included the following STP’s: Longford, Port Sorrell, Prospect Vale, Legana, Richmond, Campania, St Helens, Queenstown, Perth, Brighton, Cressy, Bicheno, Georgetown, Riverside, Rokeby and Ranelagh.

Of the fewer test results, Brighton Sewerage Treatment was the standout particularly in terms of MeFOSAA and EtFOSAA, but not PFOS. Interestingly Brighton STP also recorded the highest total PFAS average across all STP’s, although testing there was limited.

PFAS regulation of biosolids in Tasmania continues to be a “grey area” and rather vague: “Tasmanian Biosolids Reuse Guidelines, June 2020 p17 “Health based guidance values for PFAS have been recently reviewed by the Australian Government Department of Health. As these values are potentially subject to further modification it is not deemed appropriate to prescribe specific contaminant acceptance thresholds in these guidelines. However, given the paucity of information on concentrations of these compounds in Tasmanian biosolids it is deemed necessary to monitor, assess and, if necessary, determine appropriate management options for any biosolids containing sufficient concentrations of these compounds.

Significant potential sources of these contaminants include airports and industrial premises which need to manage a high fire risk, fire services training grounds and landfill leachate. If the WWTP is serving a larger urban catchment or a catchment containing any of these potential sources, the Producer must sample and analyse the biosolids for these contaminants in accordance with the sampling requirements specified in Appendix B. If found above reporting limits the Producer must provide this information to EPA Tasmania
and discuss appropriate management options.

Ti-Tree Bend Sewerage Treatment Plant in Launceston is perhaps TasWater’s largest producer of biosolids producing about 1200 dry solid tonnes per year or 15% of TasWater’s total.

Ti Tree Bend, like almost all of the Sewerage plants in Tasmania has PFOS as the largest contributor of the PFAS chemicals found in biosolids/sludge. The average PFOS level detected in biosolid monitoring over a 4 year period was 0.01mg/kg or 10μg/kg. PFOS however, contributed only 45% of the total PFAS volume at Ti Tree Bend. Planned PFAS rules likely to be adopted by the PFAS National Environment Management Plan (NEMP), only take into account three PFAS chemicals PFOS, PFHxS and PFOA. Combined these three chemicals contribute over 50% of the Ti Tree Bend PFAS problem but are ignored under the NEMP.

NEMP Quandry

The third version of the PFAS NEMP allows for water authorities to continue to sell contaminated biosolids/soil enhancers to farms and other land owners across the country. Biosolids are a big industry and it would appear that the decades old argument promoting the reuse of biosolids, conveniently avoided the issue of PFAS contamination in the biosolids until recently. The issue of widespread contamination of biosolids and fertilisers with high levels of PFAS simply has not been addressed. Decades of material has already been applied across literally thousands of hectares of land across Australia (and Tasmania). ‘The horse has well and truely bolted’.

The NEMP is suggesting PFAS guidelines of 3 criteria categories with three types of safety margins of 5, 2 and 1. The ranges are from 0.22μg/kg to 31μg/kg for PFOS+PFHxS and 1 to 130μg/kg for PFOA. The current Victorian EPA soil guideline is the sum of 0.004mg/kg (4μg/kg).

From the Tasmanian data it would appear that 22/29 (75.8%) of the treatment plants would breach lower end of NEMP guidelines for PFHxS+PFOS. 2/29 (6.9%) would breach lower end of NEMP for PFOA. The worst offenders being Cambridge Sewerage Treatment Plant, Ranelagh and St Helens with average PFHxS + PFOS levels higher than 31μg/kg. Both Cambridge and Blackmans Bay breached the lower end of the scale for PFOA.

As stated, part of the problem with the NEMP is that it only considers three PFAS chemicals, namely PFOS, PFHxS and PFOA. From the TasWater data, 27/29 (93.1%) would breach lower end of NEMP if all PFAS chemicals were included under NEMP.

Water in Effluent/Influent

Between 2020-2023 TasWater conducted a PFAS investigation at Selfs Point Sewerage Treatment Plant. 62 test regimes occurred at Selfs Point during this time. It is unclear if this investigation targeted influent, effluent or water within the treatment plant. 42% of the tests were positive for PFAS chemicals with very high PFOS levels in April 2020 2,500 times over the 99% ANZECC trigger for PFOS. Between 2021-2023 however the PFOS averages dropped significantly to an average of 0.0135μg/L 1.5 times over the ANZECC 99% trigger level.

Effluent totals from 6 PFAS test regimes from Cambridge Sewerage Treatment Plant in 2023.

The PFHxS samples at Cambridge averaged 0.2125μg/L and the PFOS detections averaged 0.174μg/L, 19 times over the ANZECC 99% trigger level for PFOS. Effluent from Cambridge is released into Sinclair Creek to Pitt Water. Effluent reuse is also sent through to Coal River. TasWater appears to have conducted no tests for PFAS in recycled water throughout Tasmania. Recycled water has been found to contain PFAS in Victoria.

The Pitt Water and Sinclair Creek have been found to contain PFAS chemicals, with the source attributed to Hobart Airport where aqueous film forming foam (AFFF) has been used in the past. TasWater also recently reported that they had a 0% compliance with the 99% NEMP for PFOS at Cambridge STP.


From the small sample size of effluent from 6 TasWater Sewerage Treatment Plants, Western Junction and Ti Tree Bend would breach the ANZECC 99% trigger level for PFOS. ANZECC Guidelines do not yet exist for the two other most frequently detected PFAS chemicals PFHxS and PFHxA or for thousands of other PFAS chemicals.

TasWater information regarding influent coming into treatment plants was very limited. 8 treatment plants (11 sample regimes) recorded influent coming in from outside sources, however the data varies considerably in terms of when samples were taken. Influent at Selfs Point dominated the limited influent data, indicating that PFAS chemicals are entering this plant at levels higher than anywhere else, the source likely to be local sewers. In Victoria, water authorities appear to be taking the issue of influents much more seriously than TasWater. One water authority in western Melbourne is testing PFAS detections in a number of manholes, in order to determine exactly where the PFAS is entering their water treatment plant from.

It was also interesting to note that although Cambridge STP has recorded excessive amounts of PFAS in sludge and effluent, very little appears to be coming in from recorded testing for influent.

The location of Selfs Point Sewerage treatment plant just north of Hobart. Selfs Point is has major inflows of PFAS tainted influent and trade waste.

Trade Waste

Trade waste can come from industrial, commercial and residential properties. Trade waste is sent through to water treatment plants where it is supposedly treated before being released back into the environment as effluent. TasWater do accept PFAS contaminated waste water under Special Approved Waste, although this option does not appear to occur at Selfs Point anymore. PFAS chemicals also do not appear to be listed under the Water and Sewerage Industry (General) Regulations 2019 in Schedule 2 or 3.

Average levels of PFOS and PFHxS coming into Selfs Point over the time period were 3.571μg/L and 0.449μg/L respectively. There was also three positive samples for trade waste from an unstated source in 2017, with all three testing positive for PFOS. The average level of PFOS was 0.307μg/L. It is unclear where the PFAS contaminated Trade Waste from Selfs Point eventually ended up. It is unlikely that treatment would have removed it. It may have ended up in the Derwent River as effluent or ended up as biosolids to be spread over farm land somewhere. It would appear that most would have contained PFAS according to TasWater’s PFAS investigation at Selfs Point Sewerage Treatment Plant.

For more information contact: anthony.amis@foe.org.au