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PFAS Pollution in Groundwater from Victorian Waste Water Treatment Plants

During 2020-2021, Friends of the Earth conducted 15 Freedom of Information Requests (FoI) to Victorian water authorities concerning detections of PFAS in drinking water, water treatment plants, biosolids, recycled water and waste water. This blog only relates to information supplied regarding PFAS detections in groundwater at Waste Water Treatment Plants (WWTP’s) and Recycled Water Plants (RWP’s).  FoE’s first blog in the series on Victorian drinking water can be found here. More background information can be found here.

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Groundwater pollution occurs, when pollutants that have been released to the ground make their way through to groundwater. Wastewater treatment plants have been shown to cause adverse impacts to the surrounding environment and groundwater. Leakage from unlined or partially lined dams and settlement ponds, leaching from biosolids storage areas, use of treated effluent and release of partially treatment effluent can all contribute to pollution in groundwater below the site.

PFAS chemicals make their way into water treatment plants, through use of PFAS in household products (including cleaning, washing and toilet use), industrial waste disposed of in sewers, and landfills (which may also be connected to the sewer system). Once they make their way into WWTP’s, PFAS chemicals can accumulate in biosolids and may only be partially removed during waste water treatment.

Blind Bight Waste Water Treatment Plant (red pin) recorded highest PFAS levels, but 87% of Victorian Water Authorities aren’t testing for PFAS in groundwater. At one bore underlying Blind Bight, a PFOS detection came in at 739 times higher than National Ecological Guidelines levels. The WWTP is in close proximity to the North Western Port Nature Conservation Reserve and RAMSAR listed wetlands. No information could be found determining if PFAS is entering Westernport Bay from the treatment plant.

In terms of groundwater pollution from water treatment plants, the only positive PFAS detections provided via the FOI process pertain to groundwater monitoring of 4 Recycled Water Plants managed by Western Water (now Greater Western Water after a merger with City West Water) and 5 managed by South East Water. The extent of groundwater contamination from waste water treatment plants elsewhere in the state remains unknown as the 13 other water authorities have not tested for it and no other groundwater data was forthcoming via the FOI process.

(Note: A study published in 2018 investigated PFAS contamination of groundwater sourced from recycled water from Melbourne Water's western treatment plant. This water was then used on crops in the Werribee South area. Data from this study was not included in the FoI information supplied by Melbourne Water, as the study was conducted by RMIT. Hence none of the information published in that report has been published in this blog).

Map Key: 1. Bacchus Marsh RWP, 2. Melton RWP, 3. Sunbury RWP, 4. Romsey RWP, 5. Blind Bight WWTP, 6. Boneo WWTP, 7. Mount Martha WWTP, 8. Pakenham WWTP, 9. Somers WWTP. Blue Pin (Altona WTP) Greater Western Water (PFAS has been detected in groundwater at Altona).


From the FoI data, it would appear that testing for PFAS in groundwater at WWTP’s started in 2016 by South East Water at several locations. These included: Blind Bight, Boneo and Koo Wee Rup. Testing was later expanded to Lang Lang, Longwarrry, Mount Martha, Pakenham, Bald Hill Farm (Pakenham) and Somers. Western Water (now known as Great Western Water) started testing for PFAS in groundwater Bacchus Marsh RWP in 2017, Sunbury and Melton in 2018, Woodend, Romsey, Riddells Creek and Gisborne in 2020.

During 2016-21, testing regimes for 28 different PFAS chemicals occurred 48 times in 37 bores/locations managed by Western Water and 189 times in 97 bores managed by South East Water. >1300 individual samples were taken by Western Water, with >5000 individual samples for South East Water.

62.5% of testing regimes found were positive for PFAS at Western Water facilities, with 32.3% positive at South East Water plants. In terms of individual chemical samples, Western Water recorded 101 positives (~7.5% of all samples) and South East Water 230 positives (~4.3% of all samples).

Boneo Waste Water Treatment Facility on the Mornington Peninsula. 85 positive individual PFAS chemicals were detected in groundwater here.

82 bore testing regimes (comprising of 28 different PFAS chemicals), detected PFAS residues. This included 21 positive test regimes at sites managed by Western Water and 61 positive test regimes managed by South East Water.

Melton Recycled Water Plant in close proximity to the Werribee River, where PFAS chemicals were detected 74 times in groundwater. PFAS chemicals have been detected in the Werribee River.

The Western Water positive sampling regimes included Bacchus Marsh (3) + 1 rinsate, Melton (11 from 9 separate bores) + 3 reinsate, Sunbury (1), Romsey (2).

South East Water positive regimes included Bald Farm (1), Blind Bight (34 from 11 separate bores), Boneo (21 from 15 separate bores), Mount Martha (2 from 1 bore), Pakenham (2 from 2 bores), Somers (1).

Western Water PFAS individual positives: Bacchus Marsh 20 positive samples, Sunbury 3 positive samples, Melton 74 positive samples, Romsey 4 positive samples.

South East Water PFAS individual positives: Bald Hill Farm 1 positive sample, Blind Bight 114 positive samples, Boneo 85 positive samples, Mount Martha 17, Pakenham 11, Somers 2

Graph showing how much PFAS has been detected between 2016-21. Blind Bight stands out.

Mount Martha Waste Water Treatment Plant had 17 detections of PFAS in groundwater.

South East Water’s Blind Bight WWTP saw a big increase in PFAS detected in ground water underlying waste water treatment plant over a 5 year period. Most of the PFAS detected at Blind Bight has been detected in one Bore BB08. The FoI provided no information about the exact location or depth of the bores. No information either about how far the PFAS plume/contamination is extending.

10 separate PFAS chemicals have been detected in bore water from BB08 at Blind Bight. Total Sum 6.74 µg/L (May 2021) showed excessive levels of PFHxA 2.6µg/L, PFOA1.4 µg/L*, PFPeA 1.2 µg/L.

* ANZECC 99% Trigger Level PFOA 19µg/L.

PFOS has an ANZECC 99% Trigger Level of 0.00023µg/L. One PFOS level at BB08 breached this guideline in April 2019. That detection was 0.002µg/L or 8.7 times higher than the ANZECC Guideline.

However, Bore BBO7 recorded a PFOS level of 0.17µg/L on May 27 2020. This is 739 times higher than the ANZECC 99% trigger level and higher than the ANZECC 95% trigger level of 0.13µg/L. Seven other bores at Blind Bright were also in breach of the ANZECC 99% PFOS Trigger Level. In fact, the ANZECC 99% PFOS Guideline was breached 17 times at Blind Bight between 2016-2021, with an average PFOS detection level of 0.035µg/L or 152 times higher than the ANZECC 99% Trigger level.

Blind Bight WWTP lies above Zone 6 of the Koo Wee Rup Groundwater Management Unit, within the coastal buffer zone. The Westernport aquifer system generally discharges into Westernport Bay. Blind Bight WWTP also sits above Swamps and Backdune Wetlands, near Westernport Ramsar sites and North Western Port Nature Conservation Reserve.

Across all WWTP’s there were 47 instances where the PFOS 99% Trigger level was breached. The average PFOS level detected at eight WWTP’s where PFOS was detected was 0.031µg/L or close to 135 times above the 99% Trigger level. One detection breached the 95% trigger level.

5. Blind Bight Waste Water Treatment Plant in close proximity to Western Port Nature Conservation Reserve.

Blind Bight WWTP and Melton RWP recorded the most detections of PFOS above ANZECC 99% Trigger level.

Only PFOS and PFOA have trigger levels under the ANZECC Guidelines.

PFHxA had the highest quantity detected in groundwater across the 11 WWTP’s. Average PFHxA detection level in groundwater was 0.239ug/L. The next highest average detection level was for PFPeA 0.112ug/L, followed by PFOA 0.09ug/L, PFHpA 0.07ug/L, PFBA 0.06ug/L, PFHxS 0.04ug/L.

Maximum concentrations for 7 PFAS chemicals all occurred in Groundwater Bore BB08 at Blind Bight (date). PFHxA 2.6ug/L, PFOA 1.4ug/L, PFPeA 1.2ug/L, PFHpA 0.65ug/L, PFHxS 0.35ug/L, PFBA 0.3ug/L, PFBS 0.17ug/L.

Blind Bight groundwater bore BB07 recorded the highest levels of PFOS 0.17ug/L, bore BB04 recorded the highest levels of PFNA 0.007ug/L

Melton RWP recorded the highest levels of FOSA 0.0066ug/L (Bore 12), PFDA 0.0041ug/L (Bore 4), 6:2 FTS 0.14ug/L (Bore 3).

Mount Martha WRP Groundwater Bore 3, recorded the highest levels of PFPeS and EtFOSAA.

PFHxS, PFOA and PFOS were the most commonly detected PFAS chemicals.

The next blog in this series will focus on PFAS contamination from waste water effluent across Victoria.

For more information contact [email protected]

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