Blue Mountains

PFAS investigation and raw water testing results

Sydney Water and NSW Health have advised Sydney's drinking water is compliant with the existing Australian Drinking Water Guidelines and is safe to drink.

On Monday 21 October 2024, the National Health and Medical Research Centre (NHMRC) released proposed guidelines which outline new and lower recommended trigger values of PFAS in our drinking water. Importantly, the NHMRC has confirmed that our drinking water remains safe to drink while it meets existing drinking water guidelines.

Learn more at nsw.gov.au/pfas


Related pages:  PFAS |  Greater Sydney PFAS results | Fish River scheme PFAS results

Investigation

WaterNSW is conducting targeted PFAS-related investigations, so any risks continue to be managed appropriately.

Investigations include rigorous testing of water sources in the Blue Mountains’ catchment – including soil and water sampling – to investigate the source and causes of the elevated PFAS results. The extensive WaterNSW sampling program is occurring alongside work with multiple NSW Government agencies to explore other historical land use activities that potentially involved PFAS, such as firefighting.

Investigation of the Blue Mountains dams and catchment commenced in July, following Sydney Water testing which detected PFAS at levels below the Australian Drinking Water Guidelines at the Cascade water filtration plant.

Early water quality results indicated Medlow Dam is impacted by elevated levels of PFAS. WaterNSW disconnected Medlow Dam and Greaves Creek Dam from supply as a precautionary measure while investigations continue. The outcome of the investigation will inform the next steps WaterNSW will take to further mitigate risk.

Jump to section: What is being done?

What is the Blue Mountains system?

The Blue Mountains system sources water from within and outside the Blue Mountains catchments. These catchments are a small group of bushland valleys that feed water to Medlow Dam, Greaves Creek Dam and the Upper, Middle and Lower Cascade dams. The configuration of the Blue Mountains system is flexible, allowing us to take dams on and offline as needed to help us meet demand. The dams are all inaccessible to the public.

These five dams provide water for Sydney Water's Cascade water filtration plant at Katoomba, which supplies drinking water to the middle and upper Blue Mountains.

Supplies can be topped up when needed with water from Oberon Dam via a pipeline from the Fish River Scheme, west of the Great Dividing Range at Oberon.

What is being done?

PFAS contamination investigations are complex, due to the long-lasting nature of PFAS in the environment. This means that our investigation covers the entire Blue Mountains water supply catchment and is drawing on information spanning a number of decades.

WaterNSW’s investigations are focused on identifying the source of the PFAS contamination in the Blue Mountains catchment. The investigation has a number of phases with initial broad sampling throughout both the Cascades and Medlow sub-catchments informing more detailed investigations.

We have engaged an independent contaminated site consultant with specialised experience in PFAS investigations. These detailed investigations will take a number of months.

These investigations involve:

  • Monitoring and testing soil and water throughout the catchment
    We are undertaking rigorous testing of water sources and soil in the Blue Mountains catchment, with more than 100 samples from 30 sites, including water testing at various depths in the Blue Mountains dams.

  • Ensuring correct sampling collection, transport and analysis
    Sampling, collection and transport are conducted by highly-skilled professionals with strict protocols in place. Our partner labs have detailed steps that must be followed to ensure accurate analysis of our samples. This is essential to ensure that samples are not contaminated by everyday items that contain PFAS such as outdoor clothing, makeup, and sunscreen. Our monitoring teams are ISO 9001 certified, and all partner laboratories are NATA accredited.

  • Mapping land use across the catchment to help identify the potential source or cause of contaminants.

  • Investigating fire and firefighting history
    WaterNSW is working with multiple government organisations including Rural Fire Service and NSW Fire and Rescue to explore historical land use including potential activities where PFAS has been used, such as firefighting activities.

  • Tracing drainage pathways through the catchment, such as sewerage and stormwater.

  • Engaging a contaminated site investigation specialist to provide tailored advice and ensure every avenue of enquiry is explored.

  • Developing a conceptual site model to understand the ways that contaminants may move from sources in the soil and water through the catchment, helping target sampling and evaluate options for mitigation. The conceptual site model will inform a detailed site investigation which will provide information on short-to long term management strategies and remediation options.

Exact timings for the investigation outcomes will be influenced by developments of the investigation into the nature and extent of the contamination, but we anticipate a report to be available in mid-2025.

In the meantime, Medlow and Greaves Creek dams remain disconnected from the water supply system.

What might remediation involve?

Once the nature and extent of contamination is suitably characterised, a detailed remediation action plan will be prepared. Options may include disposal of contaminated materials or containment.

When will information be made available regarding the investigation?

We will continue to publish raw water monitoring data from the Blue Mountains dams monthly. We anticipate a report to be made available in mid-2025.

Have you ever closed dams like this before?

We take dams offline for operational reasons routinely as required.

We modify system configuration often in Greater Sydney for various reasons. WaterNSW dams can be isolated for maintenance and that is what makes the system quite resilient and flexible, allowing us to maintain water supply as conditions change.

For example, we’ve taken Warragamba Dam offline during large inflow events (or bushfires) to manage water quality.

Results

Medlow Dam and Greaves Creek Dam

Early water quality results indicated Medlow Dam is impacted by elevated levels of PFAS. WaterNSW disconnected Medlow Dam and Greaves Creek Dam from supply as a precautionary measure while investigations continue. The outcome of the investigation will inform the next steps WaterNSW will take to further mitigate risk.

A simplified overview of the Blue Mountains dam network.


Adams Creek

Catchment testing has highlighted a small creek in the upper reaches of the Medlow catchment that flows into the dam, Adams Creek, as an area for targeted investigations.

Indicative sample collection sites - current and planned

A map showing the creeks that flow into Medlow Dam and Greaves Creek Dam, with pin locations where samples have been collected for testing.



Water monitoring data results

Results will be published monthly. The next round of results is expected to be published mid-January 2025.

Results of samples taken 20 November 2024 – Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water but is supplied to Sydney Water for treatment at the Cascades Water Filtration Plant.

For drinking water results, please visit Sydney Water.

Water source PFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (1m depth) 0.0011 0.0262 0.0363 0.0625
Medlow Dam (1m depth) 0.0019 0.0481 0.0627 0.111
Upper Cascade Dam (1m depth) <0.0005 0.0066 0.0089 0.0155
Middle Cascade (1m depth) <0.0005 0.0027 0.0033 0.006
Lower Cascade (1m depth) <0.0005 0.0026 0.0031 0.0057
Source water inlet to Cascade water filtration plant <0.0005 0.0071 0.0093 0.0164
Raw water Oberon pipeline to Cascades at Leura <0.0005 <0.0005 0.0004 0.0004

Results of samples taken 6 November 2024 – Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water but is supplied to Sydney Water for treatment at the Cascades Water Filtration Plant.

For drinking water results, please visit Sydney Water.

Water source PFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (1m depth)0.0010.02710.04370.0708
Medlow Dam (1m depth)0.00190.05290.07290.126
Upper Cascade Dam (1m depth)<0.00050.00780.01150.0193
Middle Cascade (1m depth)<0.00050.00330.00420.0075
Lower Cascade (1m depth)<0.00050.00250.00330.0058
Source water inlet to Cascade water filtration plant<0.00050.00740.01130.0187
Raw water Oberon pipeline to Cascades at Leura<0.0005<0.0005<0.0003<0.0003

Results of samples taken 23 October 2024 – Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water but is supplied to Sydney Water for treatment at the Cascades Water Filtration Plant.

For drinking water results, please visit Sydney Water.

Water sourcePFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (1m depth)0.0010.02830.03930.0676
Medlow Dam (1m depth)0.00180.0470.06690.114
Upper Cascade Dam (1m depth)<0.00050.00730.00980.0171
Middle Cascade (1m depth)<0.00050.00340.00550.0089
Lower Cascade (1m depth)<0.00050.00240.0030.0054
Source water inlet to Cascade water filtration plant<0.00050.00750.00980.0173
Raw water Oberon pipeline to Cascades at Leura<0.0005<0.0005<0.0003<0.0003

Results of samples taken 9 October 2024 – Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water but is supplied to Sydney Water for treatment at the Cascades Water Filtration Plant.

For drinking water results, please visit Sydney Water.

Water sourcePFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (1m depth)0.00090.02650.04090.0674
Medlow Dam (1m depth)0.00190.06050.06020.121
Upper Cascade Dam (1m depth)<0.00050.00870.01010.0188
Middle Cascade (1m depth)<0.00050.00290.00370.0066
Lower Cascade (1m depth)<0.00050.00220.0030.0052
Raw water Oberon pipeline to Cascades at Leura<0.0005<0.0005<0.0003<0.0003

Results of samples taken 27 September 2024 – Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water, but is supplied to Sydney Water for treatment at the Cascades Water Filtration Plant.

For drinking water results, please visit Sydney Water.

Water sourcePFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (1m depth)0.00090.03190.03510.0670
Medlow Dam (1m depth)0.00140.04500.06900.114
Upper Cascade Dam (1m depth)<0.00050.00980.01360.0234
Middle Cascade (1m depth)<0.00050.00340.00460.0080
Lower Cascade (1m depth)<0.00050.00250.00340.0059

Results of samples taken 10 and 17-19 September 2024 – Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water, but is supplied to Sydney Water for treatment at the Cascades Water Filtration Plant.

For drinking water results, please visit Sydney Water.

Water sourceSample datePFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (1m depth)10/9/240.00080.02290.02910.0520
Medlow Dam (1m depth)18/9/240.00160.05240.06140.114
Upper Cascade Dam (1m depth)17/9/24<0.00050.0080.01250.0205
Middle Cascade (1m depth)18/9/24<0.00050.00500.00530.0103
Lower Cascade (1m depth)10/9/24<0.00050.00230.00260.0049
Raw water supplied to Cascade water filtration plant17/9/24<0.00050.00820.01220.0204
Raw water from Oberon Dam supplied to Duckmaloi water filtration plant19/9/24<0.0005<0.00050.00060.0006

Results of samples taken 3 September 2024 - Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water, but is supplied to Sydney Water for treatment at the Cascades water treatment plant.

For drinking water results, please visit Sydney Water.

Water sourcePFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (1m depth)0.00090.02640.03240.0588
Medlow Dam (1m depth)0.00170.04850.06080.109
Upper Cascade Dam (1m depth)<0.00050.00980.01270.0225
Middle Cascade (surface)<0.00050.00510.04020.0453
Lower Cascade (1m depth)<0.00050.00230.00270.005
Raw water supplied to Cascade water filtration plant<0.00050.01130.01240.0237

Results of samples taken 16 August 2024 - Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water, but is supplied to Sydney Water for treatment at the Cascades water treatment plant.

For drinking water results, please visit Sydney Water.

Water sourcePFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (surface) 0.001 0.0275 0.0315 0.059
Medlow Dam (surface) 0.0015 0.0456 0.0488 0.0944
Upper Cascade Dam (surface) <0.0005 0.0098 0.0272 0.037
Middle Cascade (surface) <0.0005 0.0035 0.0042 0.0077
Lower Cascade (surface) <0.0005 0.002 0.0022 0.0042
Raw water supplied to Cascade water filtration plant <0.0005 0.0092 0.0111 0.0203
Raw water from Oberon Dam supplied to Duckmaloi water filtration plant <0.0005 <0.0005 0.00060.0006

Results of samples taken 31 July 2024 - Raw (untreated) water

These results reflect the untreated, raw source water in WaterNSW’s dams. This water is not supplied directly for use as drinking water, but is supplied to Sydney Water for treatment at the Cascades water treatment plant.

For drinking water results, please visit Sydney Water.

Water sourcePFOA
(µg/L)
PFHxS
(µg/L)
PFOS
(µg/L)
PFHxS + PFOS
(µg/L)
Greaves Creek Dam (surface) 0.0009 0.0244 0.03350.0579
Medlow Dam (surface) 0.0014 0.0398 0.0548 0.0946
Upper Cascade Dam (surface)0.0005 0.0098 0.0140.0238
Lower Cascade Dam (surface)<0.0005 0.00190.0030.0049
Raw water supplied to Cascade water filtration plant<0.0005  0.01090.01360.0245
Raw water from Oberon Dam supplied to Duckmaloi water filtration plant <0.0005 <0.0005 <0.0003<0.0008

Frequently asked questions

Is Sydney’s water safe to drink?

Sydney Water and NSW Health have advised Sydney’s drinking water is compliant with the existing Australian Drinking Water Guidelines (ADWG) and is safe to drink. For NSW Government information on PFAS visit www.nsw.gov.au/pfas.

For most people, drinking water is sourced from well-protected, often pristine catchments, and water goes through multiple levels of testing to ensure it is safe and meets the Australian Drinking Water Guidelines.

WaterNSW supplies untreated water, sometimes described as 'raw water' or 'source water', to Sydney Water and councils around NSW who then treat and supply the water to your tap. The Fish River Water Supply System is an exception. This process of testing and treating the ‘source water’ we supply is rigorous, ensuring that drinking water that comes out of your tap is safe and meets the Australian Drinking Water Guidelines.

The thorough scientific process for setting the guidelines helps maintain high quality drinking water for all Australians. Australia has some of the highest quality drinking water compared to anywhere else in the world.

How is the Sydney drinking water catchment monitored?

Sydney’s drinking water catchment is 16,000 square kilometres – about half the size of Belgium.

Water quality monitoring across the catchment follows a targeted, risk-based approach to help ensure the treated water supplied for consumption meets the existing Australian Drinking Water Guidelines. Consistent with the government regulatory frameworks, the approach is based on expert advice from NSW Health and other authorities such as the Environment Protection Authority.

Does WaterNSW test for PFAS?

WaterNSW monitors many water quality parameters over a very large area across the Greater Sydney catchment and dams. This includes extensive water testing and real time monitoring 24/7. Each month thousands of data points are collected and evaluated continually for the management of source water quality.

When testing for PFAS, WaterNSW takes a targeted, risk-based approach, based on based on expert advice from NSW Health and other authorities such as the Environment Protection Authority.

How do you sample and test?

WaterNSW has highly-experienced field staff and expert water quality scientists undertaking sampling and analysis.

Sampling, collection and transport are conducted by highly-skilled professionals with strict protocols in place. Our partner labs have detailed steps that must be followed to ensure accurate analysis of our samples. This is essential to ensure that samples are not contaminated by everyday items that contain PFAS such as outdoor clothing, makeup, and sunscreen. Our monitoring teams are ISO 9001 certified, and all partner laboratories are NATA accredited.

WaterNSW is a highly regulated organisation and subject to extensive external regulatory oversight. This ensures WaterNSW’s work in this field is meticulous and meets the highest standard. WaterNSW has an extensive water quality monitoring program and is one of the leading agencies when it comes to water quality monitoring in NSW.

How often will you be carrying out PFAS testing in WaterNSW dams?

WaterNSW is carrying out fortnightly testing of the Blue Mountains System, and monthly testing of Greater Sydney storage dams.  Results are published monthly. Water goes through multiple levels of testing and treatment to ensure it is safe and meets the Australian Drinking Water Guidelines before it comes out of your taps.

How is WaterNSW communicating the results of its testing?

The results of the testing are available here on our website. Dedicated pages have been created for Blue Mountains System and Greater Sydney storage dam results. Result data is published monthly.

Why are different depths tested and reported?

We test at different depths and consistently measure and report at the offtake depth, to be representative of the raw water being supplied via our pipelines to the various water filtration plants.  We are working to consistently measure and report the most accurate and useful data with Sydney Water and NSW Health and to keep the community informed.

How Is WaterNSW responding to the proposed new drinking water guidelines?

WaterNSW will work with the NSW Government on implementation of the revised guideline levels as required.

Get in touch

Questions can be submitted to our team at engagement@waternsw.com.au.

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