Blue Mountains

The NSW Government has advised Sydney's drinking water is compliant with Australian Drinking Water Guidelines and is safe to drink.

In June 2025 the National Health and Medical Research Council (NHMRC) released updated Australian Drinking Water guidelines which outline new, lower recommended values of PFAS in drinking water.

Learn more at nsw.gov.au/pfas

Related pages: PFAS | Greater Sydney | Fish River scheme | Regional NSW

Investigation

WaterNSW has completed its initial investigation into the source of PFAS contamination in the Adams Creek and Medlow catchments. The findings have been reviewed by the NSW PFAS Technical Advisory Group and the NSW Environment Protection Authority (EPA) and they concur with the findings. WaterNSW is commencing further detailed investigations with support from the EPA, to refine potential source identification and appropriate management actions.

Investigation of the Blue Mountains dams and catchment commenced in July 2024, 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.

The investigation included rigorous testing of water sources in the Blue Mountains ’ catchment, including soil and water sampling, among a number of other steps. It also examined potential historical use of fire retardant in the catchment, including in earlier vehicle accidents and bushfires.

Three potential sources of contamination have been identified - two separate motor vehicle accident sites on the Great Western Highway (in 1992 and 2002) near the Medlow Bath township and the Medlow Bath Rural Fire Brigade station. The chemical compound signature identified is consistent with that used in Aqueous Fire Fighting Foam (AFFF). While firefighting foam has historically been identified as a source of PFAS in the environment, it has also been confirmed that low-level PFAS contamination is present throughout the environment, with detections at various concentrations in the catchment.

Initial findings indicate PFAS concentrations are higher in the upper Adams Creek catchment than further downstream in the Medlow/Greaves catchment. This suggests that any contamination from the potential sources identified in the investigation may be moving downstream into the Medlow/Greaves catchment via rainfall and surface water runoff, and previous water transfers between dams.

Read the technical memo (PDF, 29373.47 KB)

Read the advice to WaterNSW from the Environment Protection Authority (PDF, 194.73 KB)

Next steps

The EPA has recommended that a detailed site investigation should now be undertaken consistent with the National Environment Protection Measure 1999. The outcomes will help inform potential remediation options.

Detailed investigations are likely to involve a number of agencies, with support from the NSW EPA.

Medlow Dam and Greaves Creek Dam, of which Adams Creek is a tributary, will remain disconnected from the Blue Mountains water supply system. The dams will only be returned to the raw water supply network once we are confident appropriate permanent mitigation measures are in place.

Separately, Sydney Water installed a new treatment system at the Cascade Water Filtration Plant which has been operating since January 2025. Read more about this on Sydney Water’s website.

WaterNSW will continue to publish raw water monitoring data from the Blue Mountains storage dams.

Learn more about the WaterNSW investigation and findings

The WaterNSW investigation enlisted independent specialist advice and included an extensive sampling program, with more than 250 samples taken in 37 different locations.

All accessible tributaries and streams within the watershed of the Great Western Highway were tested.

Sediment samples were collected from Medlow dam and numerous creek beds.

Based on expert advice, surface water (water in creeks and dam reservoirs) was prioritised during the investigation as a more significant way for chemicals to move throughout the catchment.

An evaluation of sewerage and stormwater drainage pathways and a conceptual site model were also developed to understand how contaminants may move throughout the catchment.

An analysis of Rural Fire Service, Fire and Rescue NSW and Transport for NSW records related to historic activities in the area was also conducted.

The investigation also examined potential use of fire retardant in the catchment during earlier bushfires.

Community updates

Community update (May 2025)
Blue Mountains community update | May 2025 (PDF, 231.62 KB)

Community update (March 2025)
Blue Mountains community update | March 2025 (PDF, 746.57 KB)

Community update (December 2024)
Blue Mountains community update | December 2024 (PDF, 224.46 KB)

Community update (September 2024)
Blue Mountains catchment | PFAS investigation update (PDF, 497.06 KB)

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.

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.

View Blue Mountains system graphic >

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.

View indicative sample map >

Water monitoring data results

Results are published monthly. Medlow Dam and Greaves Creek Dam remain disconnected from supply.

June 2025 sampling - 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	Sample date	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)	PFBS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	11/6/2025	<0.0005	0.0199	0.0266	0.0465	0.0038
Greaves Creek Dam (1m depth) Disconnected from supply	25/6/2025	0.0009	0.0193	0.0281	0.0474	0.0034
Medlow Dam (1m depth) Disconnected from supply	11/6/2025	0.0007	0.0321	0.0493	0.0814	0.0055
Medlow Dam (1m depth) Disconnected from supply	25/6/2025	0.0013	0.0292	0.0452	0.0744	0.0048
Upper Cascade Dam (1m depth)	11/6/2025	<0.0005	0.0022	0.0041	0.0032	0.0005
Upper Cascade Dam (1m depth)	25/6/2025	<0.0005	0.0022	0.0032	0.0054	0.0005
Source water inlet to Cascade water filtration plant	11/6/2025	Site visited, water filtration plant was offline.
Source water inlet to Cascade water filtration plant	25/6/2025	<0.0005	0.0017	0.0026	0.0043	<0.0005
Raw water Oberon pipeline to Cascades at Leura	Pipeline offline during June.

May 2025 sampling - Raw (untreated) water

For drinking water results, please visit Sydney Water.

Water source	Sample date	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	14/5/2025	0.0012	0.0338	0.0438	0.0776
Greaves Creek Dam (1m depth) Disconnected from supply	28/5/2025	0.0009	0.0224	0.0331	0.0555
Medlow Dam (1m depth) Disconnected from supply	14/5/2025	0.0017	0.0465	0.0600	0.1060
Medlow Dam (1m depth) Disconnected from supply	28/5/2025	0.0012	0.0282	0.0463	0.0745
Upper Cascade Dam (1m depth)	14/5/2025	<0.0005	0.0028	0.0043	0.0071
Upper Cascade Dam (1m depth)	28/5/2025	<0.0005	0.0025	0.0047	0.0071
Source water inlet to Cascade water filtration plant	14/5/2025	<0.0005	0.0026	0.0047	0.0073
Source water inlet to Cascade water filtration plant	28/5/2025	<0.0005	0.0028	0.0045	0.0073
Raw water Oberon pipeline to Cascades at Leura	Pipeline offline at time of sampling.

April 2025 sampling - Raw (untreated) water

For drinking water results, please visit Sydney Water.

Water source	Sample date	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	2/4/2025	0.0012	0.0351	0.0392	0.0743
Greaves Creek Dam (1m depth) Disconnected from supply	16/4/2025	0.0011	0.0331	0.0403	0.0734
Greaves Creek Dam (1m depth) Disconnected from supply	30/4/2025	0.0013	0.0343	0.0406	0.0749
Medlow Dam (1m depth) Disconnected from supply	2/4/2025	0.0017	0.0510	0.0591	0.1100
Medlow Dam (1m depth) Disconnected from supply	16/4/2025	0.0017	0.0531	0.0605	0.1140
Medlow Dam (1m depth) Disconnected from supply	30/4/2025	0.0016	0.0552	0.0643	0.1200
Upper Cascade Dam (1m depth)	2/4/2025	<0.0005	0.0041	0.0044	0.0085
Upper Cascade Dam (1m depth)	16/4/2025	<0.0005	0.0033	0.0046	0.0079
Upper Cascade Dam (1m depth)	30/4/2025	<0.0005	0.0034	0.0042	0.0076
Source water inlet to Cascade water filtration plant	2/4/2025	<0.0005	0.0041	0.0044	0.0085
Source water inlet to Cascade water filtration plant	16/4/2025	<0.0005	0.0038	0.0034	0.0072
Source water inlet to Cascade water filtration plant	30/4/2025	<0.0005	0.0030	0.0041	0.0071
Raw water Oberon pipeline to Cascades at Leura	2/4/2025	<0.0005	<0.0005	<0.0003	<0.0003

March 2025 sampling - Raw (untreated) water

For drinking water results, please visit Sydney Water.

Water source	Sample date	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	19/03/2025	0.0011	0.0332	0.0391	0.0723
Greaves Creek Dam (1m depth) Disconnected from supply	05/03/2025	0.0013	0.0335	0.0439	0.0774
Medlow Dam (1m depth) Disconnected from supply	19/03/2025	0.0019	0.0492	0.0546	0.104
Medlow Dam (1m depth) Disconnected from supply	05/03/2025	0.0019	0.0507	0.0692	0.12
Upper Cascade Dam (1m depth)	19/03/2025	<0.0005	0.0032	0.0039	0.0071
Upper Cascade Dam (1m depth)	05/03/2025	<0.0005	0.0043	0.0054	0.0097
Middle Cascade (1m depth)	No longer routinely sampled due to its location between Upper and Lower Cascades sample sites.
Lower Cascade (1m depth) Now sampled bi-monthly	05/03/2025	<0.0005	0.0028	0.0038	0.0066
Source water inlet to Cascade water filtration plant	19/03/2025	<0.0005	0.003	0.0038	0.0068
Source water inlet to Cascade water filtration plant	05/03/2025	<0.0005	0.0042	0.0054	0.0096
Raw water Oberon pipeline to Cascades at Leura Now sampled monthly	05/03/2025	<0.0005	<0.0005	<0.0003	<0.0003

February 2025 sampling – Raw (untreated) water

For drinking water results, please visit Sydney Water.

Results of samples taken 19 February 2025 – Raw (untreated) water

Water source	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	0.0017	0.0346	0.0442	0.0788
Medlow Dam (1m depth) Disconnected from supply	0.0022	0.0497	0.0655	0.115
Upper Cascade Dam (1m depth)	<0.0005	0.0044	0.0058	0.0102
Middle Cascade (1m depth)	<0.0005	0.0042	0.0064	0.0106
Lower Cascade (1m depth)	<0.0005	0.0027	0.0049	0.0076
Source water inlet to Cascade water filtration plant	<0.0005	0.0036	0.0068	0.0104
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

Results of samples taken 5 February 2025 – Raw (untreated) water

Water source	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	0.0011	0.0296	0.0415	0.0711
Medlow Dam (1m depth) Disconnected from supply	0.0014	0.0468	0.0521	0.0989
Upper Cascade Dam (1m depth)	<0.0005	0.004	0.0053	0.0093
Middle Cascade (1m depth)	<0.0005	0.0038	0.0052	0.009
Lower Cascade (1m depth)	Unable to be accessed for sampling on 5/2/25.
Source water inlet to Cascade water filtration plant	<0.0005	0.0039	0.0055	0.0094
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

January 2025 sampling – Raw (untreated) water

For drinking water results, please visit Sydney Water.

Results of samples taken 22 January 2025 – Raw (untreated) water

Water source	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	0.0015	0.0304	0.0423	0.0727
Medlow Dam (1m depth) Disconnected from supply	0.002	0.041	0.0637	0.105
Upper Cascade Dam (1m depth)	<0.0005	0.0041	0.0058	0.0099
Middle Cascade (1m depth)	<0.0005	0.0038	0.0057	0.0095
Lower Cascade (1m depth)	Unable to be accessed for sampling on 22/1/25.
Source water inlet to Cascade water filtration plant	<0.0005	0.0044	0.0061	0.0105
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

Results of samples taken 8 January 2025 – Raw (untreated) water

Water source	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	0.0014	0.0358	0.0499	0.0857
Medlow Dam (1m depth) Disconnected from supply	0.0019	0.051	0.0771	0.128
Upper Cascade Dam (1m depth)	<0.0005	0.0058	0.009	0.0148
Middle Cascade (1m depth)	<0.0005	0.005	0.0081	0.0131
Lower Cascade (1m depth)	<0.0005	0.003	0.0042	0.0072
Source water inlet to Cascade water filtration plant	<0.0005	0.0061	0.0082	0.0143
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

December 2024 sampling – Raw (untreated) water

Results of samples taken 18 December 2024 – Raw (untreated) water

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) Disconnected from supply	0.0015	0.0438	0.0436	0.0874
Medlow Dam (1m depth) Disconnected from supply	0.0024	0.0693	0.0661	0.135
Upper Cascade Dam (1m depth)	<0.0005	0.0072	0.0079	0.0151
Middle Cascade (1m depth)	<0.0005	0.0063	0.0075	0.0138
Lower Cascade (1m depth)	<0.0005	0.0037	0.0034	0.0071
Source water inlet to Cascade water filtration plant	<0.0005	0.0069	0.0077	0.0146
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

Results of samples taken 2 December 2024 – Raw (untreated) water

Water source	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	0.0012	0.0416	0.0488	0.0904
Medlow Dam (1m depth) Disconnected from supply	0.0026	0.0673	0.0824	0.15
Upper Cascade Dam (1m depth)	<0.0005	0.0071	0.009	0.0161
Middle Cascade (1m depth)	<0.0005	0.0036	0.0037	0.0073
Lower Cascade (1m depth)	<0.0005	0.0029	0.0029	0.0058
Source water inlet to Cascade water filtration plant	<0.0005	0.0066	0.0085	0.0151
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

November 2024 sampling – Raw (untreated) water

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

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) Disconnected from supply	0.0011	0.0262	0.0363	0.0625
Medlow Dam (1m depth) Disconnected from supply	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

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) Disconnected from supply	0.001	0.0271	0.0437	0.0708
Medlow Dam (1m depth) Disconnected from supply	0.0019	0.0529	0.0729	0.126
Upper Cascade Dam (1m depth)	<0.0005	0.0078	0.0115	0.0193
Middle Cascade (1m depth)	<0.0005	0.0033	0.0042	0.0075
Lower Cascade (1m depth)	<0.0005	0.0025	0.0033	0.0058
Source water inlet to Cascade water filtration plant	<0.0005	0.0074	0.0113	0.0187
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

October 2024 sampling – Raw (untreated) water

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

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) Disconnected from supply	0.001	0.0283	0.0393	0.0676
Medlow Dam (1m depth) Disconnected from supply	0.0018	0.047	0.0669	0.114
Upper Cascade Dam (1m depth)	<0.0005	0.0073	0.0098	0.0171
Middle Cascade (1m depth)	<0.0005	0.0034	0.0055	0.0089
Lower Cascade (1m depth)	<0.0005	0.0024	0.003	0.0054
Source water inlet to Cascade water filtration plant	<0.0005	0.0075	0.0098	0.0173
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

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) Disconnected from supply	0.0009	0.0265	0.0409	0.0674
Medlow Dam (1m depth) Disconnected from supply	0.0019	0.0605	0.0602	0.121
Upper Cascade Dam (1m depth)	<0.0005	0.0087	0.0101	0.0188
Middle Cascade (1m depth)	<0.0005	0.0029	0.0037	0.0066
Lower Cascade (1m depth)	<0.0005	0.0022	0.003	0.0052
Raw water Oberon pipeline to Cascades at Leura	<0.0005	<0.0005	<0.0003	<0.0003

September 2024 sampling – Raw (untreated) water

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 source	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	0.0009	0.0319	0.0351	0.0670
Medlow Dam (1m depth) Disconnected from supply	0.0014	0.0450	0.0690	0.114
Upper Cascade Dam (1m depth)	<0.0005	0.0098	0.0136	0.0234
Middle Cascade (1m depth)	<0.0005	0.0034	0.0046	0.0080
Lower Cascade (1m depth)	<0.0005	0.0025	0.0034	0.0059

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

For drinking water results, please visit Sydney Water.

Water source	Sample date	PFOA (µg/L)	PFHxS (µg/L)	PFOS (µg/L)	PFHxS + PFOS (µg/L)
Greaves Creek Dam (1m depth) Disconnected from supply	10/9/24	0.0008	0.0229	0.0291	0.0520
Medlow Dam (1m depth) Disconnected from supply	18/9/24	0.0016	0.0524	0.0614	0.114
Upper Cascade Dam (1m depth)	17/9/24	<0.0005	0.008	0.0125	0.0205
Middle Cascade (1m depth)	18/9/24	<0.0005	0.0050	0.0053	0.0103
Lower Cascade (1m depth)	10/9/24	<0.0005	0.0023	0.0026	0.0049
Raw water supplied to Cascade water filtration plant	17/9/24	<0.0005	0.0082	0.0122	0.0204
Raw water from Oberon Dam supplied to Duckmaloi water filtration plant	19/9/24	<0.0005	<0.0005	0.0006	0.0006

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

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) Disconnected from supply	0.0009	0.0264	0.0324	0.0588
Medlow Dam (1m depth) Disconnected from supply	0.0017	0.0485	0.0608	0.109
Upper Cascade Dam (1m depth)	<0.0005	0.0098	0.0127	0.0225
Middle Cascade (surface)	<0.0005	0.0051	0.0402	0.0453
Lower Cascade (1m depth)	<0.0005	0.0023	0.0027	0.005
Raw water supplied to Cascade water filtration plant	<0.0005	0.0113	0.0124	0.0237

August 2024 sampling – Raw (untreated) water

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

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 (surface) Disconnected from supply	0.001	0.0275	0.0315	0.059
Medlow Dam (surface) Disconnected from supply	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	0.0006	0.0006

July 2024 sampling – Raw (untreated) water

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

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 (surface)	0.0009	0.0244	0.0335	0.0579
Medlow Dam (surface)	0.0014	0.0398	0.0548	0.0946
Upper Cascade Dam (surface)	0.0005	0.0098	0.014	0.0238
Lower Cascade Dam (surface)	<0.0005	0.0019	0.003	0.0049
Raw water supplied to Cascade water filtration plant	<0.0005	0.0109	0.0136	0.0245
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?

The NSW Government has advised Sydney’s drinking water is compliant with Australian Drinking Water Guidelines and is safe to drink. For NSW Government information on PFAS visit nsw.gov.au/pfas.

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.

All samples are subject to quality control and assurances processes. Should any part of the process not meet these requirements, results are not considered valid and are not reported on our website.

How often are results for PFAS testing in WaterNSW dams published? Where can I read them?

Results are published monthly for the Blue Mountains and Greater Sydney. Results of testing in our regional NSW dams and Fish River Scheme are published quarterly. 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.

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 bush fires) to manage water quality.

Has WaterNSW transferred any additional water from Oberon Dam to the Blue Mountains dams?

Yes, transfers commenced 30 September 2024.

Get in touch

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

Blue Mountains

The NSW Government has advised Sydney's drinking water is compliant with Australian Drinking Water Guidelines and is safe to drink.

Investigation

Next steps

Community updates

What is the Blue Mountains system?

Results

Medlow Dam and Greaves Creek Dam

Adams Creek

Water monitoring data results

Frequently asked questions

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