Yass Water Supply – Monitoring for PFAS/PFOS
Updated 8 July 2026
PFAS (per-and poly-fluoroalkyl substances) are a family of chemicals that have been used widely in industrial and consumer products since the 1950s. They are persistent in the environment and sometimes referred to as 'forever chemicals'. Australian Drinking Water Guidelines (ADWG) endorsed specific limits in June 2025 as summarised below.
| Parameter |
ADWG health-based guideline values, June 2025 |
| Perfluorooctane sulfonic acid (PFOS) |
8 nanograms per litre |
(0.008µg/L) |
| Perfluorooctanoic acid (PFOA) |
200 nanograms per litre |
(0.200µg/L) |
| Perfluorohexane sulfonic acid (PFHxS) |
30 nanograms per litre |
(0.030µg/L) |
| Perfluorobutane sulfonic acid (PFBS) |
1000 nanograms per litre |
(1.000µg/L) |
For more information please see PFAS Fact Sheet(PDF, 221KB).
Additional information can be found here.
Prior to June 2025, limits were specified for perfluorooctane sulphonate (PFOS), perfluorohexane sulphonate (PFHxS), and perfluorooctanoic acid (PFOA).
Council conducted monitoring of PFAS for the Yass Water Supply in July 2024 and in June 2025 with the support of NSW Health. Monitoring in June 2026 is follow-up by Council. Drinking water samples supplied from the Yass Water Supply System were analysed at the Sydney Water Laboratory Services.
Results to date are summarised below.
Yass Water Supply - Treated water from WTP 2026
|
Date of Sample
|
Parameter
|
ADWG health-based Guideline Values June 2025
|
Value
|
Unit
|
Yass WTP Treated Water T17
|
Remarks
|
|
18-Jun-26
|
Perfluorooctane sulfonic acid (PFOS)
|
8 nanograms per litre
|
0.008
|
µg/L
|
0.0006
|
Below ADWG limits
|
|
18-Jun-26
|
Perfluorooctanoic acid (PFOA)
|
200 nanograms per litre
|
0.200
|
µg/L
|
0.0003
|
Below ADWG limits
|
|
18-Jun-26
|
Perfluorohexane sulfonic acid (PFHxS)
|
30 nanograms per litre
|
0.03
|
µg/L
|
0.0010
|
Below ADWG limits
|
|
18-Jun-26
|
Perfluorobutane sulfonic acid (PFBS)
|
1000 nanograms per litre
|
1.000
|
µg/L
|
0.0006
|
Below ADWG limits
|
Yass Water Supply - Treated water from WTP 2025
| Date of Sample |
Parameter |
ADWG health-based Values June 2025
|
Value |
Unit |
Yass WTP Treated Water T17
|
Remarks |
| 23-Jun-25 |
Perfluorooctane sulfonic acid (PFOS)
|
8 nanograms per litre |
0.008 |
µg/L |
<0.0001 |
Below ADWG limits |
| 23-Jun-25 |
Perfluorooctanoic acid (PFOA)
|
200 nanograms per litre |
0.200 |
µg/L |
0.0002 |
Below ADWG limits |
| 23-Jun-25 |
Perfluorohexane sulfonic acid (PFHxS)
|
30 nanograms per litre |
0.03 |
µg/L |
0.0009 |
Below ADWG limits |
| 23-Jun-25 |
Perfluorobutane sulfonic acid (PFBS)
|
1000 nanograms per litre |
1.000 |
µg/L |
<0.0005 |
Below ADWG limits |
Yass Water Supply - Old Quarry Bore Water 2026
|
Date of Sample
|
Parameter
|
ADWG health-based Guideline values June 2025
|
Value
|
Unit
|
Old Quarry Bore Water T18
|
Remarks
|
|
18-Jun-26
|
Perfluorooctane sulfonic acid (PFOS)
|
8 nanograms per litre
|
0.008
|
µg/L
|
<0.0001
|
Below ADWG limits
|
|
18-Jun-26
|
Perfluorooctanoic acid (PFOA)
|
200 nanograms per litre
|
0.200
|
µg/L
|
<0.0001
|
Below ADWG limits
|
|
18-Jun-26
|
Perfluorohexane sulfonic acid (PFHxS)
|
30 nanograms per litre
|
0.03
|
µg/L
|
<0.0001
|
Below ADWG limits
|
|
18-Jun-26
|
Perfluorobutane sulfonic acid (PFBS)
|
1000 nanograms per litre
|
1.000
|
µg/L
|
<0.0005
|
Below ADWG limits
|
Yass Water Supply - Old Quarry Bore Water 2025
| Date of Sample |
Parameter |
ADWG health-based values June 2025
|
Value |
Unit |
Old Quarry Bore Water T18
|
Remarks |
| 23-Jun-25 |
Perfluorooctane sulfonic acid (PFOS)
|
8 nanograms per litre |
0.008 |
µg/L |
0.0004 |
Below ADWG limits |
| 23-Jun-25 |
Perfluorooctanoic acid (PFOA) |
200 nanograms per litre |
0.200 |
µg/L |
<0.0001 |
Below ADWG limits |
| 23-Jun-25 |
Perfluorohexane sulfonic acid (PFHxS) |
30 nanograms per litre |
0.03 |
µg/L |
0.0002 |
Below ADWG limits |
| 23-Jun-25 |
Perfluorobutane sulfonic acid (PFBS) |
1000 nanograms per litre |
1.000 |
µg/L |
<0.0005 |
Below ADWG limits |
Water Supply - Yass Dam Raw water 2026
|
Date of Sample
|
Parameter
|
ADWG health-based values June 2025
|
Value
|
Unit
|
Yass Dam Raw Water R01
|
Remarks
|
|
18-Jun-26
|
Perfluorooctane sulfonic acid (PFOS)
|
8 nanograms per litre
|
0.008
|
µg/L
|
<0.001
|
ADWG Guideline limits do not apply to raw water. However, monitoring the raw water is to identify any contamination at the water source.
|
|
18-Jun-26
|
Perfluorooctanoic acid (PFOA)
|
200 nanograms per litre
|
0.200
|
µg/L
|
<0.001
|
|
18-Jun-26
|
Perfluorohexane sulfonic acid (PFHxS)
|
30 nanograms per litre
|
0.03
|
µg/L
|
0.001
|
|
18-Jun-26
|
Perfluorobutane sulfonic acid (PFBS)
|
1000 nanograms per litre
|
1.000
|
µg/L
|
<0.001
|
Yass Water Supply - Yass Dam Raw water 2025
| Date of Sample |
Parameter |
ADWG health-based values June 2025 |
Value |
Unit |
Yass Dam Raw Water R01 |
Remarks |
| 23-Jun-25 |
Perfluorooctane sulfonic acid (PFOS) |
8 nanograms per litre |
0.008 |
µg/L |
<0.001 |
ADWG Guideline limits do not apply to raw water. However, monitoring the raw water is to identify any contamination at the water source. |
| 23-Jun-25 |
Perfluorooctanoic acid (PFOA) |
200 nanograms per litre |
0.200 |
µg/L |
<0.001 |
| 23-Jun-25 |
Perfluorohexane sulfonic acid (PFHxS) |
30 nanograms per litre |
0.03 |
µg/L |
<0.001 |
| 23-Jun-25 |
Perfluorobutane sulfonic acid (PFBS) |
1000 nanograms per litre |
1.000 |
µg/L |
<0.001 |
Prior to the June 2025 update of ADWG Guideline limits
Yass WTP Treated Drinking Water
| Date of Sample |
Location |
Parameter |
ADWG Guideline Value, µg/L |
Value, µg/L |
Remarks |
| 23 July 2024 |
Yass WTP drinking water |
PFOS + PFHxs |
0.07 |
<0.0001 |
Not detected |
| PFOA |
0.56 |
<0.0001 |
Not detected |
Council will continue to work with NSW Health on monitoring for PFAS in the drinking water supply system and will report the results to the community.