Melbourne Water confirms zero detectable PFAS across Greater Melbourne catchments under new ADWG 2025 criteria
PFAS Monitoring Results in Greater Melbourne Catchments
Melbourne Water has published results from its 2024 to 2026 PFAS monitoring programme, confirming that source water across seven Greater Melbourne catchments contains no detectable concentrations of per- and polyfluoroalkyl substances. Independent testing conducted by NATA-accredited laboratories found that PFOS, PFOA, PFHxS, and PFBS were all below the programme’s limit of reporting of 2 ng/L. The results were published on 29 April 2026 and cover both protected and open catchments supplying the city’s potable water network.
The significance of this outcome is amplified by the regulatory environment in which it sits. The National Health and Medical Research Council released an updated version of the Australian Drinking Water Guidelines in June 2025, substantially tightening the health-based guideline values for key PFAS compounds. PFOS was reduced to 8 ng/L and PFOA to 200 ng/L under that revision. These figures represent a dramatic tightening of previous benchmarks and immediately elevated compliance scrutiny for water authorities, catchment managers, and environmental consultants working near or upstream of potable water supplies across the country. Against this backdrop, Melbourne Water’s clean dataset provides a regional baseline for PFAS site assessments, not simply a reassuring headline.
For environmental practitioners, hydrogeologists, site auditors, and their clients across Victoria and the broader contaminated land industry, this monitoring dataset carries practical weight beyond the water supply context. It establishes a well-documented, analytically sound regional baseline for surface water PFAS concentrations in the Greater Melbourne area. Under the PFAS National Environmental Management Plan 3.0 (PFAS NEMP 3.0), published in March 2025, the availability of reliable regional background data is a prerequisite for credible ecological and human health risk assessments. Melbourne Water’s results now provide exactly that reference point for practitioners conducting site assessments where surface water pathways are relevant.
Key details of Melbourne Water’s PFAS monitoring programme
The Melbourne Water monitoring programme was designed on a risk-based framework intended to identify early PFAS incursions into waterways that contribute to the city’s potable supply. The programme spans the 2024 to 2026 period and encompasses seven catchments, including both closed (protected) and open catchment systems. Sampling was undertaken by independent laboratories holding NATA accreditation, ensuring the analytical results meet the evidentiary standards required for regulatory and legal use. All four target compounds, being PFOS, PFOA, PFHxS, and PFBS, were reported below the 2 ng/L limit of reporting across every sample and every catchment included in this monitoring round.
The limit of reporting of 2 ng/L is particularly relevant when assessed against the June 2025 ADWG values. For PFOS, the new health-based guideline value of 8 ng/L means the analytical detection capability employed by Melbourne Water is running at one quarter of the regulatory threshold, providing a meaningful margin of confidence. For PFOA at 200 ng/L, the 2 ng/L reporting limit represents a detection sensitivity of 1 percent of the guideline value, which is analytically conservative by any standard. This level of sensitivity is precisely what is required to provide credible early warning monitoring, and the fact that all results remain non-detect at this threshold gives a high degree of confidence in the regional picture.
The programme covers both open and protected catchments, which is an important distinction. Open catchments permit some human activity and land use within the catchment boundary, introducing a higher theoretical exposure risk to PFAS from activities such as agriculture, firefighting training, or legacy infrastructure. The absence of detectable PFAS across open catchments as well as protected areas reinforces the effectiveness of Melbourne Water’s catchment management controls and the absence of diffuse contamination at the regional scale. This is not a trivial finding given the known persistence of PFAS in the environment and the range of historical land uses across peri-urban and rural Victorian landscapes.
The four compounds targeted by the programme reflect the priority PFAS substances identified under PFAS NEMP 3.0 and consistent with the ADWG June 2025 scope. PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid) are the most toxicologically studied long-chain PFAS compounds and carry the most stringent guideline values. PFHxS (perfluorohexane sulfonate) and PFBS (perfluorobutane sulfonate) represent shorter-chain compounds that have increasingly been detected as industry shifted formulations away from long-chain variants. Monitoring all four compounds simultaneously reflects current best practice under Australian and international frameworks and ensures the programme captures the breadth of current PFAS use patterns.
Australian context: PFAS NEMP 3.0, ADWG June 2025, and the Safe Drinking Water Act 2003 (Vic)
Australia’s regulatory framework for PFAS has undergone substantial revision across the past two years. PFAS NEMP 3.0, published in March 2025, replaced the 2020 second edition and introduced updated investigation criteria, revised ecological screening values, and clearer guidance on background concentration assessment, risk characterisation, and remediation target setting. A central requirement of PFAS NEMP 3.0 is that practitioners establish local or regional background concentrations before attributing site-specific detections to a point source. Without a defensible background dataset, risk assessors face the challenge of distinguishing genuine site contamination from ambient environmental concentrations.
References and related sources
- Primary source: www.melbournewater.com.au
- https://www.melbournewater.com.au/water-and-environment/water-quality/monitoring
- PFAS National Environmental Management Plan (NEMP)
- Australian Drinking Water Guidelines
How iEnvi can help
iEnvi provides specialist consulting services relevant to this topic. Our team includes CEnvP Site Contamination Specialists with experience across contaminated land, groundwater, remediation, ecology, and regulatory compliance.
- iEnvi groundwater services
- iEnvi remediation and validation services
- iEnvi expert services and independent review services
This is an iEnvi Machete news summary. Prepared by iEnvi to summarise the source article for contaminated land, groundwater, remediation, approvals and site risk professionals.
Published: 01 May 2026
Need advice on this topic? Speak to an iEnvi expert at info@ienvi.com.au or 1300 043 684, or contact us online.
Need advice on this issue? iEnvi provides practical, senior-led environmental consulting across contaminated land, remediation, ecology and environmental risk.
Contaminated land advice Remediation services Groundwater services Ecological assessment Talk to iEnvi