An initial investigation by WaterNSW has disclosed that residents in the Blue Mountains may have consumed drinking water contaminated with per- and polyfluoroalkyl substances (PFAS), known as 'forever chemicals', for as long as 32 years.

The contamination led to the disconnection of Medlow Dam and Greaves Creek Dam from the drinking water supply of approximately 78,000 individuals in August 2022.

PFAS chemicals identified in the water supply have been associated with a toxic firefighting foam that was banned in Australia in 2007, suggesting that the water was likely tainted for a substantial period prior to that ban.

WaterNSW's findings indicate that the contamination might date back as far as 1992, coinciding with a petrol tanker accident on the Great Western Highway near Medlow Bath, which involved the use of over 400 litres of PFAS-rich firefighting foam by emergency crews.

Further investigation into potential sources revealed that a 2002 vehicle crash and the Medlow Bath Rural Fire Brigade Station could also have contributed to the contamination.

WaterNSW's examination of 250 samples collected from 37 locations indicated notably high PFAS levels in the Adams Creek tributary, specifically near the Great Western Highway and within the township of Medlow Bath.

The decision to disconnect the dams was based on government testing that detected PFAS levels of 0.09 micrograms per litre, which exceeds the Australian drinking water guideline of 0.07 micrograms.

However, independent testing commissioned shortly thereafter revealed PFAS concentrations in Adams Creek at 3.7 micrograms per litre, significantly exceeding safety thresholds.

In September 2022, the New South Wales (NSW) government mandated statewide testing of all local drinking water supplies for PFAS, following rising community concerns.

The National Health and Medical Research Council subsequently proposed new guidelines aimed at substantially reducing the allowable levels of PFAS in drinking water.

Local community activist Jon Dee, who heads the STOP PFAS action group, expressed dissatisfaction with WaterNSW's investigation, citing unresolved questions regarding the onset and extent of PFAS contamination in the area.

He highlighted that the investigation had not provided clarity on the duration of toxic water consumption by residents.

Surface-level assessments identified PFAS levels near Medlow Dam, Greaves Creek Dam, and Adams Creek as being considerably above current safety standards, with the Cascade Dams, which continue to supply drinking water to residents, also reporting levels exceeding proposed guidelines for PFOS—the most notorious PFAS compound.

Although WaterNSW conducted sediment testing at Medlow Dam, accessibility issues prevented similar tests at Greaves Creek Dam, and concerns over potential chemical release led to caution around sediment collection from the Cascade dams.

In December 2022, Sydney Water installed a $3.4 million interim treatment system at the Cascades Water Treatment Plant to align water treatment efforts with the new proposed guidelines.

Sydney Water affirmed that the drinking water supplied to the Blue Mountains is currently safe.

Despite official reassurances, residents continue to report health issues potentially linked to PFAS exposure.

Case reports have emerged detailing elevated PFAS levels among local individuals, including instances of various cancers within families.

Following these reports, local activists have called for government-supported health testing for affected residents and are preparing a class action.

NSW Health Minister Ryan Park has stated that current health guidelines do not recommend blood testing, deeming low-level exposure unlikely to result in significant health problems.

However, he mentioned that an expert panel has been convened to evaluate ongoing health concerns as new evidence continues to emerge.