Katoomba Water Safe as PFAS Investigation Begins

NSW investigators target three historic sites to trace PFAS sources and secure the Blue Mountains drinking water supply for 41,000 residents

16 Mar 2026

New South Wales officials have commenced a detailed forensic investigation into the origins of forever chemicals within the Blue Mountains drinking water catchment, marking a significant escalation in the state’s response to long-term environmental contamination. The probe, announced on March 10, 2026, focuses on the upper catchment area that feeds the Cascade Water Filtration Plant, which provides drinking water to more than 41,000 residents in and around Katoomba.

The investigation follows preliminary findings by WaterNSW that pointed to three primary sources of per- and polyfluoroalkyl substances, known as PFAS. These include the sites of two highway tanker accidents in 1992 and 2002, where aqueous firefighting foams were deployed, and the Medlow Bath Rural Fire Brigade station. Analysts noted that chemical signatures found in local soil and water samples were consistent with the specific foam compositions historically used by emergency services at those locations.

Concerns regarding the catchment first emerged in June 2024, when initial detections prompted authorities to disconnect two dams from the regional supply network as a precautionary measure. To maintain water safety, a 3.4 million AUD mobile treatment facility utilizing granular activated carbon and ion exchange technology has been in operation at the Cascade plant since January 2025. Officials said the treated water currently meets Australia’s stringent new drinking water guidelines, which were revised in June 2025 to reduce the allowable limit for PFOS from 70 nanograms per liter to 8 nanograms per liter.

The current phase of the inquiry, overseen by the multi-agency Blue Mountains Project Control Group, involves rigorous testing of groundwater, surface water, and sediment around the identified suspect sites. While the treatment technology provides a secondary layer of defense, the environmental data gathered during this period is expected to dictate the scope of long-term remediation efforts.

The Blue Mountains case is increasingly viewed by experts as a critical test of how jurisdictions manage legacy contamination from diffuse, decades-old sources. As the investigation proceeds, the findings are likely to inform national standards for catchment management and the mitigation of persistent chemical pollutants in public infrastructure.