Millions of tourists visit each year to enjoy the fresh air, picturesque scenery and pristine bushland of the Blue Mountains, to Sydney’s west.
Unfortunately, the Blue Mountains are also the site of controversial research into water contamination with “forever chemicals,” also known as PFAS.
Our recent research investigated long-term PFAS contamination from two accidents involving gasoline tanker crashes and fires. Both incidents occurred in drinking water catchments, and our study found that contamination was present but undetected for 24 and 33 years, respectively. I searched overseas literature, but could not find any similar examples.
PFAS (per- and polyfluoroalkyl substances) are a broad category of thousands of synthetic chemicals used in numerous consumer and industrial products. Exposure to PFAS is associated with an increased risk of several diseases.
Our research shows how vulnerable drinking water supplies are to long-term PFAS contamination. It also shows how the lack of PFAS monitoring allows contamination to remain hidden.
two historic accidents
A 1992 petrol tanker accident at Medlow Baths in the Blue Mountains led to PFAS contamination of local drinking water supplies. And 32 years later, both reservoirs were forced to close.
Despite limited data, we identified the source of the contamination as a type of foam used by firefighters around the world to extinguish burning fuel fires. This foam material was mixed with water using perfluorooctane sulfonate, a type of PFAS.
Firefighters used the material to form a foam “blanket” to cover the burning material and extinguish the liquid fire. PFAS foams were used for decades before their harmful effects on human health and the environment were understood.
Nine years after the first petrol tanker accident, another fuel tanker accident and fire related to PFAS contamination occurred near Ourimbah on the NSW Central Coast in 2000. The fuel tanker was carrying 40,000 liters of fuel, but a collision with a passenger car caused an accident and fire. As a result, two people tragically died.
As with the Meadow Bus disaster, news footage shows water and foam being used to control the fire. Foamy outflow from the accident was also confirmed.
A sign for the closed Blue Mountains Water Treatment Plant in Katoomba, Blue Mountains, February 2025.
Mick Tsikas
Why are PFAS a problem?
PFAS, also known as “forever chemicals,” are a broad category of thousands of synthetic chemicals. They are used in numerous products such as non-stick cookware, stain-resistant fabrics, take-out food packaging, and even cosmetics.
PFAS molecules are not easily broken down and easily accumulate in the tissues of wild animals around the world. Exposure to small amounts of PFAS causes the chemicals to accumulate in vital organs in animals and people. Analysis of human autopsy revealed that PFAS accumulates in the brain, lungs, liver, kidneys, and bones.
In 2025, an Australian Bureau of Statistics report revealed that almost all Australians have a buildup of PFAS chemicals in their bodies.
Should I worry?
Exposure to PFAS is associated with an increased risk of several diseases. These include decreased fertility, increased blood pressure, increased risk of cancer (particularly prostate, kidney, and testicular cancer), liver disease, increased cholesterol, and obesity.
A person can ingest PFAS through ingesting food or drinking water that contains PFAS.
The Upper Blue Mountains water supply serves approximately 40,000 people and is operated by Sydney Water Corporation. The report said PFOS, one of the most dangerous forms of PFAS, reached 16.4 nanograms per liter in local drinking water on June 25, 2024. This is double the safe amount according to the recently revised Australian Drinking Water Guidelines.
The discovery of PFAS led to the closure of two drinking water reservoirs downstream of the Meadow Bath petrol tanker accident and fire. Although the lack of testing data creates uncertainty, PFAS contamination may have gone undetected in the Blue Mountains’ drinking water supply for more than 30 years.
Associate Professor Ian Wright collects water samples from streams in the Blue Mountains.
Fleur Conic, Provided by the author (not reusable)
What our research showed
Our research showed that as of October 2025, contaminated creek water contained between 2,000 and 2,400 ng/L of PFOS. This is 250 to 300 times the maximum safe concentration (less than 8 ng/L) recommended by the Australian Drinking Water Guidelines.
The Blue Mountains pollution plume spread downstream to Greaves Creek in the upper Blue Mountains. The stream is part of the UNESCO Blue Mountains World Heritage Area and has PFOS levels that exceed aquatic ecosystem guidelines by a factor of 100. The safe level of PFOS concentration for the protection of freshwater species is 0.23ng/L.
To our knowledge, the PFAS contamination identified in this study has not undergone remediation actions to remove contaminated soil or water. Most PFAS contamination across Australia occurs at sites where PFAS foam has been used in repeated firefighting training operations. Our research shows that even a single incident involving PFAS can have long-term environmental impacts.
