The fire station at Avalon Airport has been closed after unsafe levels of PFAS were found in the drinking water.
The union representing aviation firefighters said the firefighting chemical was also detected in the water supply at the air traffic tower south-west of Melbourne.
Airservices Australia, which operates firefighting and air traffic services at the airport, confirmed it had closed the fire station while a new water supply was set up and a deep clean was undertaken.
"Our highest priority is protecting the health and wellbeing of our teams," a spokesperson said.
"Airservices' 30 aviation rescue firefighters and two air traffic controllers stationed at Avalon have been offered expert health advice and free blood testing."
Avalon Airport said drinking water inside the terminal had not been affected and flights were operating as usual.
The Civil Aviation Safety Authority has been notified of the fire station closure and told Fire Rescue Victoria crews will step in until the situation is resolved.
The Environment Protection Authority, Barwon Water and relevant Commonwealth departments have also been notified of the detection.
United Firefighters Union aviation branch secretary Wes Garrett said his members were very concerned about the news.
"Those levels were in excess of the drinking human health recommended threshold values," Mr Garrett said.
A spokesperson for Airservices Australia said the threshold for safe levels for drinking water was 70 parts per trillion, and that levels detected in the tower and station were at 5,800 parts per trillion and 3,080 parts per trillion respectively.
Mr Garrett said the union was unaware how long the chemical had been in the water.
The source of the contamination is still unknown, with Airservices Australia saying it has never used firefighting foam containing PFAS at Avalon.
But Avalon Airport said it had been used in the past.
"As with many Commonwealth-leased airports, PFAS was historically used as part of aviation and defence activities which is a multi-decadal legacy of practice at Commonwealth Airports," a spokesperson said.
"Since receiving this information, Avalon Airport has launched a full investigation into this matter.
"This is a new and emerging situation and we are responding as quickly as possible to investigate these findings and understand the facts to best manage an evolving situation."
The United Firefighters Union said it was concerned about the ability of Fire Rescue Victoria (FRV) to respond to an incident at the airport as crews did not have specialist aviation emergency training.
Firefighting chemical has long legacy in Victoria
PFAS chemicals are per- and polyfluoroalkyl substances that are manufactured for use in products that resist heat, oil, stains and water.
Countries such as New Zealand have banned PFAS chemicals because they can accumulate in the body and have been linked to a number of health concerns.
The Victorian government recently announced a $57 million redress scheme for firefighters who were exposed to PFAS at the former Fiskville training facility.
Work on the West Gate Tunnel project stopped in 2019 after PFAS was found in the soil, leading to massive cost blowouts and a dispute over who would pick up the bill for the disposal of the soil.
