Lead defence spokesman Steve Grzeskowiak revealed further testing since last year’s report was made public had produced more evidence of PFAS contamination in the Tindal RAAF Base area.

PFAS is a family of chemicals which were contained  in firefighting foams used in training at the base which have since leached into the groundwater.

Power and Water has found elevated levels of PFAS in the town’s sources of drinking water, notably the two bores used at the water treatment plant.

Steve Grzeskowiak, defence’s deputy secretary Estate and Infrastructure, did not provide any further information about the new positive contamination results.

He said a 12-month long study into the Tindal contamination had already started.

He said bores would be dug, fish and plants tested, along with water supplies.

He said a water use survey would be launched in the Katherine area in the next “month or so”.

“We want to get a comprehensive picture of where the chemicals have moved in the landscape,” he said.

He said the study would now include a human health assessment although there was no indication of whether this would include voluntary blood testing.

He said although the study would take about a year, defence would return to Katherine several times to update community on the results.

“We want to keep people informed about what we are doing,”  Mr Grzeskowiak said.

He said defence would be discussing with neighbours of Tindal, more than 40 properties are already being supplied with alternate water supplies, about providing rainwater tanks at the government’s expense.

There was no discussion about the provision of safe water to any other areas outside the immediate area of Tindal.

Federal deputy chief medical officer Tony Hobbs said authorities had lifted safe PFAS limits from 0.5 to 0.07.

He said there was still “no consistent evidence” of the chemicals doing people harm but health authorities needed to take a precautionary approach.

Dr Hobbs said the occasional increase over the recommended limit “would not do any harm”.

He said blood tests would provide little useful information other then to tell the person tested whether they had been exposed to PFAS.

A second meeting at the Katherine Country Club will begin at 5.30pm.