Residents from the Northern Territory town of Katherine are "shocked and disgusted" and want the Defence Department and Federal Government to "cut the crap" and take action over chemical contamination of the town's water supply.

Katherine was exposed to toxic chemicals from firefighting foam used at the nearby Tindal RAAF base in the late 1990s and early 2000s, and is one of several sites around the country affected by the chemical group known as PFAS.

A Four Corners investigation has revealed Defence was explicitly warned about the chemicals' impact on the environment as early as 1987, two years before the RAAF base at Tindal opened operationally.

"Show some leadership, cut the crap out about talking and spinning it … we have a problem, come and fix us and come and tell us how to fix it," said resident Bill Daw, who called on Defence Minister Marise Payne and Northern Territory senator Nigel Scullion to visit Katherine.

"The fact that Defence has known for so long about the potential damage that PFAS could do … I'm just flabbergasted as to why nothing's been done."

Resident Amanda Kingdon said the Government had failed to protect the community.

"I'm shocked and disgusted," Ms Kingdon said.

"They need to take serious quick action to help the people that are most concerned and just do blood tests, do everything they can to help people who are in a vulnerable position and left hanging."

Another resident, Danielle Campbell, said Defence had not been honest.

"They definitely didn't want to share their information and let people make their own choices," she said.

"We could've had cleaner water sooner."

The member for Katherine, Sandra Nelson, said Defence had been "reckless and careless" and should have told the public about PFAS contamination a long time ago.

"They were made aware of the issues of exposing PFAS to the environment … decades ago, and I'm just incredibly disappointed and shocked that that wasn't actually revealed to the general public," Ms Nelson said.

Children played in firefighting foam

The source of the chemical pollution was the widespread use of firefighting foam. ( CRC CARE )

Greg, a firefighter in Katherine for 15 years, said children used to play in the contaminated foam at the local fire station after it had expired and was no longer being used at the RAAF base.

"We'd bring it back into Katherine at the fire station and practice with it, and we also did a street parade every year, get the foam out and let the kids all run through it," Greg said.

"We did that for four, five years in a row, and then it'd all just wash down the main street, into the gutters and into the Katherine River."

The Defence Department said it wanted to be open and transparent in cleaning up the problem.

"We certainly don't walk away from the fact that, yes, we used these products, we put them into the ground in firefighting foam at the time," said the department's deputy secretary, Steve Grzeskowiak.

"At the time that was done, in the 70s, 80s, 90s, in various places they were believed to be safe, and certainly that's what the manufacturer was saying.

"Clearly when you look back the practices that were in place, they were not good, they certainly wouldn't meet any standards that we'd have in place today."

As a precautionary approach, Defence said it was supplying about 50 properties in the Katherine area with bottled water.

Defence said it has taken about 1,000 samples of soil and surface and groundwater in the Katherine and Tindal area, and would publish a report on the findings early next year.