The federal government will pay out $212.5 million to settle three class actions launched by victims of toxic firefighting contamination across Australia.

$86 million will be paid to about 150 residents in the Williamtown red zone after a four year legal battle.

Class actions were also launched by residents in Oakey, Queensland and Katherine in the Northern Territory.

The settlement is believed to be the first of its kind in the world.

PFAS was used in firefighting foam on defence bases, with the chemicals leaching into surrounding soil and water.

There are at least 90 contaminated sites nationally.

Class action lawyers are currently investigating the possibility of legal action at a further 24 military bases across the country.