A NSW community is taking legal action after cancer-causing chemicals were found in their water supply.

A group of 450 people living within five kilometres of the Williamtown air force base (an area known as the “Red Zone”) have launched a class action.

The group is seeking compensation, claiming their homes are now worthless due to the contamination.

The RAAF used a toxic fire-fighting foam for over 40 years, which leaked into and contaminated the area’s water supply.

The fire-fighting foam contained PFAS chemicals, which have been linked to cancer.

Residents have been told to not use their own bore water or to eat their home-grown vegetables, eggs, dairy and livestock.

The RAAF has been providing bottled water for some homes.

Locals claim there has been a spike in cancer cases in the area, but that the only medical assistance being offered are blood tests which measure PFAS levels.

These tests have only added to the concern of some families, with even infant children returning high levels of the chemicals.

Many families have decided to move, only to find out they are unable to sell their homes as property values have plummeted, prompting the class-action suit.

Residents around a military base in Oakey, Queensland, have launched a similar class action, and similar contamination has been revealed near an RAAF base at Katherine in the Northern Territory.