Residents of the bushfire-ravaged Bega Valley have become the latest to rely on carted water.

Flooding has made water supplies undrinkable in the Bega valley, leaving residents relying on water carted in milk tanks.

Bega Valley shire council has been trucking bore water from Bega for towns including Bermagui, Cobargo and Quaama. The Australian Defence Force has set up a mobile water treatment plant to filter the water supply at the Brogo dam.

However, the Brogo catchment was hit by disastrous fires in the first week of January, leaving no trees, grasses or other vegetation to stop sediment, ash and other organic debris washing into the Brogo dam.

Residents are now under level four water restrictions, with the dam overflowing by about 200 megalitres a day.

The council has called for financial assistance from the New South Wales government to build a temporary water treatment plant at a cost of about $300,000.

The NSW government has pledged up to $350,000 for emergency water carting until 10 March, or until normal supply is restored.

A permanent treatment plant was promised by the state government in 2018 but has not progressed since then.