LEGISLATION forcing local authorities to fluoridate their drinking water has been introduced to the NSW parliament amid condemnation of the "anti-fluoridation circus".

Opposition health spokesman Andrew McDonald introduced the laws on Thursday.

Local councils can currently choose not to add the dental health booster to their water supplies.

The legislation, which comes after a fluoride backlash by some communities, means the state government will be able to force local authorities to fluoridate public water supplies.

About 300,000 people in NSW currently don't have access to fluoridated water, which Mr McDonald described as "one of the most cost-effective health interventions ever used".

"Every day without fluoride puts a child at risk of preventable dental decay," he told the lower house.

"It's time for the NSW government to step in and take control."

It follows several recent attempts from local councils to block fluoridation.

On Wednesday night, Lismore Council overturned a ban on fluoride after seven years of lobbying by local health professionals.

Mr McDonald said the government could not afford to risk local councils being intimidated into opposing fluoridation by "a fringe element" of the community.

"For many of these children the damage has already been done," he said.

"It's time for this anti-fluoridation circus to end."

Originally published as NSW bill targets 'anti-fluoride circus'