BEAVERTON — By a 53-to-47 ratio, Beaverton voters were favoring a recommendation the city add fluoride to the water it supplies to about two-thirds of city residents.

The fluoridation question, forwarded to voters by the City Council in August, was intended as an advisory vote about whether to take the step.

Mayor Rob Drake said planning and budgeting to add fluoridation would proceed with a positive vote.

Beaverton, which supplies water to about 50,000 of its 78,000 residents, would join the adjacent Tualatin Valley Water District, which since 1963 has added fluoride to its supplies north and west of the city.

The district serves about 15,000 city residents. Two other districts without fluoridation supply others.

Stand for Children, a health-care advocacy group, urged Beaverton to fluoridate its water, arguing that adding the chemical would over time reduce if not eliminate dental cavities in children and adults.

Oregon Citizens for Safe Drinking Water, an anti-fluoride group, argued that some scientists have questioned the safety and necessity of fluoridation. The group also said fluoride chemical production as a fertilizer byproduct did not have proper purity safeguards.