SAN FRANCISCO — The San Francisco Public Utilities Commission approved a plan Friday that would expand the distribution of fluoridated water to nearly a half million Bay Area customers, despite a significant amount of outcry and admitted misgivings by some members of the commission.

The decision had to be postponed from Tuesday’s meeting due to a lengthy public comment session, which resulted in lack of a quorum because several members had to leave to take care of prior commitments.

The commission approved the East Bay plan because it would cost $5.8 million less to build a new water-treatment site in the East Bay than to update the current water-treatment site in San Mateo County.

The plan would also bring fluoridated water to 436,000 SFPUC customers who are currently not receiving fluoride in their water.

Commissioner Dennis Normandy voted for the East Bay Plan, but noted his own concerns after hearing outrage from residents at both meetings.

“I approached this topic with a good deal of fear and apprehension,” Normandy said, acknowledging recent governmental decisions that have hurt the public, such as airline and power deregulation. “My tendency was to take into account that every scientific study has little credence to those that are negatively effected by an issue.”

Cities such as East Palo Alto, Redwood City, Half Moon Bay and Woodside will all receive fluoridated water under the new plan. Most North County cities already have fluoridated water.

Dozens of residents filled both meetings to denounce the plan and try to keep fluoride out of their water, but they were countered by others, including the top health officials from San Francisco, San Mateo, Alameda and Santa Clara counties, who supported the expanded fluoridation.

The East Bay Plan was supported by the University of California San Francisco School of Dentistry, the California Dental Association, the California State Department of Health Services and the Center for Disease Control.

Those who oppose the plan say that fluoride is a hazardous chemical that causes maladies such as bone deterioration, lowered IQ and hardening of blood vessels.

“Fluoridation is a fraud and we don’t want it on the Peninsula,” Billie Barewald of Mountain View told the commission Friday.

Others expressed concern that they had no choice in the matter, and would be receiving the fluoride without any type of vote from local communities or cities. Some residents who don’t want fluoride in their water say that it would be cost prohibitive to remove the fluoride from the water or buy bottled water.

Those in support of fluoridation say they were pleased with the commission’s decision.

“We see too many kids with dental decay,” said Sally Brother, the health services manager for San Mateo County. “What we really need is an effective form of intervention and that would be the East Bay alternative.”

“We are going to save millions of dollars so every small community doesn’t have to pay to fluoridate their water supply,” said Howard Pollick, a clinical professor at UCSF and Diplomate from the American Board of Dental Public Health.

Pollick said he thought that the concentration of fluoride in the water would be modified due to the different micro-climates in the Bay Area in order to protect people from fluorosis, a condition that damages teeth due to too much of fluoride.

The plan must undergo an environmental impact report and certification by the San Francisco Planning Commission before final adoption by the SFPUC.