The Metropolitan Water District of Southern California is bringing its fluoridation system up to par with other regions with its decision to add fluoride to Southern California’s water supply.

The MWD will start bringing fluoridation systems online at its five massive filtration plants over five weeks starting next month. The Robert B. Diemer Plant in Yorba Linda, which supplies about half of Orange County’s water, will start introducing fluoridated water into the system Nov. 19.

“With adding fluoride, Southern California is really playing catch-up with other cities throughout the nation,” said Bob Muir, spokesman for the district.

The district spent about $5.5 million on the chemical injection equipment to add fluoride to tap water and keep it at the 0.7 milligrams-per-liter level optimal for building of tooth enamel and preventing cavities.

According to the American Dental Association, fluoridated water costs about $1 per typical family every year. For every $1 spent, the ADA estimates fluoridated water prevents $38 in dental bills.

Edgar Dimally, the metropolitan district’s senior environmental specialist, said that tap water throughout Orange County already has varying levels of fluoride in it – depending on the time and place it’s tested.

“Metropolitan’s source water contains fluoride, but we’re adjusting it up to the optimal level,” he said. “Though there is some benefit from any level below that.”

Fountain Valley and Huntington Beach are the only cities that artificially add fluoride in Orange County now.