Crescenta Valley Water District imports about 40% of its water from the regional supplier, said Vasken Yardemian, board member for the water district.
About 70% of Glendale's water is purchased from Metropolitan, said Dan Askenaizer, senior environmental program specialist for Glendale Water & Power.
"There's tremendous benefits from doing something like this," he said.
Most dentists and public health officials have for years touted fluoridated water as an important tool in combating tooth decay, despite a decades-old debate waged by environmental groups who argue the chemical is unnecessary and potentially unhealthy.
HOW IT WORKS
Minerals are stripped from teeth at a slow and steady pace as acids from the mouth constantly attack enamel.
Fluoride helps to re-mineralize the enamel as it binds with calcium and other compounds in the saliva, making the tooth more resistant to tooth decay, health officials say.
Saliva has a continuous supply of the fluoride if it is ingested and enters through the bloodstream.
"I think it's very helpful," said Gary Finer, a local dentist and president of Glendale Healthy Kids, a nonprofit group that provides health care to low-income families. "It should have been done years ago."
Cities across the nation have been fluoridating their water for decades.
Los Angeles has added the substance to its supply since 1999 and Long Beach has since the 1970s, said Edgar Dymally, senior environmental specialist for the Metropolitan Water District.