> Would that be calcium flouride or sodium flouride?  

Hi Oliva:

I don't know actually - I usually only see it written down as fluoride.

But levels are apparently quite low in water at 1 ppm and are well within safe levels.

http://www.answers.com/topic/fluoride

Fluoride: 
 A binary compound of fluorine with another element.

Fluoride is an important trace element in human nutrition. Daily exposure to small quantities is widely considered to be vital for maintenance of sound tooth structure. Ingested or systemic fluoride has long been known to offer significant benefit when supplied during tooth formation in childhood. More recently, topical exposure (that is, making fluoride available at the tooth surface) has been shown to provide benefits throughout life, even for older adults.

[...]

The U.S. Environmental Protection Agency has set a standard of 4.0 ppm as the maximum allowable fluoride level in drinking water. Within the United States, fluoride levels in drinking water are actually maintained at about one-fourth of this level. However, in some developing countries, particularly in southern Asia and northern Africa, natural fluoride is present at extremely high levels. In India, for example, a study sponsored by the World Health Organization found natural fluoride levels exceeding 1.5 ppm in about 8 percent of samples, with some concentrations as high as 22.0 ppm. In such areas, public health workers actively engage in efforts to reduce fluoride exposure and eliminate fluorosis."

By the way, here is an interesting website (its called the Pollution Information Site) with a very large database of chemicals with about 30 lisitngs of differing types of fluoride:

http://www.scorecard.org/smart-search/one-word.tcl?query_string=fluoride&x=8&y=4

Fluorine:

According to this site fluorine is "Ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health." Fluorine is an element and is very, very reactive and dangerous.

Marilyn