Let's start by setting aside a couple of myths about the fluoride being added to your drinking water.
1. It is not part of a vast government conspiracy to control the human population.
2. It will not prevent cavities from forming by itself (sorry kids, you still have to brush your teeth)
So what does it do and why did they start adding fluoride to our drinking water? The simple answer is that a government health review of fluoridated water shows that it helps reduce tooth decay by as much as 60%. Dentists used fluoride treatments to help fight cavities, but that only worked for the people who could afford regular dentist visits.
By adding fluoride to all drinking water the goal was to give everyone access to the benefit of fluoride treatments. In low doses it is not harmful to humans. About 10% of people may experience Dental Fluorosis due to the presence of Fluoride in their drinking water. Dental Fluorosis only occurs during tooth formation and ranges from mild (symmetrical whitish areas on the tooth) to severe (brownish discoloration) and is considered a cosmetic problem not a health risk.
Personally I would not want a very high amount of fluoride added to the public water supply, particularly in areas that already have naturally occurring fluoride in the water. But I can also see the benefits of having a small amount added to the water to help preserve healthy teeth.
I get asked a lot whether or not a carbon based water filter will reduce the level of fluoride in water and the answer is no, they do not. If you want to remove fluoride you would need to use a reverse osmosis system, but these are very expensive and in addition to removing fluoride and other harmful contaminants take out all the naturally occurring minerals that your body needs. My advice would be if you are worried about fluoride levels in your water have it tested to make sure it is not too high.