what is fluoride and why is there a debate around it fluoride is a mineral that occurs naturally in soil and water decades ago researchers found it was effective in preventing cavities the addition of fluoride to drinking water was considered one of the great Public Health achievements of the last century fluoridated Water Systems serve about 2third of the US public but some Studies have raised questions about whether fluoride affects brain development in kids a federal judge recently ordered the EPA to further regulate fluoride and drinking water in the meantime some communities aren’t waiting and have already decided to stop adding it to the drinking water