Patrice
I also had Reverse Osmosis filter for many years as it seemed to be the only unit available that screens out the majority of fluoride although not totally.Unfortunately it also leeches out most of the minerals natural to the water and leaves the body mineral deficient.
My understanding of fluoride is that the form used in drinking water is 'sodium fluoride' which doesn't occur naturally in nature but is a by-product of superphosate fertilizer.It was derived from Aluminum smeltering in the past.
It calcifies the pineal gland and bones,mottles the teeth and is used as the main ingredient 1080 poison baits.