Q: Does it (the Stefani Water Purifiers) filter out flouride?
A: Yes, and no! There are NO gravity or domestic, water purifiers that filter out ALL fluoride. The ones that claim to most often use aluminium to precipitate it out, leaving you with an Aluminum AND fluoride residue. The triple-action Stefani filters can absorb 10-50% of the fluoride in the water from the beginning of use to 6 months. It depends, too, on how much fluoride is in and added to your water. How much is added to your water?
In Toronto, it's 0.6mg/L, and 0.5mg/L is the detectable level, so tests would show that the Stefani removes all the fluoride.
You may want to refer to the Water Fluoridation in Toronto Staff Report to contextualize concerns about fluoride in drinking water.
Following changes at the national level, the Ontario Ministry of the Environment (MOE) lowered the fluoride level standard in 2000, from 1.0–1.2 mg/L to 0.5–0.8 mg/L (4). The level of fluoride in Torontowater was reduced from 1.2 mg/L to 0.8 mg/L in 1999 and then to 0.6 mg/L in 2005. Therefore the City of Toronto is in compliance with the Federal and Provincial standards for safe drinking water, as presently defined. At 0.6 mg/L, the drinking water of Toronto actually has a lower level of fluoride than that which naturally occurs in some parts of Ontario, e.g.Stratford(1.4 to 2.1 mg/L), St. Pauls (1.59 mg/L), Mitchell (1.93 mg/L), Sebringville (2.76 mg/L), and St. Mary's (1 mg/L).