I have a very good friend who's a dentist. He understands and agrees with the general flourode in the water and general chemical treatment of water concerns, however, he stresses that fluoride protects your teeth and you should use toothpaste with it. Definitely don't want to be drinking it, but you spit it out and rinse with water.

Also, side note, charcoal is terrible for your teeth. It wears down the protective enamal. May look whiter immediately but your setting up a long-term problem.