Replied by Ted (Bangkok, Thailand)
Dear Sabrina: The research study that I remembered conducted using borax for fluoride removal or at least chelate the fluoride out or reduce the fluoride toxicity.
To remove chorine is very simple for the bathtub. Go to a aquarium shops, they will have a bottle of dechlorinator. The dechlorinator that I used is sodium thiosulfate 10% in water.
Most dechlorinator should at least mention the active ingredients. This will prevent the manufacturers from putting harmful substances in their product. Of course the manufacturers do not like this as it lowers their profit margin if the buyer knows the exact ingredients possibly giving the consumer a chance to make their own solution.
On the other hand you can get a better prices from a swimming pool supplier. It is usually ideal for you to get most of the supplies you need and they might also have sodium thiosulfate to remove chlorine from the water at a much better price.
Should you be able to contact the swimming pool suppliers ask them for chlorine and fluorine removal, as well as other supplies that can remove other unwanted polluted city waters from your shower and water filter.