Trisha, the reason we add chlorine et al to water is to make the water itself safe to drink.

The reason we add fluoride compounds to water is to effect a change in the health of the people who drink it  --  which is the very definition of "medication."

Say what you like about the benefits and/or hazards of fluoride additives, we are using them because we believe it will change the health of the people who ingest them.  Only fluoride is added for this reason.