I've heard that the soft drink 7-up once contained lithium among its ingredients. I don't think it's a good idea to add lithium to drinking water because of it

I've heard that the soft drink 7-up once contained lithium among its ingredients. I don't think it's a good idea to add lithium to drinking water because of its toxicity, but I don't see anything intrinsically wrong with adding chemicals psychoactive or not to the drinking water for the purposes of public health. If it is permissible to add fluoride to water to improve the average smile, I don't see how one could object to adding a chemical to improve the average mood. (provided that the chemical was otherwise harmless)