You can't though in practice. If you live in urban area for example. It's functionally equivalent. If you say well, I could say gas mask with tank. If you say bottled water, I could say respirator, etc.
The thing about safety nets is they actually have to be, you know, safety nets. If you can just avoid them then they don't provide any safety. Look at SS. If we just get rid of SS, then we're fucked. It's true other investments exist and are better. But that's not the whole story. People won't invest, so we have to force them. Otherwise, they suffer, and we suffer, too, because ultimately we don't want dead geriatric bodies piling up on the streets.
The idea of fluoridated water is it's a safety net. So even the poorest, most mentally-ill among us have a baseline guarantee of dental health. And, for that purpose, it's extremely effective.