I genuinely don’t know how to respond to this person

“Yes”

“Well, yeah mothafucka, there is.”

This is the only reasonable way to reply to someone asking such a stupid question to try to make some point. If this is a product’s official response, whatever it is, it’s safe to assume your suspicions were correct.

Seeing how dumb you are with that comeback, I can see why they’d question you. Yes, there are many, many studies showing that water is good for you.

I don't know the context, but the best answer is to post a link to said research.