I should probably post this in /r/askscience but I don't like posting on defaults, and y'all know saliva, so...here goes.

In my neck of the woods, farmers and ranchers use cold water cut with a little bit of tea to quench thirst. That is what I drink most of the day as well, as it does seem to work better than just drinking water. Am I imagining that it works better? Or is there any science behind this?

Do tannins increase saliva flow? Is that why it works? Could it be something else? Could it be that we just appreciate a little bit of flavor in our water, and drink more of it?

Related question - am I damaging my teeth by drinking water cut with tea all day long? I understand there is a risk of staining, but is there any other harm? It's not sweetened, of course.