For starters, I can't even conceive of a body process that isn't dependent on water as a primary constituent, a catalyst, or an intermediary of other sorts.
The articles are out there--scientific journal ones even, not just opinions or compilations (which in this particular case are often still valid, even if not referenced).
In my clinical practice, I have seen HUGE benefits to getting people built up to consuming at least .5 ounces of water/1 pound of bodyweight. A rough guideline, and hardly individualized, but it seems to work for the most part. And these are relatively inactive folks in many cases. I've seen it work wonders from a pain management perspective, leading me to extrapolate that to mean that tissue healing times have decreased and inflammation has decreased--all things any human wants, including exercisers, of course. I've seen it play a role in relieving bowel issues, increasing energy, and allaying symtoms of depression and anxiety in some cases. While it's not a panacea, or "the" answer, the possibilities are limitless, and water is accessible and convenient for most people.
With those who rise above "average Joe" status, it is my experience personally and professionally that 3/4 to 1 gallon a day of water--consumed throughout the day--is optimal.
**This assumes the person in question does not have a condition making this unsafe or otherwise ill-advised. I am speaking of the normal, healthy, athletic population.**
Considering all of the anti-water we ingest regularly, such as medications, caffeinated beverages, processed foods, etc., and the dehydrating effects of sympathetic overload (stress) common in our society, those amounts are conservative, particularly if you are physically active.
But that's just my experience and opinion. . .
And I'm one of those weirdos with the water jug.
Helps me keep track of the single most important nutrient I take in each day.