There is a lot more behind water toxicity than I personally know, just as a disclaimer.

What I was trying to say is that if there is too much water in your blood, your kidneys are being forced to expell only water. This may or may not be an issue for higher levels of minerals that may accumulate as a result, even though they would be heavily diluted. There are going to be other imbalances caused, I suppose.

From what I understand as well, keeping hydrated is good. However, there are a million different body types and a million different environmental factors that come into play. The general rule of thumb is drink water when you are thirsty, not heavily caffeinated beverages. Unless you are an athlete, Gatorade-like spots drinks aren't the best choice either.

When I was working in extreme conditions at one point in my life, I could easily drink several hundred fl.oz of water during a shift and rarely pee. It was so hot, I would just sweat it all out. This did require that I regularly drink sports drinks to help maintain balanced sodium levels. I was constantly thirsty because my body needed water, and lots of it. (I was working in +100F temps, in full protective gear, while being very active.)

My point is that running a mile or two is not "extreme" or just going about your daily life is not "extreme". There is no need to flood your body with water if you don't need it. If we drink water instead of other crap beverages, we can just let our bodies do their thing naturally: Drink water when you are thirsty.