Drudge is linking to the NYT article "Study Cautions Runners to Limit Their Water Intake" (link) about hyponatremia, also known as water intoxication. My suggestion is that while the article has some worthwhile information, if you hike in the southwest U.S. you might want to consider the source. No, not because it's Drudge, or even because it's the NYT, but because of the fact that the NYT is from the northeast and their suggestions might not apply to the southwest or might not apply to hikers.

I don't think I've ever had the problem of having had too much water to drink. On the other hand, I can think of at least a couple cases where I didn't have enough water and I felt really bad afterwards. If you're hiking in hot and dry weather drinking copious amounts of water is a necessity. The idea is that your urine should be clear and copious. See this, this, this, and this.

What I do is take about a liter of water per hour plus Gatorade or similar. For longer hikes I eat something sweet and something salty occasionally. Then again, I don't just perspire, I exude. And, I probably have a good deal more mass and surface area than the marathoners mentioned in the article.

Note also that both the desert and snowy mountains are generally dry areas. While snowy mountains are almost always colder than the desert at the same time of the day and year, I've also been less than clear and copious in that environment. So, I'll continue to drink enough to maintain my clarity and in large enough volumes, I just won't overdo it.

[DISCLAIMER: I am not a medical professional and this post does not constitute medical advice, simply person opinion. Consult your medical professional.]