Personally I think water IS important. I was tempted to change how much water I drink each day when I have read recent researches that say "Over-doze of water is bad for your kidneys..", "1 liter of water a day is plenty..", etc.
1. Human body
The amount of water in the human body ranges from 50-75%. So ignoring loss of water (perspiration and other bodily waste) is ignoring essence of yourself. You don't need to be spiritual person to acknowledge this fact.
2. People vs mammals
We discussed this with my gf. We compared ourselves to animals. Most mammals will drink enormous amount of water even if they have water in territory. People don't do that. We very rarely consume large amounts of pure water. Actually we "forgot" to drink cause it's available any time. I think we suppressed even the subconsciousness survival instinct of thirst.
3. Water vs other liquids
Oh I drink coke. I drink beer. People say often. Sorry, get the facts about nutrition. If you have too much sugar in your blood, kidney will start to produce more urine to eliminate it. Similarly with alcohol. Coffee and tea dehydrates you as well. Then there are mineral waters. They can be a very good supplement of minerals, but if you drink mineral water too often your kidneys will not like it.
4. Hydration and sports
Anyone who does sports knows importance of this. I heard some sportsmen drink enormous amounts even outside the main season.
Interesting finds about hydratation:- Many people are most de-hydrated in the morning. A glass of clean, non-sparkling water helps to recover the losses and can kick-start the metabolism. Tested, works.
- If you drink large amounts of tea or coffee, like I do (5 cups pf green tea daily), you should balance the amount with water.
- Timer set for 15-30 minutes is a good reminder for few gulps of water
I don't always follow above, but I try my best. In average I drink 0.35 galon (1.3 l) of water, plus some green tea, plus soup, a glass of veggie or fruit fresh and a beer a day. On days I do sports (swimming, basketball, cycling) I add another 1.3 l on top.
Please don't say this too ascetic, I have my days too ...

3-4 Mai-Tai cocktails + some beers = surely you loose too much water. But they feel soooo gooood!
