Water is the third most important substance for human survival.
After internet porn and beer?
Wait…you need water for beer.
Beer is mostly water. :-)
But based on the survival tips Rule of 3. You get thirty seconds if you’re bleeding, making blood number one. 3 minutes without air making it number two. 3 hours without shelter in a harsh environment no one thing counts as shelter and this is highly dependent on the environment. 3 days without water and depending on the environment that could shorten considerably making water the third most important substance.
I thought that “Quantum of Solace” was remarkably prescient in having the villains trying to control the water supply.