Water is absolutely essential to life1. In survival situations, there is something known as The Rule of Threes. It says that you can survive 3 minutes without air, 3 hours in inclement weather, 3 days without water, 3 weeks without food. We are going to assume that you don't have to worry about air to breathe or freezing to death as you begin your journey from hatchet in the woods to sending an email. That makes finding fresh water your highest priority. 
It's no wonder that the first great civilizations emerged alongside freshwater rivers such as the Nile, the Tigris, the Euphrates, the Indus and the Yangtze. These fresh water sources provided the large quantity of water needed for farming. You can clearly see the Nile from space at night. (Click on the image at right for a larger view)
Let's start with the basics. You need to know:
- Where fresh water comes from
- How you find it
- How to collect and store it
- How to treat it
- How much you are going to need for personal use or farming.
- Interesting facts about water (surprisingly important)
Interesting Facts about water:
Water not only dissolves more substances than sulfuric acid, it dissolves more substances than any other liquid. Because it is such a universal solvent, it is the basis of all biological processes in the human body. Its ability to dissolve substances is essential for transporting nutrients into cells, as well as, carrying waste products out of cells. Without water, there would be no life as we know it.1
In the year 2010, 884 million people world-wide still use unsafe drinking sources. (http://www.unicef.org/wash/)
The English word ‘rivals’ comes from the Latin word rīvalis , which literally means : one who shares the same brook. The notion being that neighbors compete for a precious resource.
Its chemical formula (H2O) is the best known formula in the world.
Unlike other liquids, water expands when it freezes. If it didn’t ponds would freeze from the bottom up. Ice is slippery partly because its solid form is less dense than its liquid form. When you step on ice you provide pressure that forces the ice to return to its more dense state of water. The resulting layer of liquid that forms between you and the ice is slippery. If you step on solid iron, the pressure just encourages the iron to stay solid.
It is the only natural substance found in all three states (solid, liquid, gas) at the temperatures normally found on Earth.
Water has a high specific heat. This means that it takes lots of heat to make it hot and once it is hot it holds heat well. One calorie of heat added to 1 gram of water will raise the temperature of the water by 1 degree C, in comparison to gold in which , One calorie of heat added to 1 gram of gold will raise the temperature of the gold by 33 degrees C.
A water molecule is bent resulting in a positively charged and a negatively charged end. These charged ends are what gives water its unique properties.
Foot Notes:
1Scientists believe that life isn’t possible without liquid water.Dr. Neil de Grasse Tyson, an astrophysicist and director of the Hayden Planetarium at the American Museum of Natural History says "Given that life on Earth is so dependent on water, and given that water is so prevalent in the universe, we don't feel that we're going out on a limb to say that life would require liquid water."