Water molecules have many different characteristics which make water so unique and important. These include polarity, surface tension/cohesion and adhesion. All these features about water are not just important for itself but also for human existence on planet Earth
This is an example of water using surface tension of water on a leaf
Polar molecules(which water is) are molecules that can dissolve other molecules. This means that water could dissolve unwanted substances in your body which could harm and damage your organs and other important parts of the body which makes water be very important in our body.
http://www.wisegeek.org/how-effective-is-salt-water-as-a-mouthwash.htm This is an example of table salt in water, when you stir the salt in the water, the salt will dissolve in it because the salt is also a polar molecule and water also dissolved the salt which makes both molecules polar.
Surface Tension is where two things can be attached together by the attraction of their particles in the liquid. This goes with cohesion which is where something is able to stick together with alike molecules like water molecules sticking to other water molecules. Surface Tension also goes with adhesion which is where something is able to stick together with unlike molecules like water sticking to a ceiling. So Surface Tension is cohesion and adhesion as one. Without Cohesion, planet Earth would have no oceans or any other large bodies of water because water molecules couldn't join with other water molecules to make huge areas of water.
This is an example of surface tension where the water is attracted to the ceiling and is attached.
This is another example of surface tension where water going down something still as water droplets