In the industrialized nations, we tend to assume that basic services, such as heating, lighting and drinkable water will always be available to us. In other parts of the world, the most of important and problematic need of all is often potable water; it's either locally very scarce, or if it is available, it's not safe to drink.
We have some technologies that are actually in the field now, and others that are being developed to try to bring science to bear on this most basic problem - namely providing clean drinking water as needed, at a manageable cost.
The main areas for these efforts are:
1 - producing drinking water from abundant sea water
2 - producing drinking water in arid areas
3 - producing drinking water from available, but contaminated water
Engadget describes six technologies to address these.