The flush toilet is sanitary, convenient -- and needs lots of water. The problem is, that design only works if you have a functioning sewage system and access to a steady water supply. Those conditions often aren't met in the developing world.
The Bill and Melinda Gates Foundation recently hosted the "Reinvent the Toilet" fair, looking for alternatives to the type richer nations are familiar with. Contestants had to come up with systems that use a lot less water and crucially, can work in areas where power and sewage systems might not be an option. For developing nations toilets can be important -- millions are infected with water-borne diseases every year, such as cholera, and diarrhea can kill you if it dehydrates enough. In many countries the pit latrine is the standard, and the problem is they often leak into local water supplies.
First prize and $100,000 was awarded to the California Institute of Technology for their design: a tall blue contraption that is a self-contained, solar-powered toilet and wastewater treatment system.