According to Bill Gates, nearly 2.6 billion people, 40 percent of the world's population, do not have access to clean sanitation. This results in the deaths of approximately 1.5 million children under five every year.

The problem is that the modern toilet, whose design and technology has not changed much since its conception in 1775, requires a lot of water and energy, both of which are in short supply in much of the developing world.