Microsoft founder Bill Gates wants to build a better toilet. His foundation is hosting a “Reinvent The Toilet Fair” today, with cash prizes going to the most innovative designs. Why? Poop is a worldwide problem. Four out of every 10 people around the globe have no where to “go.” Poor sanitation leads to food and water tainted with fecal matter, which causes 2.5 billion cases of diarrhea in children under five and 1.5 million child deaths a year. The United Nation estimates that half of the world’s hospitalizations result from bad sanitation. Better sanitation could prevent most of those child deaths, provide safe drinking water and improve lives. Gates’ foundation has committed $370 million to the Water, Sanitation & Hygiene (WSH) initiative, which includes devising a 21st-century toilet.