India has the largest number of open defecators in the world, over 600 million of them. At a certain level, this fact is inescapable. Within a hundred yards of our five star hotel in New Delhi, we could find expanses of human feces—we could find them because we could smell them. Touring Delhi slum clusters with local activists, we traversed neighborhoods where 5,000 people share 20 public toilets, which is nearly the same as having no toilets, resulting in even vaster expanses of human feces. But in urban areas, open defecation can also be invisible in the way poor people can quickly become invisible.