According to the World Health Organization, the proportion of the world’s people who have access to what’s called “improved sanitation” has increased from around a quarter in 1980 to around two-thirds today. That’s a big step forward.5 Still, 2.5 billion people remain without improved sanitation, and improved sanitation itself is a low bar: the definition is that it “hygienically separates human excreta from human contact,” but it doesn’t necessarily treat the sewage itself. Fewer than half the world’s people have access to sanitation systems that do that.
