In early 2018, Cape Town, South Africa came dangerously close to being the world’s first major city to run out of water. People lined up for blocks to collect spring water. Stores sold out of receptacles like buckets and bowls. Bottled water was rationed in tourist-heavy parts of the city. April 12 was designated “Day Zero”—the day the water was expected to dry up. City officials prepared for riots, keeping army and police ready to be deployed to water collection sources.