But thanks to its sophisticated water management efforts, the city may ride out the crisis.
However, other cities that lack these capacities are less likely to survive Day Zero.
Especially in developing countries, where urban water services are often provided by informal or illegal actors, running out of water could have dangerous ripple effects for peace and security.
But by 2050, most people in Asia and Africa will live in cities, where water supplies sometimes depend on violent entrepreneurs, criminal groups, and other informal or illegal service providers.
However, as their populations increase, the governments of some developing cities are falling behind, thus creating space for informal service providers, some of them armed, to fill.
Take, for example, military operations in Rio de Janeiro, Brazil: Every few years, the state attempts to clean house and reduce the level of violence.
Yet, as urban populations and water scarcity increases, these negotiated arrangements will be stressed to new heights.
Political players compete to secure territory, constituents, and bribes.
Karachi’s panoply of armed actors—including Taliban factions, Al Qaeda, and subversive groups—would only add to the political instability and risk of violent conflict.
For cities like Karachi, preventing Day Zero from becoming Day One of a violent conflict will require not only engineering solutions, but also political ones.