Cape Town, South Africa, is at risk of going dry.The South Africa city is facing its worst drought in over a century, and reservoirs are predicted to dip below 13.5 percent by April 16 — a day authorities are ominously referring to as “day zero.”When those numbers are reached, Cape Town officials plan to shut off running water for most of the city’s four million residents. Citizens will then be forced to live off just 25 liters of water a day — roughly the equivalent of two toilet flushes.Cape Town authorities say that “day zero” can be avoided if citizens limit their water consumption to 50 liters a day. But protests have broken out, which blame the government for the drought.