Cape Town Counts Down to Day Zero

In early 2018, the City of Cape Town faced the imminent prospect of becoming the first major modern metropolis to deplete its municipal water supply. Following three consecutive years of exceptionally low winter rainfall beginning in 2015, the six major mountainous reservoirs supplying the Western Cape Water Supply System fell to critically low levels. By early 2018, Theewaterskloof Dam, built to hold about half of the city's water, was under 15 percent of capacity. Analysis by the Climate System Analysis Group at the University of Cape Town identified the multi-year drought as a rare event that would statistically occur roughly once every three centuries, and found that 2017 was the driest year in the dam catchments since at least 1933.

Municipal authorities responded by planning for an emergency scenario termed Day Zero. Defined as the moment usable dam levels dropped below 13.5 percent, Day Zero would trigger Level 7 restrictions. Under this protocol, ordinary taps across the city would be largely shut off, requiring roughly four million residents to collect an allocated ration of 25 litres per person per day from designated collection points. While essential infrastructure such as hospitals, the central business district, and informal settlements would remain connected, projections in January 2018 warned that Day Zero could arrive as early as mid-April, threatening widespread economic disruption and raising fears over hygiene and public health.