You can read about the drought on the Climate.gov post Day Zero approaches in Cape Town (Feb 7, 2018) by Michon Scott:
The exact date it will arrive depends on the latest calculations; as of February 6, 2018, Day Zero was projected to occur on May 11, 2018. That’s the day the taps might well be turned off for the roughly 4 million residents of South Africa’s second-largest city. Cape Town officials have blamed multiple factors in the water shortage, but one of the principal culprits is poor precipitation, and the problem has persisted since 2015.
The post includes interesting maps, such as the one here, and a link to Cape Town’s water dashboard. The U.S. is also looking at wide spread drought which you can learn more about at United States Drought Monitor.