BBC News:Cape Town faces the unenviable situation of being the first major city in the modern era to run out of drinking water. However, the plight of the drought-hit South African city is just one extreme example of a problem that experts have long been warning about - water scarcity. One of the very important functions of the sun is to evaporate ocean water, desalinize it and move it over land where the fresh water falls as rain or snow. When weather patterns change shortages of water can develop. This has happened throughout history. The Romans took charge of water supply for their cities by building aqueducts. Today, nuclear power, solar or wind could be used to desalinate ocean water for water supply in arid countries. Nuclear powered ships could become mobile desalinization stations to meet temporary needs.
Business Insider: After three years of persistent drought, the government is warning that "Day Zero" — when they will be forced to turn off the faucets — will be April 16, 2018. That's when reservoirs and water sources will hit 13.5% capacity, at which point the city will move most residents to a strict bucket- and jug-based water rationing system.