LONDON (Thomson Reuters Foundation) – Drought-stricken Cape Town could run out of water as soon as April, but South Africa is not alone in its struggle as ever more world cities battle acute water shortages. Water scarcity already affects more than 40 percent of the world’s population and is expected to rise due to global warming, with one in four people projected to face chronic or recurring shortages by 2050, according to the United Nations. Already hosting more than half the world’s people, cities are at the forefront of the problem, as population growth increases pressure on reserves, which are already stretched by too little rain and too much waste. Following are some of the crisis cities: SAO PAULO The reservoir supplying Sao Paulo, Brazil’s largest city and a metropolitan region of 20 million people, nearly dried up in 2015, as the country faced its worst drought in 80 years, depriving many residents of water for 12 hours a day. The city was criticized by U.N. experts for losing 31 percent of its treated water to leaks and theft, compared to an average of…