The international community is marking World Water Day this year under the theme of water and urbanization - noting that for the first time in history, more than one-half of the world’s population now lives in cities. In Africa, which has the highest urbanization rate in the world, 70 percent of city dwellers live in slums or shantytowns, often called informal settlements.   VOA's Scott Bobb recently visited the Makause community outside Johannesburg and has this report.