For years, oil was the major determinant of which countries rose to -- and lost -- power in the global economy. Today, that commodity increasingly is water. This week on Benchmark, we hear about the water crisis in Cape Town, where authorities are warning they may need to turn off the taps, from local Bloomberg editor Robert Brand. Then, we take a journey through global water issues with Helen Mountford of the World Resources Institute. They speak with Scott Lanman of Bloomberg News and Daniel Moss of Bloomberg View.