What are the (a) reasons that the situation of empty reservoirs in the south of Johannesburg which began five years ago has not been addressed and (b) details of the water and/or reservoirs challenges faced by residents because the Meyershill and South Hills reservoirs were empty since in February 2022 and residents did not have a drop of water for nine days, and that there has been no water in the areas of Linmeyer, Risana, South Hills and Oakdene since 10 March 2022 as the reservoirs are also empty?