'Coca-Cola, prices the poor can afford.' R8/l is not 'affordable' for syrup-flavored water (cf filtered water is R1/l), almost as costly as petrol. But it's a luxury item. 
Putting monopolies in charge of scarce, basic necessities is a bad idea. How did that work out w/ telecoms under privatised Telkom, Vodacom et al, banking, etc. De Lille (she of 'security upgrades'), former speech-writer ID cadre now 'water engineer' Limberg, CoCT and DA have badly mishandled the crisis, which she doesn't agree with. Since 2006 the population has increased 23% and dam capacity 20% (Berg River). City's had below-average rainfall since 2015 w/ little urgent intervention for alternatives and conservation until last/this year when it was too late. 
There's been a huge failure of planning and management by both city and government. But replacing their incompetence with the rent-seeking of South African private concerns, which generally cannot operate in a competitive environment, would be as bad.