In Kenya, it cost 30KSH for a 500 mL bottle of cold Coke. 500 mL of water was 35KSH. So if you were thirsty, it was cheaper to down a bottle of Coke. With no reliable drinking water it is easy to see how people can turn to soda more often.
Here is how we became consumers of bottled water and some of its negative effects (other than the fact that you are paying for something which is essentially free).