Here's an update [in french] on the right to water there:
Johannesburg court determines the right to water at 42 litters per person per day. Recently the Court confirmed the illegality of using prepaid meters set at 42 litters per day per person to provide free water to the very poor people.Bottom Line: 42 liters is 11 gallons (a typical shower). Can you use less per day? If not, then be thankful that you have more :)
It must be noticed that the same amount is also used in Flanders in Belgium since 1997 for the free allocation of water.
Following the court case, a more advanced system of rates will be set-up in July to avoid the criticisms of the court on automatic disconnection in case of arrears. The Johannesburg experience has the merit to seek to reconcile the right to water and the pricing requirements that must be protected to ensure the continuity of the service.