Slum dwellers in Dar es Salaam pay the equivalent of £4 for 1,000 litres of water bought over time and by the canister. In the same Tanzanian city, wealthier households connected to the municipal supply pay just 17p. In the UK, the same volume of tap water costs 81p and in the US it is 34p. [i] The basic human need is for 20 litres of water per day for drinking, cooking and washing.

[i] Fiona Harvey, A costly thirst, Financial Times (April 2008)