This latter method was made possible by the extensive introduction of water metering, which was included in many concession contracts in the 1990s. The average household expenditure for water supply and sanitation in 2002 was 2.6%, ranging from 2.1% in the highest (wealthiest) quintile to 3.5% in the lowest (poorest) one.
This latter approach became feasible due to the widespread implementation of water metering, which was incorporated into numerous concession agreements in the 1990s. The average cost of water supply and sanitation for households in 2002 was 2.6%, varying from 2.1% among the wealthiest quintile to 3.5% among the poorest one.